Mixed metal oxide coatings applied using spatial atomic layer deposition and uses thereof

Abstract

Systems and methods for manufacturing and use of an electrode are provided. The coated electrode includes an electrically conductive substrate, a first coating, and a second coating. The first coating may be one or more of platinum, iridium, titanium, and tantalum, and the second coating may be one or more of tantalum, iridium, platinum, or ruthenium. The second coating has a substantially uniform composition and a thickness of less than about 100 nm. Methods of preparing the electrode are disclosed. The electrode may be used in, for example, an electrolytic cell, that is part of a system such as an electrolyzer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No. 63 / 450,990, filed on Mar. 9, 2023, titled “Mixed Metal Oxide Coatings Applied Using Spatial Atomic Layer Deposition,” U.S. Provisional Patent Application Ser. No. 63 / 452,509, filed on Mar. 16, 2023, titled “Platinum Coatings Applied Using Spatial Atomic Layer Deposition,” and U.S. Provisional Patent Application Ser. No. 63 / 608,336, filed on Dec. 11, 2023, titled “Metallic Interlayers for Catalytic Porous Transport Layers in Polymer Electrolyte Membrane Water Electrolysis,” the entire disclosures of each are hereby incorporated by reference in their entirety for all purposes.FIELD OF THE DISCLOSURE

[0002] Aspects relate generally to electrode coatings and, more particularly, to multi-layered electrode coatings, their method of preparation, and use.SUMMARY

[0003] In accordance with an aspect, there is provided an electrode. The electrode may include an electrically conductive substrate. The electrode may include a first coating on a surface of the electrically conductive substrate. The first coating on the surface of the electrically conductive substrate may include one or more of platinum, iridium, titanium, and tantalum. The electrode further may include a second coating a surface of the first coating. The second coating on the surface of the first coating may include one or more of tantalum, iridium, platinum, or ruthenium. The second coating may have a substantially uniform composition and a thickness of less than about 100 nm.

[0004] In some embodiments, the electrically conductive substrate may be a metal. The metal may be selected from the group consisting of titanium, zirconium, niobium, and tantalum, or alloys thereof. In specific embodiments, the metal may be titanium or a titanium alloy.

[0005] In some embodiments, the first coating may include a mixture of titanium and tantalum or any oxide thereof, e.g., a mixture of a titanium oxide and a tantalum oxide. In some embodiments, the first coating may include an iridium-based mixed metal oxide. In particular embodiments, the first coating may include platinum or an oxide thereof.

[0006] In some embodiments, the first coating may include about 0.1 g / m2 to about 100 g / m2 tantalum. In some embodiments, the first coating may include about 0.1 g / m2 to about 100 g / m2 titanium. In some embodiments, the first coating may include about 0.1 g / m2 to about 100 g / m2 iridium. In some embodiments, the first coating may include about 0.1 g / m2 to about 100 g / m2 platinum.

[0007] In some embodiments, the first coating has a thickness of about 100 nm to about 3000 nm.

[0008] In certain embodiments, e.g., where the first coating may include a mixture of titanium and tantalum or oxides thereof, the second coating may include a mixture of iridium and tantalum or any oxide thereof, e.g., a mixture of an iridium oxide and a tantalum oxide. A molar ratio of iridium to tantalum in the second coating may be about 2:1 to about 9:1. In some embodiments, the second coating may include about 0.1 g / m2 to about 100 g / m2 tantalum and about 0.1 g / m2 to about 100 g / m2 iridium.

[0009] In some embodiments, e.g., where the first coating may include an iridium-based mixed metal oxide or platinum or an oxide thereof, the second coating may include iridium or an oxide thereof. In some embodiments, the second coating may include about 0.1 g / m2 to about 100 g / m2 iridium.

[0010] In some embodiments, e.g., where the first coating may include an iridium-based mixed metal oxide or platinum or an oxide thereof, the second coating may include platinum or an oxide thereof. In some embodiments, the second coating may include about 0.1 g / m2 to about 200 g / m2 platinum.

[0011] In some embodiments, the second coating may have a thickness of about 10 nm to about 100 nm.

[0012] In any embodiment of an electrode of this disclosure, the electrode may provide for about a 300% improvement in durability than an electrode comprising a single layer coating consisting of a composition of the second coating.

[0013] In any embodiment of an electrode of this disclosure, the electrode may provide for about a 50% greater activity than an electrode comprising a single layer coating consisting of a composition of the second coating.

[0014] In accordance with an aspect, there is provided a method of preparing an electrode. The method may include applying a first coating including one or more of platinum, iridium, titanium, or tantalum to a surface of an electrically conductive substrate. The method may include applying a second coating comprising an oxide of one or more of tantalum, iridium, platinum, or ruthenium to a surface of the first coating. The applied second coating may have a substantially uniform composition and a thickness of less than about 100 nm.

[0015] In further embodiments, the method may include, prior to applying the first coating, preparing the electrically conductive substrate to remove contaminants and to develop the surface.

[0016] In some embodiments, the electrically conductive substrate may be prepared using one or more of a chemical bath, laser treatment, oxidative plasma treatment, or reductive plasma treatment.

[0017] In some embodiments, the first coating may be applied using physical application, chemical application, or magnetron sputtering.

[0018] In further embodiments, the method may include, after applying the first coating, drying the first coating.

[0019] In some embodiments, the second coating may be applied using atomic layer deposition, e.g., spatial atomic layer deposition (sALD).

[0020] In further embodiments, the method may include, after applying the second coating, heat treating the electrode.

[0021] In accordance with an aspect, there is provided a method of manufacturing an electrolytic cell. The method may include preparing an electrode. The prepared electrode may be any electrode disclosed herein, e.g., an electrode including an electrically conductive substrate, a first coating on a surface of the electrically conductive substrate including one or more of platinum, iridium, titanium, and tantalum and a second coating on a surface of the first coating including one or more of tantalum, iridium, platinum, or ruthenium having a substantially uniform composition and a thickness of less than about 100 nm. The method further may include installing the electrode in an electrolytic cell.

[0022] In accordance with an aspect, there is provided an electrolytic cell. The electrolytic cell may have an anode and a cathode. The electrolytic cell may include an electrolyte layer disposed between the anode and cathode permitting transport of protons from the anode to the cathode. The electrolyte layer may include a substrate sufficient for transporting protons, a first coating on a surface of the substrate including one or more of platinum, iridium, titanium, and tantalum, and a second coating on a surface of first coating including one or more of tantalum, iridium, platinum, or ruthenium. The second coating may have a substantially uniform composition and a thickness of less than about 100 nm.

[0023] In accordance with an aspect, there is provided an electrolytic cell. The electrolytic cell may have an anode that may be any electrode disclosed herein, e.g., an electrode including an electrically conductive substrate, a first coating on a surface of the electrically conductive substrate including one or more of platinum, iridium, titanium, and tantalum and a second coating on a surface of the first coating including one or more of tantalum, iridium, platinum, or ruthenium having a substantially uniform composition and a thickness of less than about 100 nm. The electrolytic cell may include a cathode. The electrolytic cell further may include an electrolyte layer disposed between the anode and cathode, the electrolyte layer permitting transport of protons from the anode to the cathode.

[0024] In accordance with an aspect, there is provided an electrolyzer. The electrolyzer may include an electrolytic cell as disclosed herein, e.g., an electrolytic cell having an anode that may be any electrode disclosed herein, e.g., an electrode including an electrically conductive substrate, a first coating on a surface of the electrically conductive substrate including one or more of platinum, iridium, titanium, and tantalum and a second coating a surface of the first coating including one or more of tantalum, iridium, platinum, or ruthenium having a substantially uniform composition and a thickness of less than about 100 nm, a cathode, and an electrolyte layer disposed between the anode and cathode permitting transport of protons from the anode to the cathode. The electrolyzer may include an electrolytic cell as disclosed herein, e.g., an electrolytic cell having an anode, a cathode, and an electrolytic cell including an electrolyte layer disposed between the anode and cathode permitting transport of protons from the anode to the cathode including a substrate sufficient for transporting protons, a first coating on a surface of the substrate including one or more of platinum, iridium, titanium, and tantalum, and a second coating on a surface of first coating including one or more of tantalum, iridium, platinum, or ruthenium having a substantially uniform composition and a thickness of less than about 100 nm.

[0025] The electrolyzer further may include a power source for driving the electrolytic cell.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various aspects of at least one embodiment are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide illustration and a further understanding of the various aspects and embodiments and are incorporated in and constitute a part of this specification but are not intended as a definition of the limits of the disclosure. Where technical features in the figures, detailed description, or any claim are followed by reference signs, the reference signs have been included for the sole purpose of increasing the intelligibility of the figures and description. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure. In the figures:

[0027] FIG. 1 is a side view of an electrode according to one embodiment of the disclosure;

[0028] FIG. 2 is a schematic of an electrolyzer according to one embodiment of the disclosure;

[0029] FIG. 3 illustrates the lifetime of electrode samples prepared with different surface treatments and deposition methods;

[0030] FIG. 4 illustrates the lifetime of electrode samples prepared with deposition methods;

[0031] FIG. 5A illustrates a scanning electron microscopy (SEM) image of a vertical cross-section of an electrode having an electrodeposited second layer;

[0032] FIG. 5B illustrates a scanning electron microscopy (SEM) image of a vertical cross-section of an electrode having a second layer deposited with sALD;

[0033] FIG. 6 illustrates the oxygen evolution reaction (OER) activity of electrodes with and without a Ti—Ta interlayer;

[0034] FIG. 7 illustrates the durability of electrodes with and without a Ti—Ta interlayer;

[0035] FIG. 8 illustrates the performance over time of electrodes with and without a Ti—Ta interlayer when used in a polymer electrolyte membrane (PEM) electrolyzer;

[0036] FIG. 9 illustrates a focused ion beam vertical cross-section of an electrode according to this disclosure as an electron map;

[0037] FIG. 10A-10C illustrates SEM / energy dispersive X-ray spectroscopy (EDS) map images of the distribution of various elements in the electrode; and

[0038] FIG. 11 illustrates the relative distribution of Ir and Ta in the electrode illustrated in FIGS. 9 and 10A-1C taken along the solid line illustrated in FIG. 9.DETAILED DESCRIPTION

[0039] An electrode is a solid electric conductor through which an electric current enters or leaves an electrolytic cell or other medium. Electrodes may be used in any electrochemical process that requires an electrical conductor. For example, electrodes may be used in electro-galvanizing, electroplating, electro-tinning, electroforming, electrowinning (e.g., electrowinning of metals such as copper, nickel, and zinc), and other electrochemical processes. Electrodes may be used in any halogen-evolving processes, such as hypochlorite, chlorate, and chlor alkali production, or in chlor-organic synthesis. Electrodes may also be used in electrolytic chlorination systems and processes. Electrolytic chlorination systems and processes may produce sodium hypochlorite through the electrolysis of a brine solution.

[0040] Electrodes may be used in electrolytic cells. An electrolytic cell is an electrochemical cell that may be used to overcome a positive free energy, which indicates a non-spontaneous reaction, and force a chemical reaction in a desired direction. The electrolytic cell converts electrical energy into chemical energy or produces chemical products through a chemical reaction.

[0041] The electrode in an electrolytic cell may be referred to as either an anode or a cathode, depending on the direction of electrical current through the cell. The anode is an electrode at which electrons leave the cell and oxidation of ions within the cell occurs, and the cathode is an electrode at which electrons enter the cell and reduction of ions within the cell occurs. Under these conditions, the direction of current through the cell is from the anode to the cathode. Each electrode may become either the anode or the cathode depending on the process and the direction of current through the cell.

[0042] The design of electrolytic cells and their electrodes may depend on one or more factors. The one or more factors may include, for example, construction and operating costs, desired product, electrical, chemical, and transport properties, electrode materials, shapes and surface properties, pH of the system (for example, electrolyte pH), and temperature of the system (for example, electrolyte temperature), competing undesirable reactions, and undesirable byproducts.

[0043] Depending on the electrochemical process, one or more properties of the process, for example, one or more of current density in the electrolytic cell, pH of the system (for example, electrolyte pH), or temperature of the system (for example, electrolyte temperature) may affect the effectiveness of the system and process, for example, the service life of the electrodes. For example, exposure to one or more of a high current density, low pH, or high temperature may lower the service life of an electrode. In some embodiments, exposure to one or more of a high current density, low pH, or high temperature may cause passivation of the electrode.

[0044] Passivation is the inhibition of a dissolution reaction caused by the formation of non-dissolving films. A dissolution reaction is a process by which the original state of a solvent becomes a solute. Anode and / or cathode passivation may result in one or more of lost production capacity, increased power costs, and decreased anode and / or cathode quality. When titanium is used as a substrate, anode passivation is the growth of an insulating titanium dioxide layer in the coating and the substrate, which increases the electrical potential in the anode, and causes deactivation of the anode. In some embodiments, exposure to one or more of a high current density, low pH, or high temperature may cause wear of the electrode. Wear of the electrode, or “electrode wear” is the removal of material from the electrode. In some embodiments, exposure to one or more of a high current density, low pH, or high temperature may cause both passivation and wear of the electrode.

[0045] As noted above, the electrolytic cell may comprise an electrolyte. An electrolyte is a substance that produces an electrically conducting solution when in contact with a polar solvent, such as water. Electrolytes can be solid or liquid. When an electric potential, or voltage, is applied to the electrolyte, the cations are drawn to the electrode that has an abundance of electrons, and the anions are drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. An electrolyte may be referred to as strong or weak, depending on the dissociation of the solute. If a high proportion, for example, greater than 50%, of the solute dissociates to form free ions, the electrolyte is strong. If a high proportion, for example, less than 50%, of the solute does not dissociate, the electrolyte is weak.

[0046] In some embodiments, electrodes may be exposed to electrolytes having a low pH. Electrolytes having a low pH may refer to electrolytes having an acidic pH, for example, less than a pH of 7. For example, the electrolytes may be strong acid electrolytes. In some aspects, the strong acid electrolyte may be sulfuric acid.

[0047] In some embodiments, low pH may refer to electrolytes having a pH lower than about 3. In some embodiments, low pH may refer to electrolytes having a pH lower than about 2. In some embodiments, low pH may refer to electrolytes having a pH lower than about 1. In some embodiments, low pH may refer to a pH lower than about 0.8. In some embodiments, low pH may refer to a pH lower than about 0.6. In some embodiments, low pH may refer to a pH lower than about 0.4. In some embodiments, low pH may refer to a pH lower than about 0.2.

[0048] In some embodiments, electrodes may be exposed to electrolytes having a high temperature. A high temperature may be a temperature at which the cell voltage of the electrode undesirably decreases. A high temperature may be a temperature higher than about 50° C. In some embodiments, a high temperature is higher than about 55° C. In some embodiments, a high temperature is higher than about 60° C. In some embodiments, a high temperature is higher than about 65° C. In some embodiments, a high temperature is higher than about 70° C.

[0049] In some embodiments, electrodes may be exposed to high current densities. A current density is a measure of the density of an electric current. It is defined as a vector whose magnitude is the electric current per cross-sectional area, and may be measured in, for example, amperes per square meter (A / m2). High current densities may have undesirable consequences. For example, high current densities may have undesirable consequences to one or more of a coating, electrode, electrolytic cell, and electrochemical device. Electrodes have a finite, positive resistance, causing them to dissipate power in the form of heat. The current density must be kept sufficiently low to protect the electrode from passivation or wear.

[0050] In some embodiments, a high current density is a current density that causes at least one of passivation and wear of the electrodes. In some embodiments, a high current density may be higher than about 0.5 kA / m2. For example, a high current density may be higher than about 1.0 kA / m2. A high current density may be higher than about 1.5 kA / m2. In some embodiments, a high current density may be higher than about 2.0 kA / m2. For example, a high current density may be higher than about 2.5 kA / m2. In some embodiments, a high current density may be higher than about 3.0 kA / m2. For example, a high current density may be higher than about 3.5 kA / m2. In some embodiments, a high current density may be higher than about 4.0 kA / m2. For example, a high current density may be higher than about 4.5 kA / m2. In some embodiments, a high current density may be about 5.0 kA / m2. In some embodiments, a high current density may be up to about 15 kA / m2.

[0051] One application making use of electrodes of this disclosure is water electrolysis for the at-scale production of hydrogen gas and oxygen gas. Polymer electrolyte membrane (PEM) water electrolysis is a technology that uses an electrochemical process to split water into its constituent elements, hydrogen and oxygen. The process involves the use of a polymer electrolyte membrane (PEM) as the electrolyte material, which allows for the selective transport of protons while blocking the passage of electrons. PEM water electrolysis utilizes an electrolysis cell, which typically comprises two electrodes, an anode and cathode, immersed in water. The electrodes are often made of porous, conductive materials. The PEM is a solid polymer material that acts as an electrolyte, allowing for the transport of protons from the anode to the cathode while preventing the mixing of hydrogen and oxygen gases. Hydrogen gas is generated at the cathode, and oxygen gas is produced at the anode. The protons transported through the PEM combine with electrons at the cathode to form hydrogen gas. The electrolyte membrane of PEM electrolyzers is generally coated in a catalytic material. In this configuration, the catalyst coated membrane (CCM) is disposed between two porous transport layers, typically made from titanium, carbon, or another porous conductive material. To make electrical contact, the porous transport layers are forced into physical contact with the CCM. One of the advantages of PEM water electrolysis is its ability to produce high-purity hydrogen gas, as the membrane selectively allows only protons to pass through, preventing gas crossover and contamination. For this reason, PEM water electrolysis is commonly used in the production of hydrogen for various applications, including fuel cells for vehicles, energy storage, and industrial processes.

[0052] Similarly, a catalyst-coated porous transport layer (PTL) is a component commonly used in various electrochemical devices, including electrolyzers, combining a porous material with a catalyst to enhance the efficiency of chemical reactions occurring at the electrode interface. The porous transport layer is typically a thin, permeable material that facilitates the movement of reactants and products between the electrode and the surrounding environment, providing a pathway for gases and ions to reach the catalyst layer while maintaining good electrical conductivity. The catalyst coating is a thin layer of catalytic material applied onto the porous transport layer, which aids in accelerating specific electrochemical reactions that take place at the electrode surface. The catalyst-coated porous transport layer increases the effective surface area for electrochemical reactions, which helps to maximize the contact between reactants and the catalyst, improving reaction kinetics. The porous structure of the transport layer allows for the efficient transport of reactants (e.g., hydrogen, oxygen) and products (e.g., water) to and from the catalyst sites. The porous transport layer also serves as an electron conductor, facilitating the flow of electrons generated during electrochemical reactions. Furthermore, the porosity of the transport layer allows for the diffusion of gases to and from the catalyst sites.

[0053] Mixed metal oxide coatings for dimensionally stable anodes are typically prepared through a paint-thermal decomposition route. In this preparation method, the precious metal precursor, typically a chloride salt precursor, and a metal precursor, e.g., Ti, Zr, Nb, or Ta, are dissolved in a solvent, e.g., an alcohol, and applied onto a metallic or other conductive substrate. After the solvent has evaporated, the coated substate is heat-treated in an oven or furnace to convert the precursors into their respective oxides. A non-limiting example of an electrode made using the aforementioned process is a mixture of iridium chloride and tantalum ethoxide, dissolved in butanol, and applied onto a Ti substrate. After heat treating the coated substrate at 400-500° C., a mixture of iridium oxide and tantalum oxide is formed, which forms the active electrocatalyst.

[0054] Spatial Atomic Layer Deposition (sALD) is a derivative of standard (or time-separated) Atomic Layer Deposition (ALD) and represents a cutting-edge technique in thin film deposition, offering precise control over thickness and uniformity at the nanoscale. In sALD, metal precursors are used that are very volatile and decompose at low temperatures. The precursors are transferred via a carrier gas onto a titanium substrate, either sequentially (“supercycles”) or simultaneously (“co-dosing”). In a next step that is spatially separated from the previous step in sALD, the precursors are converted in their respective oxides. Compared to conventional ALD techniques, sALD segregates surface reactions into distinct zones rather than conducting them sequentially within a single reaction chamber. Film growth is achieved by exposing the substrate to the locations containing the different precursors. This approach enables deposition on larger surfaces and non-planar substrates while upholding advantages of traditional ALD. Eliminating the purge step that is necessary in conventional ALD, accelerates the process, making it well-suited for high-throughput methods and significantly enhances its adaptability and scalability at reduced expenses. Furthermore, one benefit of sALD is that it can operate at ambient pressures while still maintaining consistent deposition rates and has no requirement for vacuum chambers, permitting the processing to be automated.

[0055] An electrode may include an electrically conductive substrate to be coated with one or more layers of coatings. A coating may refer to one application or more than one application of a coating, i.e., a first layer, a second layer, and so on. Through use of an electrode having multiple coatings, a synergistic effect may result. The synergistic effect may provide optimal, e.g., increased, performance of the electrode, as compared to the sum of the performance of an electrode having a first coating and the performance of an electrode having a second coating.

[0056] As used herein, a “two coating electrode” refers to an electrode that is coated on at least one of its surfaces with a first coating comprising a mixture to provide the first coating, and a second coating that at least partially coats the first coating to provide a second coating. More than one application of the first coating may be performed to achieve the desired coating loading. More than one application of the second coating may be performed to achieve the desired coating mass loading. In general, the mass loadings of the coatings are based on the geometric areas the materials are being applied to, i.e., not limited to specifical surface areas of the electrode.

[0057] The first coating may be applied directly to a surface of the electrode substrate as an interlayer, and the second coating may be applied directly to a surface of the first coating. For either the first coating or the second coating, the application of the coating can be fractional on the surface or can be over substantially all of the exposed surface. The first coating and the second coating may increase activity of the electrode. In some embodiments, the first coating may reduce corrosion of the electrode. In some embodiments, the second coating may reduce wear of the electrode. In some embodiments, the second coating may increase catalytic activity of the electrode. In some embodiments, the electrode substrate surface may be at least partially covered with a first coating comprising a mixture. The first coating may be a mixture comprising titanium and tantalum or an oxide thereof, e.g., a mixture of a titanium oxide and a tantalum oxide. In some embodiments, the first coating may be a mixture consisting of titanium and tantalum or an oxide thereof, e.g., a mixture of a titanium oxide and a tantalum oxide. In some embodiments, the first coating may be substantially platinum or an oxide thereof. The first coating may be a mixture comprising platinum and iridium or an oxide thereof, e.g., a mixture of a platinum oxide and an iridium oxide. For platinum coatings, a first coating of platinum may not require a second coating of any other material, e.g., additional platinum. Platinum deposited using methods disclosed herein, e.g., sALD and the like, provides for a robust catalytic surface without additional coatings or other treatments. In some embodiments, when platinum is used as a first coating, e.g., an interlayer, deposited using methods disclosed herein, e.g., sALD, additional platinum may be deposited using other deposition methods, such as electrodeposition and related methods. In some embodiments, the first coating may be a mixture consisting essentially of iridium or an iridium-based mixed metal oxide (MMO).

[0058] The first coating may be at least partially covered by a second coating comprising a mixture. In some embodiments, the second coating may be a mixture comprising iridium and tantalum or an oxide thereof, e.g., a mixture of an iridium oxide and a tantalum oxide. In some embodiments, the second coating may be a mixture consisting essentially of iridium and tantalum or an oxide thereof, e.g., a mixture of an iridium oxide and a tantalum oxide. In some embodiments, the first coating may be a mixture consisting essentially of iridium or an iridium-based mixed metal oxide (MMO). In some embodiments, the second coating may be substantially platinum or an oxide thereof. In specific embodiments, the second coating includes iridium.

[0059] The electrode substrate may be any substrate having electrically conductive properties. The electrode substrate may be any substrate having sufficient mechanical strength to serve as a support for the coating. The electrode substrate may be any substrate having a resistance to corrosion when exposed to the interior environment of an electrolytic cell. The electrode substrate may be a metal. In some embodiments, the electrode substrate may be a valve metal or an alloy thereof. Valve metals are any of the transition metals of Group IV and V of the periodic table, including titanium, vanadium, zirconium, niobium, hafnium, and tantalum. In some embodiments, suitable valve metals include titanium, zirconium, niobium, and tantalum. In some embodiments, the electrode substrate preferably comprises titanium. Titanium may be preferred because of its availability, chemical properties, and low cost.

[0060] The first coating may comprise a mixture of titanium and tantalum or an oxide thereof, e.g., a mixture of a titanium oxide and a tantalum oxide. In some embodiments, the first coating may consist essentially of titanium and tantalum or an oxide thereof, e.g., a mixture of a titanium oxide and a tantalum oxide. In some embodiments, the first coating may consist of a mixture of titanium and tantalum or an oxide thereof, e.g., a mixture of a titanium oxide and a tantalum oxide. In this configuration, the first coating may include about 0.1 g / m2 to about 100 g / m2 tantalum. For example, the first coating may include about 0.1 g / m2 to about 100 g / m2 tantalum, e.g., about 1 g / m2 to about 10 g / m2 tantalum, about 5 g / m2 to about 15 g / m2 tantalum, about 10 g / m2 to about 20 g / m2 tantalum, about 15 g / m2 to about 25 g / m2 tantalum, about 20 g / m2 to about 30 g / m2 tantalum, about 25 g / m2 to about 35 g / m2 tantalum, about 30 g / m2 to about 40 g / m2 tantalum, about 35 g / m2 to about 45 g / m2 tantalum, about 40 g / m2 to about 50 g / m2 tantalum, about 45 g / m2 to about 55 g / m2 tantalum, about 50 g / m2 to about 60 g / m2 tantalum, about 55 g / m2 to about 65 g / m2 tantalum, about 60 g / m2 to about 70 g / m2 tantalum, about 65 g / m2 to about 75 g / m2 tantalum, about 70 g / m2 to about 80 g / m2 tantalum, about 75 g / m2 to about 85 g / m2 tantalum, about 80 g / m2 to about 90 g / m2 tantalum, about 85 g / m2 to about 95 g / m2 tantalum, or about 90 g / m2 to about 100 g / m2 tantalum.

[0061] In some embodiments, the first coating may include about 0.1 g / m2 of tantalum, about 0.2 g / m2 of tantalum, about 0.3 g / m2 of tantalum, about 0.4 g / m2 of tantalum, about 0.5 g / m2 of tantalum, about 0.6 g / m2 of tantalum, about 0.7 g / m2 of tantalum, about 0.8 g / m2 of tantalum, about 0.9 g / m2 of tantalum, about 1 g / m2 of tantalum, about 2 g / m2 of tantalum, about 3 g / m2 of tantalum, about 4 g / m2 of tantalum, about 5 g / m2 of tantalum, about 6 g / m2 of tantalum, about 7 g / m2 of tantalum, about 8 g / m2 of tantalum, about 9 g / m2 of tantalum, about 10 g / m2 of tantalum, about 11 g / m2 of tantalum, about 12 g / m2 of tantalum, about 13 g / m2 of tantalum, about 14 g / m2 of tantalum, about 15 g / m2 of tantalum, about 16 g / m2 of tantalum, about 17 g / m2 of tantalum, about 18 g / m2 of tantalum, about 19 g / m2 of tantalum, about 20 g / m2 of tantalum, about 21 g / m2 of tantalum, about 22 g / m2 of tantalum, about 23 g / m2 of tantalum, about 24 g / m2 of tantalum, about 25 g / m2 of tantalum, about 26 g / m2 of tantalum, about 27 g / m2 of tantalum, about 28 g / m2 of tantalum, about 29 g / m2 of tantalum, about 30 g / m2 of tantalum, about 31 g / m2 of tantalum, about 32 g / m2 of tantalum, about 33 g / m2 of tantalum, about 34 g / m2 of tantalum, about 35 g / m2 of tantalum, about 36 g / m2 of tantalum, about 37 g / m2 of tantalum, about 38 g / m2 of tantalum, about 39 g / m2 of tantalum, about 40 g / m2 of tantalum, about 41 g / m2 of tantalum, about 42 g / m2 of tantalum, about 43 g / m2 of tantalum, about 44 g / m2 of tantalum, about 45 g / m2 of tantalum, about 46 g / m2 of tantalum, about 47 g / m2 of tantalum, about 48 g / m2 of tantalum, about 49 g / m2 of tantalum, about 50 g / m2 of tantalum, about 51 g / m2 of tantalum, about 52 g / m2 of tantalum, about 53 g / m2 of tantalum, about 54 g / m2 of tantalum, about 55 g / m2 of tantalum, about 56 g / m2 of tantalum, about 57 g / m2 of tantalum, about 58 g / m2 of tantalum, about 59 g / m2 of tantalum, about 60 g / m2 of tantalum, about 61 g / m2 of tantalum, about 62 g / m2 of tantalum, about 63 g / m2 of tantalum, about 64 g / m2 of tantalum, about 65 g / m2 of tantalum, about 66 g / m2 of tantalum, about 67 g / m2 of tantalum, about 68 g / m2 of tantalum, about 69 g / m2 of tantalum, about 70 g / m2 of tantalum, about 71 g / m2 of tantalum, about 72 g / m2 of tantalum, about 73 g / m2 of tantalum, about 74 g / m2 of tantalum, about 75 g / m2 of tantalum, about 76 g / m2 of tantalum, about 77 g / m2 of tantalum, about 78 g / m2 of tantalum, about 79 g / m2 of tantalum, about 80 g / m2 of tantalum, about 81 g / m2 of tantalum, about 82 g / m2 of tantalum, about 83 g / m2 of tantalum, about 84 g / m2 of tantalum, about 85 g / m2 of tantalum, about 86 g / m2 of tantalum, about 87 g / m2 of tantalum, about 88 g / m2 of tantalum, about 89 g / m2 of tantalum, about 20 g / m2 of tantalum, about 91 g / m2 of tantalum, about 92 g / m2 of tantalum, about 93 g / m2 of tantalum, about 94 g / m2 of tantalum, about 95 g / m2 of tantalum, about 96 g / m2 of tantalum, about 97 g / m2 of tantalum, about 98 g / m2 of tantalum, about 99 g / m2 of tantalum, or about 100 g / m2 of tantalum.

[0062] The first coating may include about 0.1 g / m2 to about 100 g / m2 titanium, e.g., about 1 g / m2 to about 10 g / m2 titanium, about 5 g / m2 to about 15 g / m2 titanium, about 10 g / m2 to about 20 g / m2 titanium, about 15 g / m2 to about 25 g / m2 titanium, about 20 g / m2 to about 30 g / m2 titanium, about 25 g / m2 to about 35 g / m2 titanium, about 30 g / m2 to about 40 g / m2 titanium, about 35 g / m2 to about 45 g / m2 titanium, about 40 g / m2 to about 50 g / m2 titanium, about 45 g / m2 to about 55 g / m2 titanium, about 50 g / m2 to about 60 g / m2 titanium, about 55 g / m2 to about 65 g / m2 titanium, about 60 g / m2 to about 70 g / m2 titanium, about 65 g / m2 to about 75 g / m2 titanium, about 70 g / m2 to about 80 g / m2 titanium, about 75 g / m2 to about 85 g / m2 titanium, about 80 g / m2 to about 90 g / m2 titanium, about 85 g / m2 to about 95 g / m2 titanium, or about 90 g / m2 to about 100 g / m2 titanium.

[0063] In some embodiments, the first coating may include about 0.1 g / m2 of titanium, about 0.2 g / m2 of titanium, about 0.3 g / m2 of titanium, about 0.4 g / m2 of titanium, about 0.5 g / m2 of titanium, about 0.6 g / m2 of titanium, about 0.7 g / m2 of titanium, about 0.8 g / m2 of titanium, about 0.9 g / m2 of titanium, about 1 g / m2 of titanium, about 2 g / m2 of titanium, about 3 g / m2 of titanium, about 4 g / m2 of titanium, about 5 g / m2 of titanium, about 6 g / m2 of titanium, about 7 g / m2 of titanium, about 8 g / m2 of titanium, about 9 g / m2 of titanium, about 10 g / m2 of titanium, about 11 g / m2 of titanium, about 12 g / m2 of titanium, about 13 g / m2 of titanium, about 14 g / m2 of titanium, about 15 g / m2 of titanium, about 16 g / m2 of titanium, about 17 g / m2 of titanium, about 18 g / m2 of titanium, about 19 g / m2 of titanium, about 20 g / m2 of titanium, about 21 g / m2 of titanium, about 22 g / m2 of titanium, about 23 g / m2 of titanium, about 24 g / m2 of titanium, about 25 g / m2 of titanium, about 26 g / m2 of titanium, about 27 g / m2 of titanium, about 28 g / m2 of titanium, about 29 g / m2 of titanium, about 30 g / m2 of titanium, about 31 g / m2 of titanium, about 32 g / m2 of titanium, about 33 g / m2 of titanium, about 34 g / m2 of titanium, about 35 g / m2 of titanium, about 36 g / m2 of titanium, about 37 g / m2 of titanium, about 38 g / m2 of titanium, about 39 g / m2 of titanium, about 40 g / m2 of titanium, about 41 g / m2 of titanium, about 42 g / m2 of titanium, about 43 g / m2 of titanium, about 44 g / m2 of titanium, about 45 g / m2 of titanium, about 46 g / m2 of titanium, about 47 g / m2 of titanium, about 48 g / m2 of titanium, about 49 g / m2 of titanium, about 50 g / m2 of titanium, about 51 g / m2 of titanium, about 52 g / m2 of titanium, about 53 g / m2 of titanium, about 54 g / m2 of titanium, about 55 g / m2 of titanium, about 56 g / m2 of titanium, about 57 g / m2 of titanium, about 58 g / m2 of titanium, about 59 g / m2 of titanium, about 60 g / m2 of titanium, about 61 g / m2 of titanium, about 62 g / m2 of titanium, about 63 g / m2 of titanium, about 64 g / m2 of titanium, about 65 g / m2 of titanium, about 66 g / m2 of titanium, about 67 g / m2 of titanium, about 68 g / m2 of titanium, about 69 g / m2 of titanium, about 70 g / m2 of titanium, about 71 g / m2 of titanium, about 72 g / m2 of titanium, about 73 g / m2 of titanium, about 74 g / m2 of titanium, about 75 g / m2 of titanium, about 76 g / m2 of titanium, about 77 g / m2 of titanium, about 78 g / m2 of titanium, about 79 g / m2 of titanium, about 80 g / m2 of titanium, about 81 g / m2 of titanium, about 82 g / m2 of titanium, about 83 g / m2 of titanium, about 84 g / m2 of titanium, about 85 g / m2 of titanium, about 86 g / m2 of titanium, about 87 g / m2 of titanium, about 88 g / m2 of titanium, about 89 g / m2 of titanium, about 20 g / m2 of titanium, about 91 g / m2 of titanium, about 92 g / m2 of titanium, about 93 g / m2 of titanium, about 94 g / m2 of titanium, about 95 g / m2 of titanium, about 96 g / m2 of titanium, about 97 g / m2 of titanium, about 98 g / m2 of titanium, about 99 g / m2 of titanium, or about 100 g / m2 of titanium.

[0064] The first coating may include about 0.1 g / m2 to about 100 g / m2 iridium, e.g., about 1 g / m2 to about 10 g / m2 iridium, about 5 g / m2 to about 15 g / m2 iridium, about 10 g / m2 to about 20 g / m2 iridium, about 15 g / m2 to about 25 g / m2 iridium, about 20 g / m2 to about 30 g / m2 iridium, about 25 g / m2 to about 35 g / m2 iridium, about 30 g / m2 to about 40 g / m2 iridium, about 35 g / m2 to about 45 g / m2 iridium, about 40 g / m2 to about 50 g / m2 iridium, about 45 g / m2 to about 55 g / m2 iridium, about 50 g / m2 to about 60 g / m2 iridium, about 55 g / m2 to about 65 g / m2 iridium, about 60 g / m2 to about 70 g / m2 iridium, about 65 g / m2 to about 75 g / m2 iridium, about 70 g / m2 to about 80 g / m2 iridium, about 75 g / m2 to about 85 g / m2 iridium, about 80 g / m2 to about 90 g / m2 iridium, about 85 g / m2 to about 95 g / m2 iridium, or about 90 g / m2 to about 100 g / m2 iridium.

[0065] In some embodiments, the first coating may include about 0.1 g / m2 of iridium, about 0.2 g / m2 of iridium, about 0.3 g / m2 of iridium, about 0.4 g / m2 of iridium, about 0.5 g / m2 of iridium, about 0.6 g / m2 of iridium, about 0.7 g / m2 of iridium, about 0.8 g / m2 of iridium, about 0.9 g / m2 of iridium, about 1 g / m2 of iridium, about 2 g / m2 of iridium, about 3 g / m2 of iridium, about 4 g / m2 of iridium, about 5 g / m2 of iridium, about 6 g / m2 of iridium, about 7 g / m2 of iridium, about 8 g / m2 of iridium, about 9 g / m2 of iridium, about 10 g / m2 of iridium, about 11 g / m2 of iridium, about 12 g / m2 of iridium, about 13 g / m2 of iridium, about 14 g / m2 of iridium, about 15 g / m2 of iridium, about 16 g / m2 of iridium, about 17 g / m2 of iridium, about 18 g / m2 of iridium, about 19 g / m2 of iridium, about 20 g / m2 of iridium, about 21 g / m2 of iridium, about 22 g / m2 of iridium, about 23 g / m2 of iridium, about 24 g / m2 of iridium, about 25 g / m2 of iridium, about 26 g / m2 of iridium, about 27 g / m2 of iridium, about 28 g / m2 of iridium, about 29 g / m2 of iridium, about 30 g / m2 of iridium, about 31 g / m2 of iridium, about 32 g / m2 of iridium, about 33 g / m2 of iridium, about 34 g / m2 of iridium, about 35 g / m2 of iridium, about 36 g / m2 of iridium, about 37 g / m2 of iridium, about 38 g / m2 of iridium, about 39 g / m2 of iridium, about 40 g / m2 of iridium, about 41 g / m2 of iridium, about 42 g / m2 of iridium, about 43 g / m2 of iridium, about 44 g / m2 of iridium, about 45 g / m2 of iridium, about 46 g / m2 of iridium, about 47 g / m2 of iridium, about 48 g / m2 of iridium, about 49 g / m2 of iridium, about 50 g / m2 of iridium, about 51 g / m2 of iridium, about 52 g / m2 of iridium, about 53 g / m2 of iridium, about 54 g / m2 of iridium, about 55 g / m2 of iridium, about 56 g / m2 of iridium, about 57 g / m2 of iridium, about 58 g / m2 of iridium, about 59 g / m2 of iridium, about 60 g / m2 of iridium, about 61 g / m2 of iridium, about 62 g / m2 of iridium, about 63 g / m2 of iridium, about 64 g / m2 of iridium, about 65 g / m2 of iridium, about 66 g / m2 of iridium, about 67 g / m2 of iridium, about 68 g / m2 of iridium, about 69 g / m2 of iridium, about 70 g / m2 of iridium, about 71 g / m2 of iridium, about 72 g / m2 of iridium, about 73 g / m2 of iridium, about 74 g / m2 of iridium, about 75 g / m2 of iridium, about 76 g / m2 of iridium, about 77 g / m2 of iridium, about 78 g / m2 of iridium, about 79 g / m2 of iridium, about 80 g / m2 of iridium, about 81 g / m2 of iridium, about 82 g / m2 of iridium, about 83 g / m2 of iridium, about 84 g / m2 of iridium, about 85 g / m2 of iridium, about 86 g / m2 of iridium, about 87 g / m2 of iridium, about 88 g / m2 of iridium, about 89 g / m2 of iridium, about 20 g / m2 of iridium, about 91 g / m2 of iridium, about 92 g / m2 of iridium, about 93 g / m2 of iridium, about 94 g / m2 of iridium, about 95 g / m2 of iridium, about 96 g / m2 of iridium, about 97 g / m2 of iridium, about 98 g / m2 of iridium, about 99 g / m2 of iridium, or about 100 g / m2 of iridium.

[0066] The first coating may include about 0.1 g / m2 to about 100 g / m2 platinum, e.g., about 1 g / m2 to about 10 g / m2 platinum, about 5 g / m2 to about 15 g / m2 platinum, about 10 g / m2 to about 20 g / m2 platinum, about 15 g / m2 to about 25 g / m2 platinum, about 20 g / m2 to about 30 g / m2 platinum, about 25 g / m2 to about 35 g / m2 platinum, about 30 g / m2 to about 40 g / m2 platinum, about 35 g / m2 to about 45 g / m2 platinum, about 40 g / m2 to about 50 g / m2 platinum, about 45 g / m2 to about 55 g / m2 platinum, about 50 g / m2 to about 60 g / m2 platinum, about 55 g / m2 to about 65 g / m2 platinum, about 60 g / m2 to about 70 g / m2 platinum, about 65 g / m2 to about 75 g / m2 platinum, about 70 g / m2 to about 80 g / m2 platinum, about 75 g / m2 to about 85 g / m2 platinum, about 80 g / m2 to about 90 g / m2 platinum, about 85 g / m2 to about 95 g / m2 platinum, or about 90 g / m2 to about 100 g / m2 platinum.

[0067] In some embodiments, the first coating may include about 0.1 g / m2 of platinum, about 0.2 g / m2 of platinum, about 0.3 g / m2 of platinum, about 0.4 g / m2 of platinum, about 0.5 g / m2 of platinum, about 0.6 g / m2 of platinum, about 0.7 g / m2 of platinum, about 0.8 g / m2 of platinum, about 0.9 g / m2 of platinum, about 1 g / m2 of platinum, about 2 g / m2 of platinum, about 3 g / m2 of platinum, about 4 g / m2 of platinum, about 5 g / m2 of platinum, about 6 g / m2 of platinum, about 7 g / m2 of platinum, about 8 g / m2 of platinum, about 9 g / m2 of platinum, about 10 g / m2 of platinum, about 11 g / m2 of platinum, about 12 g / m2 of platinum, about 13 g / m2 of platinum, about 14 g / m2 of platinum, about 15 g / m2 of platinum, about 16 g / m2 of platinum, about 17 g / m2 of platinum, about 18 g / m2 of platinum, about 19 g / m2 of platinum, about 20 g / m2 of platinum, about 21 g / m2 of platinum, about 22 g / m2 of platinum, about 23 g / m2 of platinum, about 24 g / m2 of platinum, about 25 g / m2 of platinum, about 26 g / m2 of platinum, about 27 g / m2 of platinum, about 28 g / m2 of platinum, about 29 g / m2 of platinum, about 30 g / m2 of platinum, about 31 g / m2 of platinum, about 32 g / m2 of platinum, about 33 g / m2 of platinum, about 34 g / m2 of platinum, about 35 g / m2 of platinum, about 36 g / m2 of platinum, about 37 g / m2 of platinum, about 38 g / m2 of platinum, about 39 g / m2 of platinum, about 40 g / m2 of platinum, about 41 g / m2 of platinum, about 42 g / m2 of platinum, about 43 g / m2 of platinum, about 44 g / m2 of platinum, about 45 g / m2 of platinum, about 46 g / m2 of platinum, about 47 g / m2 of platinum, about 48 g / m2 of platinum, about 49 g / m2 of platinum, about 50 g / m2 of platinum, about 51 g / m2 of platinum, about 52 g / m2 of platinum, about 53 g / m2 of platinum, about 54 g / m2 of platinum, about 55 g / m2 of platinum, about 56 g / m2 of platinum, about 57 g / m2 of platinum, about 58 g / m2 of platinum, about 59 g / m2 of platinum, about 60 g / m2 of platinum, about 61 g / m2 of platinum, about 62 g / m2 of platinum, about 63 g / m2 of platinum, about 64 g / m2 of platinum, about 65 g / m2 of platinum, about 66 g / m2 of platinum, about 67 g / m2 of platinum, about 68 g / m2 of platinum, about 69 g / m2 of platinum, about 70 g / m2 of platinum, about 71 g / m2 of platinum, about 72 g / m2 of platinum, about 73 g / m2 of platinum, about 74 g / m2 of platinum, about 75 g / m2 of platinum, about 76 g / m2 of platinum, about 77 g / m2 of platinum, about 78 g / m2 of platinum, about 79 g / m2 of platinum, about 80 g / m2 of platinum, about 81 g / m2 of platinum, about 82 g / m2 of platinum, about 83 g / m2 of platinum, about 84 g / m2 of platinum, about 85 g / m2 of platinum, about 86 g / m2 of platinum, about 87 g / m2 of platinum, about 88 g / m2 of platinum, about 89 g / m2 of platinum, about 20 g / m2 of platinum, about 91 g / m2 of platinum, about 92 g / m2 of platinum, about 93 g / m2 of platinum, about 94 g / m2 of platinum, about 95 g / m2 of platinum, about 96 g / m2 of platinum, about 97 g / m2 of platinum, about 98 g / m2 of platinum, about 99 g / m2 of platinum, or about 100 g / m2 of platinum.

[0068] In some embodiments, the first coating has a thickness of about 100 nm to about 2000 nm, e.g., about 100 nm to about 250 nm, about 200 nm to about 350 nm, about 300 nm to about 450 nm, about 400 nm to about 550 nm, about 500 nm to about 650 nm, about 600 nm to about 750 nm, about 700 nm to about 850 nm, about 800 nm to about 950 nm, about 1000 nm to about 1150 nm, about 1100 nm to about 1250 nm, about 1200 nm to about 1350 nm, about 1300 nm to about 1450 nm, about 1400 nm to about 1550 nm, about 1500 nm to about 1650 nm, about 1600 nm to about 1750 nm, about 1700 nm to about 1850 nm, or about 1800 nm to about 200 nm. In some embodiments, the first layer has a thickness of about 100 nm, about 150 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 450 nm, about 500 nm, about 550 nm, about 600 nm, about 650 nm, about 700 nm, about 750 nm, about 800 nm, about 850 nm, about 900 nm, about 950 nm, about 1000 nm, about 1050 nm, about 1100 nm, about 1150 nm, about 1200 nm, about 1250 nm, about 1300 nm, about 1350 nm, about 1400 nm, about 1450 nm, about 1500 nm, about 1550 nm, about 1600 nm, about 1650 nm, about 1700 nm, about 1750 nm, about 1800 nm, about 1850 nm, about 1900 nm, about 1950 nm, or about 2000 nm. The thickness of the first coating may be independent of the dimensions of the electrode.

[0069] The second coating may be substantially iridium. The second coating may comprise a mixture of iridium and tantalum. In some embodiments, the second coating may consist essentially of a mixture of iridium and tantalum. In some embodiments, the second coating may consist of iridium and tantalum. Iridium may be in any weight concentration or molar ration such that a desired property is achieved. The weight concentration of iridium is the weight of iridium compared to the weight of another component in the same layer. In some embodiments, the weight concentration of iridium is within a range of 40 wt. % to 75 wt. %. In some aspects, the weight concentration of iridium is about 65 wt. %. In some embodiments, the molar ratio of iridium to tantalum in the second coating is about 2:1 to about 9:1. For example, the molar ratio of iridium to tantalum in the second coating is about 2:1, about 2.5:1, about 3:1, about 3.5:1, about 4:1, about 4.5:1, about 5:1, about 5.5:1, about 6:1, about 6.5:1, about 7:1, about 7.5:1, about 8:1, about 8.5:1, or about 9:1.

[0070] In some embodiments, the second coating may be substantially platinum. In some embodiments, platinum as a second coating may be deposited using any method disclosed herein, e.g., sALD and / or electrodeposition. Platinum may be in any weight concentration or molar ration such that a desired property is achieved. The weight concentration of platinum is the weight of platinum compared to the weight of another component in the same layer. In some embodiments, the weight concentration of platinum is within a range of 40 wt. % to 75 wt. %. In some aspects, the weight concentration of platinum is about 65 wt. %.

[0071] The second coating may include about 0.1 g / m2 to about 100 g / m2 tantalum. For example, the second coating may include about 1 g / m2 to about 100 g / m2 tantalum, e.g., about 1 g / m2 to about 10 g / m2 tantalum, about 5 g / m2 to about 15 g / m2 tantalum, about 10 g / m2 to about 20 g / m2 tantalum, about 15 g / m2 to about 25 g / m2 tantalum, about 20 g / m2 to about 30 g / m2 tantalum, about 25 g / m2 to about 35 g / m2 tantalum, about 30 g / m2 to about 40 g / m2 tantalum, about 35 g / m2 to about 45 g / m2 tantalum, about 40 g / m2 to about 50 g / m2 tantalum, about 45 g / m2 to about 55 g / m2 tantalum, about 50 g / m2 to about 60 g / m2 tantalum, about 55 g / m2 to about 65 g / m2 tantalum, about 60 g / m2 to about 70 g / m2 tantalum, about 65 g / m2 to about 75 g / m2 tantalum, about 70 g / m2 to about 80 g / m2 tantalum, about 75 g / m2 to about 85 g / m2 tantalum, about 80 g / m2 to about 90 g / m2 tantalum, about 85 g / m2 to about 95 g / m2 tantalum, or about 90 g / m2 to about 100 g / m2 tantalum.

[0072] In some embodiments, the second coating may include about 0.1 g / m2 of tantalum, about 0.2 g / m2 of tantalum, about 0.3 g / m2 of tantalum, about 0.4 g / m2 of tantalum, about 0.5 g / m2 of tantalum, about 0.6 g / m2 of tantalum, about 0.7 g / m2 of tantalum, about 0.8 g / m2 of tantalum, about 0.9 g / m2 of tantalum, about 1 g / m2 of tantalum, about 2 g / m2 of tantalum, about 3 g / m2 of tantalum, about 4 g / m2 of tantalum, about 5 g / m2 of tantalum, about 6 g / m2 of tantalum, about 7 g / m2 of tantalum, about 8 g / m2 of tantalum, about 9 g / m2 of tantalum, about 10 g / m2 of tantalum, about 11 g / m2 of tantalum, about 12 g / m2 of tantalum, about 13 g / m2 of tantalum, about 14 g / m2 of tantalum, about 15 g / m2 of tantalum, about 16 g / m2 of tantalum, about 17 g / m2 of tantalum, about 18 g / m2 of tantalum, about 19 g / m2 of tantalum, about 20 g / m2 of tantalum, about 21 g / m2 of tantalum, about 22 g / m2 of tantalum, about 23 g / m2 of tantalum, about 24 g / m2 of tantalum, about 25 g / m2 of tantalum, about 26 g / m2 of tantalum, about 27 g / m2 of tantalum, about 28 g / m2 of tantalum, about 29 g / m2 of tantalum, about 30 g / m2 of tantalum, about 31 g / m2 of tantalum, about 32 g / m2 of tantalum, about 33 g / m2 of tantalum, about 34 g / m2 of tantalum, about 35 g / m2 of tantalum, about 36 g / m2 of tantalum, about 37 g / m2 of tantalum, about 38 g / m2 of tantalum, about 39 g / m2 of tantalum, about 40 g / m2 of tantalum, about 41 g / m2 of tantalum, about 42 g / m2 of tantalum, about 43 g / m2 of tantalum, about 44 g / m2 of tantalum, about 45 g / m2 of tantalum, about 46 g / m2 of tantalum, about 47 g / m2 of tantalum, about 48 g / m2 of tantalum, about 49 g / m2 of tantalum, about 50 g / m2 of tantalum, about 51 g / m2 of tantalum, about 52 g / m2 of tantalum, about 53 g / m2 of tantalum, about 54 g / m2 of tantalum, about 55 g / m2 of tantalum, about 56 g / m2 of tantalum, about 57 g / m2 of tantalum, about 58 g / m2 of tantalum, about 59 g / m2 of tantalum, about 60 g / m2 of tantalum, about 61 g / m2 of tantalum, about 62 g / m2 of tantalum, about 63 g / m2 of tantalum, about 64 g / m2 of tantalum, about 65 g / m2 of tantalum, about 66 g / m2 of tantalum, about 67 g / m2 of tantalum, about 68 g / m2 of tantalum, about 69 g / m2 of tantalum, about 70 g / m2 of tantalum, about 71 g / m2 of tantalum, about 72 g / m2 of tantalum, about 73 g / m2 of tantalum, about 74 g / m2 of tantalum, about 75 g / m2 of tantalum, about 76 g / m2 of tantalum, about 77 g / m2 of tantalum, about 78 g / m2 of tantalum, about 79 g / m2 of tantalum, about 80 g / m2 of tantalum, about 81 g / m2 of tantalum, about 82 g / m2 of tantalum, about 83 g / m2 of tantalum, about 84 g / m2 of tantalum, about 85 g / m2 of tantalum, about 86 g / m2 of tantalum, about 87 g / m2 of tantalum, about 88 g / m2 of tantalum, about 89 g / m2 of tantalum, about 20 g / m2 of tantalum, about 91 g / m2 of tantalum, about 92 g / m2 of tantalum, about 93 g / m2 of tantalum, about 94 g / m2 of tantalum, about 95 g / m2 of tantalum, about 96 g / m2 of tantalum, about 97 g / m2 of tantalum, about 98 g / m2 of tantalum, about 99 g / m2 of tantalum, or about 100 g / m2 of tantalum.

[0073] The second coating may include about 0.1 g / m2 to about 100 g / m2 ruthenium, e.g., about 1 g / m2 to about 10 g / m2 ruthenium, about 5 g / m2 to about 15 g / m2 ruthenium, about 10 g / m2 to about 20 g / m2 ruthenium, about 15 g / m2 to about 25 g / m2 ruthenium, about 20 g / m2 to about 30 g / m2 ruthenium, about 25 g / m2 to about 35 g / m2 ruthenium, about 30 g / m2 to about 40 g / m2 ruthenium, about 35 g / m2 to about 45 g / m2 ruthenium, about 40 g / m2 to about 50 g / m2 ruthenium, about 45 g / m2 to about 55 g / m2 ruthenium, about 50 g / m2 to about 60 g / m2 ruthenium, about 55 g / m2 to about 65 g / m2 ruthenium, about 60 g / m2 to about 70 g / m2 ruthenium, about 65 g / m2 to about 75 g / m2 ruthenium, about 70 g / m2 to about 80 g / m2 ruthenium, about 75 g / m2 to about 85 g / m2 ruthenium, about 80 g / m2 to about 90 g / m2 ruthenium, about 85 g / m2 to about 95 g / m2 ruthenium, or about 90 g / m2 to about 100 g / m2 ruthenium.

[0074] In some embodiments, the second coating may include about 0.1 g / m2 of ruthenium, about 0.2 g / m2 of ruthenium, about 0.3 g / m2 of ruthenium, about 0.4 g / m2 of ruthenium, about 0.5 g / m2 of ruthenium, about 0.6 g / m2 of ruthenium, about 0.7 g / m2 of ruthenium, about 0.8 g / m2 of ruthenium, about 0.9 g / m2 of ruthenium, about 1 g / m2 of ruthenium, about 2 g / m2 of ruthenium, about 3 g / m2 of ruthenium, about 4 g / m2 of ruthenium, about 5 g / m2 of ruthenium, about 6 g / m2 of ruthenium, about 7 g / m2 of ruthenium, about 8 g / m2 of ruthenium, about 9 g / m2 of ruthenium, about 10 g / m2 of ruthenium, about 11 g / m2 of ruthenium, about 12 g / m2 of ruthenium, about 13 g / m2 of ruthenium, about 14 g / m2 of ruthenium, about 15 g / m2 of ruthenium, about 16 g / m2 of ruthenium, about 17 g / m2 of ruthenium, about 18 g / m2 of ruthenium, about 19 g / m2 of ruthenium, about 20 g / m2 of ruthenium, about 21 g / m2 of ruthenium, about 22 g / m2 of ruthenium, about 23 g / m2 of ruthenium, about 24 g / m2 of ruthenium, about 25 g / m2 of ruthenium, about 26 g / m2 of ruthenium, about 27 g / m2 of ruthenium, about 28 g / m2 of ruthenium, about 29 g / m2 of ruthenium, about 30 g / m2 of ruthenium, about 31 g / m2 of ruthenium, about 32 g / m2 of ruthenium, about 33 g / m2 of ruthenium, about 34 g / m2 of ruthenium, about 35 g / m2 of ruthenium, about 36 g / m2 of ruthenium, about 37 g / m2 of ruthenium, about 38 g / m2 of ruthenium, about 39 g / m2 of ruthenium, about 40 g / m2 of ruthenium, about 41 g / m2 of ruthenium, about 42 g / m2 of ruthenium, about 43 g / m2 of ruthenium, about 44 g / m2 of ruthenium, about 45 g / m2 of ruthenium, about 46 g / m2 of ruthenium, about 47 g / m2 of ruthenium, about 48 g / m2 of ruthenium, about 49 g / m2 of ruthenium, about 50 g / m2 of ruthenium, about 51 g / m2 of ruthenium, about 52 g / m2 of ruthenium, about 53 g / m2 of ruthenium, about 54 g / m2 of ruthenium, about 55 g / m2 of ruthenium, about 56 g / m2 of ruthenium, about 57 g / m2 of ruthenium, about 58 g / m2 of ruthenium, about 59 g / m2 of ruthenium, about 60 g / m2 of ruthenium, about 61 g / m2 of ruthenium, about 62 g / m2 of ruthenium, about 63 g / m2 of ruthenium, about 64 g / m2 of ruthenium, about 65 g / m2 of ruthenium, about 66 g / m2 of ruthenium, about 67 g / m2 of ruthenium, about 68 g / m2 of ruthenium, about 69 g / m2 of ruthenium, about 70 g / m2 of ruthenium, about 71 g / m2 of ruthenium, about 72 g / m2 of ruthenium, about 73 g / m2 of ruthenium, about 74 g / m2 of ruthenium, about 75 g / m2 of ruthenium, about 76 g / m2 of ruthenium, about 77 g / m2 of ruthenium, about 78 g / m2 of ruthenium, about 79 g / m2 of ruthenium, about 80 g / m2 of ruthenium, about 81 g / m2 of ruthenium, about 82 g / m2 of ruthenium, about 83 g / m2 of ruthenium, about 84 g / m2 of ruthenium, about 85 g / m2 of ruthenium, about 86 g / m2 of ruthenium, about 87 g / m2 of ruthenium, about 88 g / m2 of ruthenium, about 89 g / m2 of ruthenium, about 20 g / m2 of ruthenium, about 91 g / m2 of ruthenium, about 92 g / m2 of ruthenium, about 93 g / m2 of ruthenium, about 94 g / m2 of ruthenium, about 95 g / m2 of ruthenium, about 96 g / m2 of ruthenium, about 97 g / m2 of ruthenium, about 98 g / m2 of ruthenium, about 99 g / m2 of ruthenium, or about 100 g / m2 of ruthenium.

[0075] The second coating may include about 0.1 g / m2 to about 100 g / m2 iridium, e.g., about 1 g / m2 to about 10 g / m2 iridium, about 5 g / m2 to about 15 g / m2 iridium, about 10 g / m2 to about 20 g / m2 iridium, about 15 g / m2 to about 25 g / m2 iridium, about 20 g / m2 to about 30 g / m2 iridium, about 25 g / m2 to about 35 g / m2 iridium, about 30 g / m2 to about 40 g / m2 iridium, about 35 g / m2 to about 45 g / m2 iridium, about 40 g / m2 to about 50 g / m2 iridium, about 45 g / m2 to about 55 g / m2 iridium, about 50 g / m2 to about 60 g / m2 iridium, about 55 g / m2 to about 65 g / m2 iridium, about 60 g / m2 to about 70 g / m2 iridium, about 65 g / m2 to about 75 g / m2 iridium, about 70 g / m2 to about 80 g / m2 iridium, about 75 g / m2 to about 85 g / m2 iridium, about 80 g / m2 to about 90 g / m2 iridium, about 85 g / m2 to about 95 g / m2 iridium, or about 90 g / m2 to about 100 g / m2 iridium.

[0076] In some embodiments, the second coating may include about 0.1 g / m2 of iridium, about 0.2 g / m2 of iridium, about 0.3 g / m2 of iridium, about 0.4 g / m2 of iridium, about 0.5 g / m2 of iridium, about 0.6 g / m2 of iridium, about 0.7 g / m2 of iridium, about 0.8 g / m2 of iridium, about 0.9 g / m2 of iridium, about 1 g / m2 of iridium, about 2 g / m2 of iridium, about 3 g / m2 of iridium, about 4 g / m2 of iridium, about 5 g / m2 of iridium, about 6 g / m2 of iridium, about 7 g / m2 of iridium, about 8 g / m2 of iridium, about 9 g / m2 of iridium, about 10 g / m2 of iridium, about 11 g / m2 of iridium, about 12 g / m2 of iridium, about 13 g / m2 of iridium, about 14 g / m2 of iridium, about 15 g / m2 of iridium, about 16 g / m2 of iridium, about 17 g / m2 of iridium, about 18 g / m2 of iridium, about 19 g / m2 of iridium, about 20 g / m2 of iridium, about 21 g / m2 of iridium, about 22 g / m2 of iridium, about 23 g / m2 of iridium, about 24 g / m2 of iridium, about 25 g / m2 of iridium, about 26 g / m2 of iridium, about 27 g / m2 of iridium, about 28 g / m2 of iridium, about 29 g / m2 of iridium, about 30 g / m2 of iridium, about 31 g / m2 of iridium, about 32 g / m2 of iridium, about 33 g / m2 of iridium, about 34 g / m2 of iridium, about 35 g / m2 of iridium, about 36 g / m2 of iridium, about 37 g / m2 of iridium, about 38 g / m2 of iridium, about 39 g / m2 of iridium, about 40 g / m2 of iridium, about 41 g / m2 of iridium, about 42 g / m2 of iridium, about 43 g / m2 of iridium, about 44 g / m2 of iridium, about 45 g / m2 of iridium, about 46 g / m2 of iridium, about 47 g / m2 of iridium, about 48 g / m2 of iridium, about 49 g / m2 of iridium, about 50 g / m2 of iridium, about 51 g / m2 of iridium, about 52 g / m2 of iridium, about 53 g / m2 of iridium, about 54 g / m2 of iridium, about 55 g / m2 of iridium, about 56 g / m2 of iridium, about 57 g / m2 of iridium, about 58 g / m2 of iridium, about 59 g / m2 of iridium, about 60 g / m2 of iridium, about 61 g / m2 of iridium, about 62 g / m2 of iridium, about 63 g / m2 of iridium, about 64 g / m2 of iridium, about 65 g / m2 of iridium, about 66 g / m2 of iridium, about 67 g / m2 of iridium, about 68 g / m2 of iridium, about 69 g / m2 of iridium, about 70 g / m2 of iridium, about 71 g / m2 of iridium, about 72 g / m2 of iridium, about 73 g / m2 of iridium, about 74 g / m2 of iridium, about 75 g / m2 of iridium, about 76 g / m2 of iridium, about 77 g / m2 of iridium, about 78 g / m2 of iridium, about 79 g / m2 of iridium, about 80 g / m2 of iridium, about 81 g / m2 of iridium, about 82 g / m2 of iridium, about 83 g / m2 of iridium, about 84 g / m2 of iridium, about 85 g / m2 of iridium, about 86 g / m2 of iridium, about 87 g / m2 of iridium, about 88 g / m2 of iridium, about 89 g / m2 of iridium, about 20 g / m2 of iridium, about 91 g / m2 of iridium, about 92 g / m2 of iridium, about 93 g / m2 of iridium, about 94 g / m2 of iridium, about 95 g / m2 of iridium, about 96 g / m2 of iridium, about 97 g / m2 of iridium, about 98 g / m2 of iridium, about 99 g / m2 of iridium, or about 100 g / m2 of iridium.

[0077] The second coating may include about 0.1 g / m2 to about 200 g / m2 platinum, e.g., about 1 g / m2 to about 10 g / m2 platinum, about 5 g / m2 to about 15 g / m2 platinum, about 10 g / m2 to about 20 g / m2 platinum, about 15 g / m2 to about 25 g / m2 platinum, about 20 g / m2 to about 30 g / m2 platinum, about 25 g / m2 to about 35 g / m2 platinum, about 30 g / m2 to about 40 g / m2 platinum, about 35 g / m2 to about 45 g / m2 platinum, about 40 g / m2 to about 50 g / m2 platinum, about 45 g / m2 to about 55 g / m2 platinum, about 50 g / m2 to about 60 g / m2 platinum, about 55 g / m2 to about 65 g / m2 platinum, about 60 g / m2 to about 70 g / m2 platinum, about 65 g / m2 to about 75 g / m2 platinum, about 70 g / m2 to about 80 g / m2 platinum, about 75 g / m2 to about 85 g / m2 platinum, about 80 g / m2 to about 90 g / m2 platinum, about 85 g / m2 to about 95 g / m2 platinum, about 90 g / m2 to about 100 g / m2 platinum, about 110 g / m2 to about 120 g / m2 platinum, about 115 g / m2 to about 125 g / m2 platinum, about 210 g / m2 to about 130 g / m2 platinum, about 125 g / m2 to about 135 g / m2 platinum, about 130 g / m2 to about 140 g / m2 platinum, about 135 g / m2 to about 145 g / m2 platinum, about 140 g / m2 to about 150 g / m2 platinum, about 145 g / m2 to about 155 g / m2 platinum, about 150 g / m2 to about 160 g / m2 platinum, about 155 g / m2 to about 165 g / m2 platinum, about 160 g / m2 to about 170 g / m2 platinum, about 165 g / m2 to about 175 g / m2 platinum, about 170 g / m2 to about 180 g / m2 platinum, about 175 g / m2 to about 185 g / m2 platinum, about 180 g / m2 to about 190 g / m2 platinum, about 185 g / m2 to about 195 g / m2 platinum, or about 190 g / m2 to about 200 g / m2 platinum.

[0078] In some embodiments, the second coating may include about 0.1 g / m2 of platinum, about 0.2 g / m2 of platinum, about 0.3 g / m2 of platinum, about 0.4 g / m2 of platinum, about 0.5 g / m2 of platinum, about 0.6 g / m2 of platinum, about 0.7 g / m2 of platinum, about 0.8 g / m2 of platinum, about 0.9 g / m2 of platinum, about 1 g / m2 of platinum, about 2 g / m2 of platinum, about 3 g / m2 of platinum, about 4 g / m2 of platinum, about 5 g / m2 of platinum, about 6 g / m2 of platinum, about 7 g / m2 of platinum, about 8 g / m2 of platinum, about 9 g / m2 of platinum, about 10 g / m2 of platinum, about 11 g / m2 of platinum, about 12 g / m2 of platinum, about 13 g / m2 of platinum, about 14 g / m2 of platinum, about 15 g / m2 of platinum, about 16 g / m2 of platinum, about 17 g / m2 of platinum, about 18 g / m2 of platinum, about 19 g / m2 of platinum, about 20 g / m2 of platinum, about 21 g / m2 of platinum, about 22 g / m2 of platinum, about 23 g / m2 of platinum, about 24 g / m2 of platinum, about 25 g / m2 of platinum, about 26 g / m2 of platinum, about 27 g / m2 of platinum, about 28 g / m2 of platinum, about 29 g / m2 of platinum, about 30 g / m2 of platinum, about 31 g / m2 of platinum, about 32 g / m2 of platinum, about 33 g / m2 of platinum, about 34 g / m2 of platinum, about 35 g / m2 of platinum, about 36 g / m2 of platinum, about 37 g / m2 of platinum, about 38 g / m2 of platinum, about 39 g / m2 of platinum, about 40 g / m2 of platinum, about 41 g / m2 of platinum, about 42 g / m2 of platinum, about 43 g / m2 of platinum, about 44 g / m2 of platinum, about 45 g / m2 of platinum, about 46 g / m2 of platinum, about 47 g / m2 of platinum, about 48 g / m2 of platinum, about 49 g / m2 of platinum, about 50 g / m2 of platinum, about 51 g / m2 of platinum, about 52 g / m2 of platinum, about 53 g / m2 of platinum, about 54 g / m2 of platinum, about 55 g / m2 of platinum, about 56 g / m2 of platinum, about 57 g / m2 of platinum, about 58 g / m2 of platinum, about 59 g / m2 of platinum, about 60 g / m2 of platinum, about 61 g / m2 of platinum, about 62 g / m2 of platinum, about 63 g / m2 of platinum, about 64 g / m2 of platinum, about 65 g / m2 of platinum, about 66 g / m2 of platinum, about 67 g / m2 of platinum, about 68 g / m2 of platinum, about 69 g / m2 of platinum, about 70 g / m2 of platinum, about 71 g / m2 of platinum, about 72 g / m2 of platinum, about 73 g / m2 of platinum, about 74 g / m2 of platinum, about 75 g / m2 of platinum, about 76 g / m2 of platinum, about 77 g / m2 of platinum, about 78 g / m2 of platinum, about 79 g / m2 of platinum, about 80 g / m2 of platinum, about 81 g / m2 of platinum, about 82 g / m2 of platinum, about 83 g / m2 of platinum, about 84 g / m2 of platinum, about 85 g / m2 of platinum, about 86 g / m2 of platinum, about 87 g / m2 of platinum, about 88 g / m2 of platinum, about 89 g / m2 of platinum, about 20 g / m2 of platinum, about 91 g / m2 of platinum, about 92 g / m2 of platinum, about 93 g / m2 of platinum, about 94 g / m2 of platinum, about 95 g / m2 of platinum, about 96 g / m2 of platinum, about 97 g / m2 of platinum, about 98 g / m2 of platinum, about 99 g / m2 of platinum, about 100 g / m2 of platinum, about 105 g / m2 of platinum, about 110 g / m2 of platinum, about 105 g / m2 of platinum, about 110 g / m2 of platinum, about 105 g / m2 of platinum, about 110 g / m2 of platinum, about 115 g / m2 of platinum, about 120 g / m2 of platinum, about 125 g / m2 of platinum, about 130 g / m2 of platinum, about 135 g / m2 of platinum, about 140 g / m2 of platinum, about 145 g / m2 of platinum, about 150 g / m2 of platinum, about 155 g / m2 of platinum, about 160 g / m2 of platinum, about 165 g / m2 of platinum, about 170 g / m2 of platinum, about 175 g / m2 of platinum, about 180 g / m2 of platinum, about 185 g / m2 of platinum, about 190 g / m2 of platinum, about 195 g / m2 of platinum, or about 200 g / m2 of platinum.

[0079] In some embodiments, the second coating as a thickness of about 10 nm to about 100 nm, e.g., about 10 nm to about 20 nm, about 15 nm to about 25 nm, about 20 nm to about 30 nm, about 25 nm to about 35 nm, about 30 nm to about 40 nm, about 35 nm to about 45 nm, about 40 nm to about 50 nm, about 45 nm to about 55 nm, about 50 nm to about 60 nm, about 55 nm to about 65 nm, about 60 nm to about 70 nm, about 65 nm to about 75 nm, about 70 nm to about 80 nm, about 75 nm to about 85 nm, about 80 nm to about 90 nm, about 85 nm to about 95 nm, or about 90 nm to about 100 nm. In some embodiments, the second coating has a thickness of, about 10 nm, about 11 nm, about 12 nm, about 13 nm, about 14 nm, about 15 nm, about 16 nm, about 17 nm, about 18 nm, about 19 nm, about 20 nm, about 21 nm, about 22 nm, about 23 nm, about 24 nm, about 25 nm, about 26 nm, about 27 nm, about 28 nm, about 29 nm, about 30 nm, about 31 nm, about 32 nm, about 33 nm, about 34 nm, about 35 nm, about 36 nm, about 37 nm, about 38 nm, about 39 nm, about 40 nm, about 41 nm, about 42 nm, about 43 nm, about 44 nm, about 45 nm, about 46 nm, about 47 nm, about 48 nm, about 49 nm, about 50 nm, about 51 nm, about 52 nm, about 53 nm, about 54 nm, about 55 nm, about 56 nm, about 57 nm, about 58 nm, about 59 nm, about 60 nm, about 61 nm, about 62 nm, about 63 nm, about 64 nm, about 65 nm, about 66 nm, about 67 nm, about 68 nm, about 69 nm, about 70 nm, about 71 nm, about 72 nm, about 73 nm, about 74 nm, about 75 nm, about 76 nm, about 77 nm, about 78 nm, about 79 nm, about 80 nm, about 81 nm, about 82 nm, about 83 nm, about 84 nm, about 85 nm, about 86 nm, about 87 nm, about 88 nm, about 89 nm, about 20 nm, about 91 nm, about 92 nm, about 93 nm, about 94 nm, about 95 nm, about 96 nm, about 97 nm, about 98 nm, about 99 nm, or about 100 nm. The thickness of the second coating may be independent of the dimensions of the electrode.

[0080] The combination of chemical elements, coating thickness, and coating uniformity may provide for improvements in one or more properties of the electrodes, e.g., catalytic activity, durability, and the like. For example, electrodes of this disclosure can provide for about a 300% improvement in durability than an electrode comprising a single layer coating consisting of a composition of the second coating. In a non-limiting example, the durability of an electrode may be assessed by performance of the electrode with and without a deposited interlayer under galvanostatic conditions. The time necessary for an electrode to reach a certain potential on the working electrode provides an indication of the lifetime of the electrode. As disclosed herein, an electrode having both a first coating and a second coating generally is more durable than an electrode with a single coating. In other embodiments, electrodes of this disclosure provide for about a 50% greater activity, e.g., catalytic activity, e.g., oxygen evolution reaction activity, than an electrode comprising a single layer coating consisting of a composition of the second coating. Similarly, the behavior of an electrode as determined by a current-voltage diagram, i.e., an I-V curve, can be used to determine if an electrode coating has an effect on an electrochemical reaction. In general, an electrode is considered to be more active if and I-V curve has a steeper slope, i.e., greater current at a lower voltage in the electrochemical cell. As disclosed herein, an electrode having both a first coating and a second coating generally exhibits an increased activity for one or more electrochemical reactions than an electrode with a single coating as determined by the steepness of the curve as a voltage is swept.

[0081] The electrode substrate may be applied with, for example, coated with the first and second coatings according to any application process, e.g., physical application, chemical application, or magnetron sputtering, that may provide for a homogeneous or substantially homogeneous dispersal of material to the desired surface. For example, the first and second coatings may be applied to the electrode substrate by brushing, rolling, dipping, spraying, or by atomic or molecular layer deposition, or the like. The electrode substrate may be coated with the first and second coating mixtures according to a thermal decomposition method. For example, the first coating to second coating may be applied by dissolving the metal precursor in a solvent, applying the dissolved precursor to the substrate, and evaporating the solvent. The electrode substrate may be coated with the first and second coating mixtures according to an atomic layer deposition process. For example, one or both of the first coating and second coating may be applied using sALD.

[0082] The electrode substrate may first be prepared for application of a coating. For example, the electrode substrate may be treated or cleaned to accept the coating, or to provide for a surface that may be susceptible to adherence of a coating. Cleaning of the electrode substrate may be performed by a laser treatment, chemical baths, e.g., chemical degreasing, electrolytic degreasing, or treatment with an oxidizing acid. Chemical degreasing may be performed using a polar solvent, such as acetone, acetonitrile, dimethylformamide (DMF), dimelthylsulfoxide (DMSO), isopropanol, and methanol. Suitable acids used to treat electrode surfaces include haloacids such as HCl and organic acids such as oxalic acid. In some embodiments, the electrode substrate may be pretreated using one or more plasma treatments. As a non-limiting example, an electrode substrate may first be treated with an oxidative plasma to remove impurities from the surface followed by a reducing plasma to remove any residual oxides from the surface. The electrode substrate may be prepared by any method suitable to remove or minimize contaminants and develop high surface roughness that may hinder proper adhesion of the coating to the surface of the substrate and lower the effective current density for coated metal surfaces, thus also decreasing the electrode operating potential. Longer lived anodes translate into less down time and cell maintenance, thereby cutting operating cost. For example, the electrode substrate may be prepared by a cleaning, sandblasting, etching, and / or pre-oxidation process. Other methods of preparing the electrode substrate may include plasma spraying, melt spraying with ceramic oxide particles, melt spraying of a valve metal layer onto the electrode substrate, grit blasting with a sharp grit, and annealing. Cleaning of the electrode substrate may be followed by mechanical or chemical roughening to prepare the surface for coating. In some embodiments, when the cleaning is performed via sandblasting, it may be followed by an etching process.

[0083] In accordance with an aspect, there is provided a method of preparing an electrode. The method includes applying a first coating comprising one or more of platinum, iridium, titanium, or tantalum to a surface of an electrically conductive substrate. The method includes applying a second coating comprising one or more of tantalum, iridium, platinum, or ruthenium to a surface of the first coating. The second coating has a substantially uniform composition and a thickness of less than about 100 nm.

[0084] In some embodiments, i.e., as disclosed herein, the method includes, prior to applying the first coating layer, preparing the electrically conductive substrate to remove contaminants and to develop the surface, e.g., using one or more of a chemical bath, laser treatment, oxidative plasma treatment, or reductive plasma treatment.

[0085] In some embodiments, the first coating layer is applied using physical application, chemical application, or magnetron sputtering. Following application of the first coating layer, the method includes drying the first coating layer, e.g., to remove any residual solvent. In some embodiments, the electrically conductive substrate with the first coating is heated, e.g., using an oven, furnace, or other controllable heat source, or plasma treated, e.g., using a nitrogen and / or oxygen plasma, to form oxides of the metals of the first coating.

[0086] In further embodiments, the second coating is applied to the heat-treated first coating using any suitable deposition technique disclosed herein. For example, the second coating can be applied using atomic layer deposition, e.g., sALD, e.g., in one or more passes, until an expected or desired loading of metal is achieved. Following deposition of the second coating, the electrode may be heat treated, e.g., using an oven, furnace, or other controllable heat source, or plasma treated, e.g., using a nitrogen and / or oxygen plasma, to form oxides of the metals of the second coating.

[0087] The electrode may be installed in an electrolytic cell. In an embodiment, the electrolytic cell also has a power source for supplying a current to the electrodes of the electrolytic cell. In some embodiments, the source of current may be a direct current source. In the current direction, one electrode typically acts as the anode and its counterpart typically acts as the cathode.

[0088] In accordance with an aspect, there is provided a method of manufacturing an electrolytic cell. The method includes preparing an electrode, e.g., as disclosed herein. The electrode includes an electrically conductive substrate, a first coating on a surface of the electrically conductive substrate, and a second coating on a surface of first coating. The first coating includes one or more of platinum, iridium, titanium, and tantalum. The second coating includes one or more of tantalum, iridium, platinum, or ruthenium. The second coating has a substantially uniform composition and a thickness of less than about 100 nm. The method includes installing the electrode in an electrolytic cell.

[0089] In accordance with an aspect, there is provided an electrolytic cell. The electrolytic cell includes an anode and a cathode. The electrolytic cell further includes an electrolyte layer disposed between the anode and cathode permitting transport of protons from the anode to the cathode. The electrolyte layer includes a substrate sufficient for transporting protons, a first coating on a surface of the substrate and a second coating on a surface of first coating. The first coating includes one or more of platinum, iridium, titanium, and tantalum. The second coating includes one or more of tantalum, iridium, platinum, or ruthenium. The second coating has a substantially uniform composition and a thickness of less than about 100 nm.

[0090] In accordance with an aspect, there is provided an electrolytic cell. The electrolytic cell includes an anode, e.g., as disclosed herein. The electrode includes an electrically conductive substrate, a first coating on a surface of the electrically conductive substrate, and a second coating on a surface of first coating. The first coating includes one or more of platinum, iridium, titanium, and tantalum. The second coating includes one or more of tantalum, iridium, platinum, or ruthenium. The second coating has a substantially uniform composition and a thickness of less than about 100 nm. The electrolytic cell includes a cathode. The electrolytic cell further includes an electrolyte layer disposed between the anode and cathode that permits transport of protons from the anode to the cathode, e.g., when the electrolytic cell is electrically driven.

[0091] The electrolytic cell may be part of a system and include a power source that is disposed to drive the electrolytic cell. For example, the electrolytic cell may be used in a wastewater treatment system. In some embodiments, the electrolytic cell may be used in a municipal or industrial wastewater treatment system. In some embodiments, the electrolytic cell may be used in a chemical processing system. In some embodiments, the electrolytic cell may be used in an industrial process water system. For example, the electrolytic cell may be used in an electrolytic chlorine generation system. The system may comprise a source of salt water. For example, the system may comprise a source of ballast water. In some embodiments, the system may further comprise a water outlet. For example, the system may comprise a potable water outlet. In some embodiments, the system may further comprise a water storage unit fluidly connected to the water outlet. In some embodiments, the system may further comprise a contaminant outlet. For example, the system may comprise a chlorine solution outlet. In some embodiments, the system may chlorine solution outlet may comprise a sodium hypochlorite solution outlet. In some embodiments, the system may comprise a contaminant storage unit fluidly connected to the contaminant outlet.

[0092] Referring to FIGS. 1A and 1B, a two coating electrode is provided. Electrode 100 comprises an electrically conductive substrate 101 and may be any substrate having electrically conductive properties. Substrate 101 may be a metal. In some embodiments, substrate 101 may be a valve metal. For example, substrate 101 may comprise titanium, vanadium, zirconium, niobium, hafnium, or tantalum. In some embodiments, substrate 101 is titanium. In some embodiments, substrate 101 is a membrane material, such as a fluororpolymer, e.g., a sulfonated fluoropolymer, perfluorosulfonic acid (PFSA) ionomers, or related substrates that can conduct charged species. When a membrane is used as substrate 101, the coated membrane is used as a catalytic membrane for polymer electrolyte membrane (PEM) hydrolysis. Substrate 101 may be prepared for application of a coating. For example, substrate 101 may be treated or cleaned to accept the coating, or to provide for a surface that may be susceptible to adherence of a coating. Cleaning of substrate 101 may be performed by chemical degreasing, electrolytic degreasing, or treatment with an oxidizing acid. Substrate 101 may be prepared by any method suitable to remove or minimize contaminants and develop high surface roughness that may hinder proper adhesion of a coating to the surface of substrate 101 and lower the effective current density for coated metal surfaces, thus also decreasing the electrode operating potential. For example, substrate 101 may be prepared by a cleaning, sandblasting, etching, and / or pre-oxidation process. Other methods of preparing substrate 101 may include plasma spraying, melt spraying with ceramic oxide particles, melt spraying of a valve metal layer onto the electrode substrate, grit blasting with a sharp grit, and annealing. Cleaning of substrate 101 may be followed by mechanical roughening to prepare the surface for coating. In some embodiments, when the cleaning is performed via sandblasting, it may be followed by an etching process.

[0093] Substrate 101 may be coated with a first coating 102. First coating 102 may cover at least a portion of the surface of substrate 101. First coating 102 may comprise an oxide of one or more of platinum, iridium, titanium, and tantalum. First coating 102 may comprise one or more of platinum, iridium, titanium, and tantalum in any weight concentration such that a desired property is achieved. First coating 102 may be applied to the surface of substrate 101 by any known application process.

[0094] For example, first coating 102 may be applied to the surface of substrate 101 by brushing, rolling, or spraying. First coating 102 may be applied to the surface of substrate 101 using a physio-chemical application process with a dissolved precursor in a solvent or magnetron sputtering.

[0095] First coating 102 may be coated with a second coating 103. Second coating 103 may cover at least a portion of first coating 102. Second coating 103 may comprise one or more of tantalum, iridium, platinum, or ruthenium. Second coating 103 may comprise one or more of tantalum, iridium, platinum, or ruthenium in any weight concentration such that a desired property is achieved, for example, increased catalytic activity. Second coating 103 may be applied to first coating 102 by atomic layer deposition, e.g., sALD, physical application, chemical application, i.e., a physio-chemical application process with a dissolved precursor in a solvent, or magnetron sputtering. Once applied, the second coating has a substantially uniform composition and a thickness of less than about 100 nm, e.g., as disclosed herein.

[0096] Referring now to FIG. 2, an electrochemical system, i.e., an electrolyzer, is provided. System 200 may comprise electrolytic cell 210. Electrolytic cell 210 may comprise at least one electrode 100 as described herein. Electrode 100 may be at least one of an anode and a cathode. In some embodiments, electrode 100 is an anode. In some embodiments, electrolytic cell 210 includes an electrode 100 where the substrate 101 is a membrane, i.e., a catalyst coated membrane (CCM), rather than a metallic electrode substrate. System 200 may further comprise power source 230 operably connected to electrolytic cell 210. Power source 230 may supply direct current to electrolytic cell 210.

[0097] One or more sensors 240 may be located within electrolytic cell 210. Sensor 240 may be configured to measure a quality parameter of system 200. In some embodiments, sensor 240 may be configured to measure one or more of the pH of the system (for example, pH of an electrolyte), the temperature of the system (for example, temperature of the electrolyte), conductivity of the electrolyte, and the current of the system. The sensors 240 may communicate, electrically or otherwise, with controller 250 to provide the controller with a signal indicative of the measured property of the system. Controller 250 may control one or more properties of the system. For example, controller 250 may control the amperage into the system from power source 230.

[0098] The function and advantages of these and other embodiments will be more fully understood from the following non-limiting examples. The examples are intended to be illustrative in nature and are not to be considered as limiting the scope of the embodiments discussed herein.EXAMPLES

[0099] The function and advantages of these and other embodiments can be better understood from the following examples. These examples are intended to be illustrative in nature and are not considered to be in any way limiting the scope of the present disclosure.

[0100] In the following examples, i.e., Examples 1-6 and Comparative Examples 1-2, the following parameters were used to produce coated electrode samples: the Ir precursor was Ethylcyclopentadienyl cyclohexadiene Ir ((EtCp)Ir(CHD)), the Ta precursor was Ta(Et-C═C-Et)(CI)(N)(t-Bu), and the surfaces of the samples were exposed to an N2 / O2 plasma.Comparative Example 1

[0101] A sheet of Grade 1 Ti was annealed, etched in hydrochloric acid, and subsequently rinsed. Next, a butanol-based paint containing H2IrCl6 and Ta2(OC2H5)10 was applied onto the Ti sheet in layers of 1 g / m2 of Ir using spin coating. After each layer, the butanol was evaporated and the dried paint coated sheet was placed into an electric furnace at 500° C. for 1 hour to convert the Ir and Ta into their respective oxides, i.e., IrO2 and Ta2O5. In total, three layers of the precursor paint were applied, resulting in an IrO2 / Ta2O5 MMO coating with a total Ir loading of 1.59 g / m2. A homogeneous coating was obtained.

[0102] The lifetime of the resulting Ir MMO coating was subsequently tested in 25% H2SO4 at 20,000 A / m2 and 50° C. A lifetime of 0.86 MAh / m2 was obtained.Example 1

[0103] A sheet of Grade 1 Ti was degreased with isopropanol and placed in the sALD device. The pretreatment of the Ti sheet consisted of both an HCl etching and an oxidative plasma treatment to remove any impurities from the surface followed by a reducing plasma to prepare an oxide-free Ti interface. Next, the Ir precursor (EtCp)Ir(CHD) and Ta precursor Ta(Et-C═C-Et)(CI)(N)(t-Bu) were dosed together in a single step to apply a layer onto the Ti sheet. Following deposition an N2 / O2 plasma was applied to the deposited coating to convert the metal precursors to IrO2 and Ta2O5 onto the Ti sheet surface. The metal vapor dosing and plasma steps were repeated to obtain a surface loading of 1.43 g / m2 Ir. A homogeneous coating was obtained.

[0104] The lifetime of the resulting Ir MMO coating was subsequently tested in 25% H2SO4 at 20,000 A / m2 and 50° C. A lifetime of 0.95 MAh / m2 was obtained with heat treatment after sALD deposition.Comparative Example 2

[0105] A Grade 1 porous Ti fiber felt was annealed, etched in hydrochloric acid, and subsequently rinsed. Next, a butanol-based paint containing H2IrCl6 and Ta2(OC2H5)10 was applied onto the Ti sheet in layers of 1 g / m2 of Ir using spin coating. After each layer, the butanol was evaporated and the dried paint coated sheet was placed into an electric furnace at 500° C. for 1 hour to convert the Ir and Ta into their respective oxides, i.e., IrO2 and Ta2O5. In total, three layers of the precursor paint were applied, resulting in an IrO2 / Ta2O5 MMO coating. A homogeneous coating was obtained.

[0106] The lifetime of the resulting Ir MMO coating was subsequently tested in 25% H2SO4 at 20,000 A / m2 and 50° C. A lifetime, expressed as MAh / m2, was obtained.Example 2

[0107] A sheet of Grade 1 Ti was degreased with isopropanol and placed in the sALD device. The pretreatment of the Ti sheet consisted of a HCl etch to prepare an oxide-free Ti interface. First, the Ta precursor Ta(Et-C═C-Et)(CI)(N)(t-Bu) was dosed onto the Ti sheet to form a layer of Ta, which was heat treated to form Ta2O5. The dosing and heating steps were repeated to obtain a surface loading of 1 g / m2 Ta. Next, the Ir precursor (EtCp)Ir(CHD) and Ta precursor Ta(Et-C═C-Et)(CI)(N)(t-Bu) were dissolved in butanol and applied to the sALD-applied Ta on the sample. Following application of the Ir and Ta precursors, the sample was heat treated at 500° C. for 25 minutes to convert the metal precursors to IrO2 and Ta2O5 onto the Ti sheet surface. The dissolved metal application and heating steps were repeated to obtain a surface loading of 3.85 g / m2 Ir. A homogeneous coating was obtained. The lifetime of the resulting Ir MMO coating was tested in 25% H2SO4 at 20,000 A / m2 and 50° C. and a lifetime of 10.9 MAh / m2 was obtained.

[0108] A second sample with only the applied Ir-Ta coating by butanol deposition was prepared as described above. This sample did not contain the Ta interlayer applied using sALD. Following application of the Ir and Ta precursors, the sample was heat treated at 500° C. for 25 minutes to convert the metal precursors to IrO2 and Ta2O5 onto the Ti sheet surface. The dissolved metal application and heating steps were repeated to obtain a surface loading of 3.2 g / m2 Ir. A homogeneous coating was obtained. The lifetime of the resulting Ir MMO coating was tested in 25% H2SO4 at 20,000 A / m2 and 50° C. and a lifetime of 1.45 MAh / m2 was obtained.Example 3

[0109] In this example, the coating of a Ti substrate with platinum (Pt) using spatial Atomic Layer Deposition (sALD) is explored.

[0110] A Grade 1 Ti sheet was first treated with 6M hydrochloric acid (HCl) at 90° C. for 90 minutes to both roughen and clean the Ti surface. Using an organoplatinum salt as a Pt source, Pt vapor was dosed onto the Ti sheet using sALD to form a layer of Pt on the Ti sheet. For comparative purposes, another Ti sheet was prepared using the same HCl etching and Pt coating using electrodeposition. For further comparisons, separate Ti sheets were etched using oxalic acid, typically considered state of the art for electrodeposited Pt coatings.

[0111] As illustrated in FIG. 3, the sALD Pt coating (0.107 MAh / g) exhibited twice the electrochemical performance compared to the conventional electrodeposited Pt coating with the same HCl etch pretreatment (0.048 MAh / g). Similarly, the sALD Pt coating (0.107 MAh / g) displayed about 40% improved electrochemical performance compared to the electrodeposited Pt coating with oxalic acid pretreatment (0.064 MAh / g).

[0112] In further comparisons, the electrochemical performance of the sALD Pt coating was compared to Ti sheets that included the deposition of various interlayers. As disclosed herein, interlayers are typically applied to protect the substrate from corrosion and increase the lifetime of the electrode. FIG. 4 compares the electrochemical performance of the sALD Pt coating to sample electrodes made with: a) electrodeposited Pt with a Pt / Ir interlayer; b) electrodeposited Pt with an Ir MMO interlayer, and electrodeposited Pt with a sALD Pt interlayer. As is seen in FIG. 4, the sALD Pt coating without an interlayer had the most robust electrochemical performance of the samples tested. Thus, it is believed that the use of interlayers containing expensive and scarce iridium can be substantially eliminated and therefore provide for a significant materials cost reduction and lower dependence on scarce materials.

[0113] FIGS. 5A and 5B illustrate SEM images of vertical cross-sections of the Pt coatings on a conventional anode with a Pt / Ir interlayer with electrodeposited Pt on top (FIG. 5A) and a sALD Pt coating (FIG. 5B). As seen in FIG. 5A, severe defects were visible both in the Pt / Ir interlayer and in the electrodeposited Pt layer.

[0114] Furthermore, cracks were visible in the interface between the Pt / Ir interlayer and the electrodeposited Pt layer. This indicated poor adhesion between the two coatings that resulted in coating delamination and reduced electrode lifetime. In contrast, the vertical cross-section of the sALD Pt layer in FIG. 5B with the Pt deposited directly on the Ti substrate showed no cracks or defects in the Pt coating. This indicated that the sALD Pt had increased adhesion compared to the electrodeposited Pt. It is noted that the elongated horizontal crack seen in FIG. 5B is from a sputtered Pt layer applied on top of the sALD coating to protect the sample during the SEM imaging process. The layer above the crack was therefore not a part of the sALD Pt coating and was not indicative of the performance of sALD for this example.Example 4

[0115] In this example, the coating of a Ti substrate with iridium (Ir) using spatial Atomic Layer Deposition (sALD) both with and without a protective interlayer is explored.

[0116] Samples for this example included Ti substrates prepared in a manner similar to Examples 1-6. Specifically, the samples included pretreated Ti substrates where one of the samples included a Ti / Ta interlayer that was applied using sputtering; the other sample was bare Ti. Both Ti substrates were dosed with the Ir precursor (EtCp)Ir(CHD) in a sALD device followed by oxidation of the deposited Ir using an N2 / O2 plasma. For the sample with the sputter applied Ti / Ta interlayer, the interlayer was estimated to be about 1.5 μm thick.

[0117] FIG. 6 illustrates a comparison of the oxygen evolution reaction (OED) activity, measured on an I-V curve, for both samples. As is shown in FIG. 6, the OER activity of sALD-Ir with the Ti / Ta interlayer is higher than the OER of the Ti substrate without the Ti / Ta interlayer, i.e., Ti with only a sALD Ir layer. FIG. 7 illustrates the durability of the two samples under galvanostatic conditions. In the embodiment shown, the end of lifetime was reached when the potential reached 10 V. As seen from FIG. 7, the sample with the sALD Ir over a Ti / Ta interlayer had almost three times the lifetime compared to the Ti substrate without the Ti / Ta interlayer, i.e., Ti with only a sALD Ir layer. Accordingly, it was determined that the activity and stability of catalytic layers for electrodes was improved with the presence of a Ti / Ta metallic interlayer.Example 5

[0118] In this example, the performance of electrodes used for polymer electrolyte membrane (PEM) water hydrolysis is explored.

[0119] PEM stack tests were performed in a single cell stack (EL10, Hydron Energy B. V) with an active area of 10cm2. A NAFION® 117 membrane with a cathode catalyst coated on one side (QuinTech Brennstoffzellen Technologie) was used. The loading of Pt on the single side catalyst coated membrane was 10 g / m2. Carbon paper (E35H, Freudenberg Performance Materials SE & Co. KG) was used as the cathode gas diffusion layer (GDL). Ti felt (2GDL10-0.25, Bekaert Fiber Technologies) with thickness of 0.25 mm was used as anode porous transport layer (PTL), with the anode catalyst coated on it. Prior to depositing the Ti / Ta interlayer, the substrate was etched for 10 minutes in 60° C. HCl. A mixed metal oxide of Ir and Ta was deposited on the anode PTL with an Ir loading of 20g / m2. When present, the interlayer consisted of an alloy of Ti / Ta between the anode PTL and MMO catalyst. Ultrapure water was used as the feed to the anode side of the stack. All measurements were done at 60° C. and 1 atm.

[0120] All measurements consisted of a preconditioning step (1.5 V for 30 min, 1.7 V for 30 min, 2 V for 2 h) followed by a beginning of life (BoL) polarization curve measured from 0.1 A / cm2 to 1.7 A / cm2. After the BoL polarization curve, the PEM stack was held at 1 A / cm2 for approximately 15 h to determine stability. FIG. 8 illustrates the stability of the two samples at a current density of 1 A / cm2. As seen from FIG. 8, the addition of the Ti / Ta interlayer, estimated to be about 1.5 μm thick, increased the stability of the PEM stack compared to the anode PTL and MMO catalyst without the Ti / Ta interlayer.Example 6

[0121] In this example, the elemental distribution in an electrode prepared using the methods disclosed herein, e.g., sALD catalytic layers applied to a sputtered interlayer, is explored.

[0122] A sample electrode was prepared using a Ti sheet substrate. A Ti / Ta interlayer was sputtered onto the surface of the Ti sheet. The interlayer was estimated to be about 200-300 nm thick. Following sputter applying of the interlayer, a layer of Ir was applied using sALD with the Ir precursor (EtCp)Ir(CHD). For spectroscopic analysis, the finished electrode sample was made into a cross-section using a focused ion beam.

[0123] FIG. 9 illustrates an electron map of the vertical cross-section of the electrode sample. The lighter colored area of FIG. 9 illustrate the sALD Ir layer and the Ti / Ta interlayer and the dark colored area illustrates the underlying Ti substrate. SEM / EDS elemental maps for the electrode sample are illustrated in FIG. 10A-10C showing the distribution of the elements in each layer of the sample. As illustrated in FIG. 10A, Ti is located primarily in the underlying electrode substrate with a minor fraction of Ti found in the interlayer. The Ir was found in both the uppermost region of the electrode and throughout the underlying substrate following sALD. As illustrated in FIG. 10C, the Ta was found almost exclusively in the interlayer as a relatively narrow band, with little to no penetration onto the underlying substrate.

[0124] The dark vertical line in FIG. 9 represents the axis for the relative distribution plot of Ir and Ta shown in FIG. 11. In FIG. 11, the data was fitted with a simple Gaussian curve to show the general trends. FIG. 11 indicated that the Ir was concentrated at the edge of the Ta interlayer. Though the Ir layer was around 20 nm thick, it was observed that the Ir had a significant spread of hundreds of nm into the underlying layers. This effect was attributed to the SEM / EDS imaging technique.

[0125] Having now described some illustrative embodiments of the disclosure, it should be apparent to those skilled in the art that the foregoing is merely illustrative and not limiting, having been presented by way of example only. Numerous modifications and other embodiments are within the scope of one of ordinary skill in the art and are contemplated as falling within the scope of the disclosure. In particular, although many of the examples presented herein involve specific combinations of method acts or system elements, it should be understood that those acts and those elements may be combined in other ways to accomplish the same objectives.

[0126] Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary and that actual parameters and / or configurations will depend on the specific application in which the systems and techniques of the present disclosure are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments of the disclosure. It is therefore to be understood that the embodiments described herein are presented by way of example only and that, within the scope of the appended claims and equivalents thereto; the present disclosure may be practiced otherwise than as specifically described.

[0127] Moreover, it should also be appreciated that the disclosure is directed to each feature, system, subsystem, or technique described herein and any combination of two or more features, systems, subsystems, or techniques described herein, if such features, systems, subsystems, and techniques are not mutually inconsistent, is considered to be within the scope of the disclosure as embodied in the claims. Further, acts, elements, and features discussed only in combination with one embodiment are not intended to be excluded from a similar role in other embodiments.

[0128] As used herein, the term “plurality” refers to two or more items or components. The terms “comprising,”“including,”“carrying,”“having,”“containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phases “consisting of” and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,”“second,”“third,” and the like in the claims to modify a claim element does not itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

Claims

1. An electrode comprising:an electrically conductive substrate;a first coating on a surface of the electrically conductive substrate, the first coating comprising one or more of platinum, iridium, titanium, and tantalum; anda second coating on a surface of the first coating, the second coating comprising one or more of tantalum, iridium, platinum, and ruthenium, the second coating having a substantially uniform composition and a thickness of less than about 100 nm.

2. (canceled)3. The electrode of claim 1, wherein the electrically conductive substrate comprises a metal or an alloy of metals selected from the group consisting of titanium, zirconium, niobium, and tantalum.

4. (canceled)5. The electrode of claim 1, wherein the first coating comprises a mixture of titanium and tantalum or any oxide thereof, an iridium-based mixed metal oxide, platinum, or a platinum oxide.6-7. (canceled)8. The electrode of claim 1, wherein the first coating comprises about 0.1 g / m2 to about 100 g / m2 platinum, iridium, titanium, or tantalum.

9. The electrode of claim 8, wherein the first coating comprises about 1 g / m2 to about 25 g / m2 platinum, iridium, titanium, or tantalum.

10. (canceled)11. The electrode of claim 1, wherein the first coating has a thickness of about 100 nm to about 2000 nm.

12. The electrode of claim 1, wherein the second coating comprises a mixture of iridium and tantalum.

13. The electrode of claim 12, wherein the molar ratio of iridium to tantalum in the second coating is about 2:1 to about 9:1.14-15. (canceled)16. The electrode of claim 1, wherein the second coating comprises about 0.1 g / m2 to about 100 g / m2 tantalum, about 0.1 g / m2 to about 100 g / m2 iridium, about 0.1 g / m2 to about 100 g / m2 ruthenium, and / or about 0.1 g / m2 to about 200 g / m2 platinum.

17. The electrode of claim 16, wherein the second coating comprises about 1 g / m2 to about 25 g / m2 tantalum, 1 g / m2 to about 25 g / m2 iridium, 1 g / m2 to about 25 g / m2 ruthenium, and / or 1 g / m2 to about 25 g / m2 platinum.

18. (canceled)19. The electrode of any one of claim 1, wherein the second coating has a thickness of about 10 nm to about 100 nm.

20. The electrode of claim 1, wherein the electrode provides for about a 300% improvement in durability compared to an electrode comprising a single layer coating consisting of a composition of the second coating, wherein durability is expressed as a time necessary to reach a certain potential at a working electrode under galvanostatic conditions.

21. The electrode of any one of claim 1, wherein the electrode provides for about a 50% greater activity than an electrode comprising a single layer coating consisting of a composition of the second coating, wherein activity comprises oxygen evolution reaction activity, measured on an I-V curve, wherein a steeper slope indicates a higher activity.

22. A method of preparing an electrode, comprising:preparing an electrically conductive substrate using one or more of a chemical bath, a laser treatment, an oxidative plasma treatment, or a reductive plasma treatment to remove contaminants and to develop a surface thereof;applying a first coating comprising an oxide of one or more of platinum, iridium, titanium, or tantalum to the developed surface of the prepared electrically conductive substrate, wherein the first coating is applied using physical application, chemical application, or magnetron sputtering; andapplying a second coating comprising an oxide of one or more of tantalum, iridium, platinum, or ruthenium to a surface of the first coating, the second coating having a substantially uniform composition and a thickness of less than about 100 nm, wherein the second coating is applied using atomic layer deposition.

23. (canceled)24. The method of claim 22, wherein the electrically conductive substrate is prepared using HCl etching and / or an oxidative plasma treatment followed by a reductive plasma treatment.

25. (canceled)26. The method of claim 22, further comprising, after applying the first coating, drying the first coating.

27. The method of claim 22, wherein the second coating is applied using spatial atomic layer deposition.

28. The method of claim 22, further comprising, after applying the first coating or the second coating, heating or plasma treating the first coating or the second coating, respectively.

29. The method of claim 28, wherein plasma treating the coating is performed using a nitrogen and / or oxygen plasma.30-32. (canceled)

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