Electrolytic cell system and electrode manufacturing method

Abstract

Electrolytic cell system and electrode manufacturing method. The electrolytic cell system may include a first vessel in communication with the electrolytic cell stack, a power source, electrodes, a separator, a membrane, and a second vessel in communication with the electrolytic cell stack. The electrodes may include a catalytic material and a microporous structure and / or a nanoporous structure. The electrode manufacturing method may include providing a substrate, contacting the substrate with an acidic solution, applying a current to the substrate, simultaneously depositing a support material and a base material, including a roughened material, on the substrate, and subjecting the roughened material to leaching.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 440,690, entitled "ELECTROLYSER SYSTEM AND METHOD OF ELECTRODE MANUFACTURE," filed January 23, 2023, the specification of which is incorporated herein by reference.

[0002] Embodiments of the present invention relate to electrolyzer systems that produce gaseous hydrogen using an anode, a cathode, and / or an ion exchange membrane separating the anode and cathode, and that are powered by renewable energy sources such as solar, wind, hydro, bioenergy, and geothermal energy. [Background technology]

[0003] Hydrogen is an important part of any discussion regarding sustainability and emission reduction across major energy sectors. In addition to being a feedstock and process gas for many industrial processes, hydrogen is emerging as a fuel alternative for transportation applications. Therefore, renewable hydrogen resources are needed to increase production capacity. Low-temperature water electrolysis is currently the most mature method for carbon-free hydrogen generation and is reaching a relevant scale that will impact the energy landscape. However, the cost of low-temperature water electrolysis still needs to be reduced to be economical with traditional sources for hydrogen production. Reductions in operating costs are enabled by the availability of low-cost sources of renewable energy, and there is potential for significant reductions in capital costs through material and manufacturing optimization. Summary of the Invention [Problem to be solved by the invention]

[0004] Challenges associated with hydrogen production through electrolyzer systems include the stability of the electrolyzer system and the high cost of electrode materials. Research efforts are underway aimed at improving the electrocatalytic activity of platinum group metals (PGM)-based catalysts. Other research efforts involve reducing PGM loading by developing non-PGM electrocatalysts or eliminating PGMs entirely. What is needed is a way to reduce the power load for hydrogen production and reduce the cost of electrode materials while maintaining or increasing their effectiveness. [Means for solving the problem]

[0005] The present invention relates to a system for electrolyzing a solution, the system comprising: a first vessel in communication with at least one electrolytic cell stack, the first vessel comprising at least one bipolar electrode comprising a bipolar plate, a porous transport layer, and a catalyst, the bipolar plate, porous transport layer, and catalyst being fused together into a single component; at least one separator; and a second vessel in communication with the at least one electrolytic cell stack. In another embodiment, the system further comprises a substrate. In another embodiment, the substrate supports the catalyst.

[0006] In another embodiment, the substrate comprises a conductive material. In another embodiment, the conductive material comprises iron. In another embodiment, the substrate comprises an alloy material. In another embodiment, the alloy material comprises a platinum group metal. In another embodiment, the substrate comprises a ceramic. In another embodiment, the bipolar plate is sintered.

[0007] The present invention also relates to a method of manufacturing a substrate, the method comprising providing a metal powder, contacting a polymer binder with the metal powder to form a metal binder mixture, and sintering the metal binder mixture. In another embodiment, the polymer binder comprises polyvinyl alcohol. In another embodiment, the polymer binder comprises polyethylene glycol. In another embodiment, the polymer binder comprises carrageenan. In another embodiment, the metal powder comprises nickel. In another embodiment, the metal powder comprises titanium. In another embodiment, the method further comprises contacting the metal binder mixture with a metal foam.

[0008] The present invention also relates to a substrate comprising a sintered porous structure, a conductive material, an alloy material, and a functional gradient. In another embodiment, the porous microstructure comprises a porosity of about 20% to about 95%. In another embodiment, the substrate comprises a porosity of about 2.5 g / cm. 3 ~approx. 3.4g / cm 3 In another embodiment, the conductive material comprises iron.

[0009] The objects, advantages, novel features and further scope of the present invention will be set forth in part in the following detailed description taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by the practice of the invention. The objects and advantages of the present invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. [Brief explanation of the drawings]

[0010] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. The drawings are as follows:

[0011] [Figure 1]FIG. 1 illustrates one embodiment of an electrolyzer system.

[0012] [Figure 2] FIG. 1 illustrates an embodiment of an electrolyzer stack.

[0013] [Figure 3] FIG. 1 illustrates an embodiment of a single cell ion exchange electrolyzer.

[0014] [Figure 4] FIG. 1 illustrates an embodiment of a bipolar plate.

[0015] [Figure 5A] FIG. 1 illustrates an embodiment of an electrolyzer cell with an applied magnetic field.

[0016] [Figure 5B] 5B is a graph showing the direction of current flow and magnetic field in the electrolyzer cell shown in FIG. 5A.

[0017] [Figure 6A] FIG. 1 illustrates one embodiment of a photoelectrochemical system layout.

[0018] [Figure 6B] FIG. 1 illustrates one embodiment of a photoelectrochemical system layout.

[0019] [Figure 7] FIG. 1 is a process flow diagram of one embodiment of electrode fabrication using sputtering or electroplating.

[0020] [Figure 8] FIG. 1 is a process flow diagram of one embodiment of electrode fabrication.

[0021] [Figure 9]1 is a series of graphs showing the initial performance and current density of a membrane electrode assembly ("MEA") having the novelty of the present invention compared to a commercially available MEA.

[0022] [Figure 10] 1 is a series of graphs showing the initial performance and long-term stability of MEAs having the novelty of the present invention compared to commercially available MEAs.

[0023] [Figure 11] 1 is a series of graphs illustrating the effect of selective etching and / or leaching of roughened material from the cathode and anode.

[0024] [Figure 12] 1 is a series of graphs illustrating the effect of heat treating cathodes and anodes.

[0025] [Figure 13] 1 is a series of photographs showing the microporous structure formed by roughening and / or leaching material from the cathode and / or anode.

[0026] [Figure 14] 1 is a graph showing the long-term stability of a nitrogen-assisted electrolyzer. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention is an electrolyzer system that may comprise bipolar plates, current collectors, separators, electrodes comprising catalytic materials and microporous structures, and an MEA / ion exchange membrane.

[0028] The term "metal" or "metals" is defined in this specification, claims, and drawings as a compound, mixture, or substance comprising a metal atom. The term "metal" or "metals" includes, but is not limited to, a metal hydroxide, a metal oxide, a metal salt, an elemental metal, a metal ion, a non-ionic metal, a mineral, or a combination thereof.

[0029] The terms "catalyst" or "catalytic material" shall be used interchangeably in this specification, claims, and drawings. The terms "separator" and "bipolar plate" shall be used interchangeably in this specification, claims, and drawings.

[0030] The term "leach" is defined herein and in the claims as a process used to liberate, extract, free, or remove one or more metals from a material.

[0031] The terms "micro-porous" or "micro-structure" are defined in this specification, claims, and drawings as a material in which at least a portion of the material comprises pores less than 1 millimeter in diameter.

[0032] The terms "nano-porous" or "nano-structure" are defined in this specification, claims, and drawings as materials in which at least a portion of the material comprises pores less than 1 micron in diameter.

[0033] The terms "tank" or "vessel" are used interchangeably in this specification, claims, and drawings and are defined as a holder, chamber, container, receptacle, and / or other object capable of containing a fluid. The terms are intended to encompass holders, chambers, containers, receptacles, and / or other objects of appropriate size or material. For example, they may include large, acid-resistant tanks or vessels for commercial-scale water electrolysis.

[0034] The term "platinum group metals" includes, but is not limited to, platinum, palladium, rhodium, ruthenium, iridium, osmium, or combinations thereof.

[0035] The electrolyzer system may split water into hydrogen and oxygen, or nitrogen compounds into hydrogen and nitrogen, at lower voltages than conventional electrolyzers. The electrolyzer system may have greater electrode or MEA efficiency and long-term stability than conventional electrolyzers.

[0036] The present electrolyzer system may achieve high cell current densities while reducing the need for PGMs. In particular, the present electrolyzer system may require less PGMs than conventional electrolyzers using PEM technology, and no PGMs than conventional electrolyzers using AEM and AE technology.

[0037] Electrolyzer systems using nitrogen-assisted hydrogen generation do not have the risk of explosion caused by mixing of O2 gas and H2 gas because there is no oxygen generation. The performance stability of electrolyzer systems using nitrogen-assisted hydrogen generation can be higher compared to conventional water splitting systems, especially in long-term operation. By replacing the anodic reaction at the nitrogen anode with oxygen, the electrolyzer system can be operated at lower or zero voltage, avoiding anode oxidation and corrosion due to the presence of oxygen, i.e., nitrogen is generated instead of oxygen. Electrolyzer systems using nitrogen-assisted hydrogen generation can have a higher range of stability, for example, at least 100 hours of continuous operation with performance changes, compared to electrolyzer systems that use water to generate hydrogen.

[0038] Referring now to the drawings, Figure 1 shows an electrolyzer system 10. A water tank 12 may provide a water flow 14 to a positive end 18 of an electrolyzer stack 16. The electrolyzer stack 16 may be powered by a power supply 20 connected to the positive end 18 and the negative end 22. Electrons may flow along a path 24 within the electrolyzer stack 16 to split water into molecular oxygen and molecular hydrogen. Oxygen may exit the electrolyzer stack 16 via an outlet 26, and hydrogen may exit the electrolyzer stack 16 via an outlet 28. The hydrogen may be collected in a hydrogen storage tank 30.

[0039] 2 shows the electrolyzer stack 16 with an exploded view of a single electrolyzer cell 42. The individual electrolyzer cells may be held together in the stack by connectors 32. The single electrolyzer cell 34 may include electrodes 38 disposed at least partially between separators and / or bipolar plates 36. A membrane 40 may be disposed at least partially between the electrodes 38. Hydrogen 27 and oxygen 25 may be produced in the separators and / or bipolar plates 36 and may exit the single electrolyzer cell 34 on either side of the single electrolyzer cell 34.

[0040] FIG. 3 shows a single-cell ion exchange electrolyzer 42. The membrane 40 may be at least partially disposed between gaskets 52. The membrane 40 may include an ion exchange membrane 56, an oxygen evolution reaction (OER) catalyst 58, and a hydrogen evolution reaction (HER) catalyst 60. The OER catalyst 58 and the HER catalyst 60 may include gas diffusion layers (GDLs). The ion exchange membrane 56 may be at least partially disposed between the OER catalyst 58 and the HER catalyst 60. The gaskets 52 may be at least partially disposed between flow field plates 50. The flow field plates 50 may be at least partially disposed between separators and / or bipolar plates 36. The separators and / or bipolar plates 36 may include end plates 49 and current collectors 48. The single-cell ion exchange electrolyzer 42 may include an anode cell 44. The anode cell 44 may include a separator and / or bipolar plate 36, a flow field plate 50, a gasket 52, and an OER catalyst 58. The single-cell ion exchange electrolyzer 42 may include a cathode cell 46. The cathode cell 46 may include a separator and / or bipolar plate 36, a flow field plate 50, a gasket 52, and an HER catalyst 60. Figure 4 shows one embodiment of a separator and / or bipolar plate with a serpentine channel pattern 62 that may be a component of a single-cell ion exchange electrolyzer 42.

[0041] 5A and 5B show an electrolyzer cell 64 with an applied magnetic field and graphs illustrating current flow and the magnetic field in the electrolyzer cell 64 with an applied magnetic field. The cell assembly 65 may be at least partially disposed between a south magnetic field end 66 and a north magnetic field end 68. The cell assembly 65 may include separators and / or bipolar plates 36, electrodes 38, and a membrane 40. Optionally, the electrodes 38 may be replaced with a porous transport later and / or the membrane 40 may be replaced with an MEA including a catalyst, a GDL, and the electrodes 38. A magnetic field 69 may be applied to the separators and / or bipolar plates 36 and / or the electrodes 38. The magnetic field may be applied parallel to the south magnetic field end 66 and the north magnetic field end 68, and the current may be applied perpendicular to the magnetic field. The current may flow across and / or through at least one of the components of the cell assembly 65.

[0042] 6A and 6B show electrode arrangements of photoelectrochemical system 70 and photoelectrochemical system 78. Photoelectrochemical system 70 includes a photocathode 74 disposed at least partially between a photoanode 72 and a solar panel 76. Photoelectrochemical system 78 includes a photoanode 72 disposed at least partially between the photocathode 74 and the solar panel 76. The solar panel 76 may convert solar radiation into electrical power and provide a voltage to the photoanode 72 and / or across the photocathode 74. Optionally, the photocathode 74 and / or photoanode 72 may generate electron current by directly receiving solar radiation.

[0043] FIG. 7 illustrates one embodiment of an electrode fabrication method using sputtering or electroplating. In a sputtering fabrication method 80, a substrate may be pretreated by a cleaning step 82. The cleaning step 82 may comprise degreasing and / or deoxidation. The substrate may then undergo electrochemical activation 84 by applying an electric current. The activated substrate may undergo drying 86 after sputtering 88 of a compound comprising a primary material and a support material. The support material may comprise a roughened material. The primary material and support material may undergo leaching 90. Optionally, the scarifying compound may undergo doping 92 to introduce a doping agent into the primary material. The substrate with the roughened compound may undergo a heat treatment 94.

[0044] In the electroplating method 96, the substrate may be pretreated by a cleaning step 82. The cleaning step 82 may comprise degreasing and / or deoxidation. The substrate may then undergo electrochemical activation 84 by applying an electric current. The activated substrate may undergo electroplating 98 of a compound comprising a primary material and a support material. The support material may comprise a roughened material. The primary material and support material may undergo leaching 90. Optionally, the roughened compound may undergo doping 92 to introduce a doping agent into the primary material. The substrate with the roughened compound may undergo a heat treatment 94.

[0045] FIG. 8 illustrates an electrode fabrication method 100. An electrode substrate may undergo a chemical and electrochemical pretreatment 102 followed by a first material deposition 104. The substrate may then undergo a first reagent rinse 108 and a second reagent rinse 110 followed by a first heat treatment 106. The water may comprise distilled water and / or purified water. The substrate may then undergo an acid rinse 122 followed by a third reagent rinse 114. The substrate may then undergo electrochemical activation 116 followed by a fourth reagent rinse 118. The substrate may then be dried 120 and undergo a second material deposition 122. The substrate with the deposited material may then undergo a selective etching and / or leaching 124 followed by a fifth reagent rinse 126 and a second heat treatment 128. The reagent in any of the rinse steps may comprise isopropyl alcohol, distilled water, purified water, acetone, ethanol, or a combination thereof.

[0046] Figure 9 shows a series of graphs comparing the initial performance and stability data of a commercially available MEA with an MEA of the present invention. The results demonstrate that, compared to the commercially available MEA, the MEA of the present invention can achieve the same current density with less applied voltage. The results also demonstrate that, compared to the commercially available MEA, the MEA of the present invention has improved long-term stability.

[0047] 10 shows a series of graphs illustrating the initial performance and current density of an electrode having the novelty of the present invention compared to a commercially available electrode. The graphs compare the initial performance and stability data of a commercially available MEA incorporating a cation exchange membrane with an MEA of the present invention incorporating a cation exchange membrane. The cation exchange membrane is disposed at least partially between the anode and cathode compartments of the MEA of the present invention and the commercially available MEA.

[0048] FIG. 11 illustrates the effect of selective etching and / or leaching on the roughening of material from the cathode and anode. The graph shows the performance of a cathode without selective etching or leaching and the performance of a cathode with selective etching or leaching. The cathode with selective etching or leaching retains more energy for a given voltage compared to a cathode without selective etching or leaching. The graph shows the performance of an anode without selective etching or leaching and the performance of an anode with selective etching or leaching. The anode with selective etching or leaching retains more energy for a given voltage compared to anode without selective etching or leaching.

[0049] Figure 12 shows the effect of heat treating the cathode and anode. The graph shows the performance of the cathode and anode without and with heat treatment. Heat treatment improves the performance of the cathode and anode.

[0050] 13 shows a microporous structure formed by roughening and / or leaching material from the cathode and / or anode. Image sequence 130 shows pores 134 interspersed in roughened and / or leached material 132. Image sequence 130 also shows catalytic material 138 bonded to substrate 136.

[0051] Figure 14 shows the current density of 10 mA cm in 1 M KOH and 0.2 M N2H4. -2 Figure 1 shows the long-term stability of a two-electrode hydrazine electrolyzer over 100 hours at room temperature. The voltage is stable over 100 hours. The voltage remains at approximately 0.45 V throughout the operation of the hydrazine electrolyzer system.

[0052] The electrolyzer system may include at least one electrolyzer stack. The electrolyzer stack may include at least one electrolysis cell. The electrolysis cell may include an anode cell and / or a cathode cell. The anode cell and / or the cathode cell may include a bipolar plate, a flow field plate, a gasket, an electrode, a catalyst, or a combination thereof. A membrane may be disposed between the anode cell and the cathode cell. The bipolar plate may include an end plate, a current collector, a flow channel, or a combination thereof, which may facilitate the conversing of gases dissolved in the solution into gases. The flow field plate may include a flow field.

[0053] The electrolyzer system may comprise a membrane. The membrane may comprise a proton-exchange membrane (PEM), an anion-exchange membrane (AEM), an alkaline electrolyzer (AE) stack, or a combination thereof. The PEM and / or AEM may comprise a PGM. The PEM and AEM may be ion-exchange membranes. The electrolyzer system may further comprise a cation-exchange membrane, including, but not limited to, Nafion 115, Nafion 117, Nafion 212, perfluorosulfonic acid membrane, polytetrafluoroethylene membrane, chlor-alkali membrane, carboxyl membrane, or a combination thereof. The electrolyzer may achieve high cell current density using electrodes comprising metal or mixed metal-metal oxide microstructures and / or nanostructures. The electrolyzer may comprise a cathode catalyst and / or an anode catalyst. The cathode catalyst and / or an anode catalyst may comprise a PGM. The magnetic field can be applied externally to an electrolyzer system, including, but not limited to, a PEM, an AEM, an AE stack, an electrode, a catalyst, or a combination thereof. The electrolyzer system can be a hydrogen electrolyzer system. The membrane has a capacitance of at least about 0.2 mg cm. -2 , about 0.2 mg cm -2 ~Approx. 3mg cm -2 , about 0.4 mg cm -2 ~Approx. 2.5mg cm-2 , about 0.6 mg cm -2 ~Approx. 2.0mg cm -2 , about 0.8 mg cm -2 ~Approx. 1.5mg cm -2 , about 1.0 mg cm -2 ~Approx. 1.2mg cm -2 , or approximately 3 mg cm -2 It may comprise:

[0054] The MEA may comprise an AEM. The MEA may comprise a binder. The binder may comprise an anionic binder, a cationic binder, or an ionomer binder, or a combination thereof. The binder may be at least partially disposed between the anode and the AEM. The binder may also be at least partially disposed between the cathode and the AEM. The AEM may comprise an anion exchange membrane and / or a cation exchange membrane. The binder may improve ionic conductivity between the AEM and the anode and / or cathode by at least about 10%, about 10% to about 40%, about 15% to about 35%, about 20% to about 30%, or about 40%. The binder may comprise an ionomer and may be anionic or cationic. The binder may be at least partially disposed between the AEM and the corresponding anode or cathode in one of the following orders: anode, first (anionic) binder, AEM, second (anionic) binder, cathode, anode, first (cationic) binder, AEM, second (cationic) binder, cathode; anode, a first (anionic) binder, an AEM, a second (cationic) binder, a cathode, or • Anode, first (cationic) binder, AEM, second (anionic) binder, cathode.

[0055] The membrane of the MEA may comprise a PEM. The PEM has a current of about 4 A cm -2 Less than 0.5A cm -2 ~Approx. 4A cm -2 , about 1A cm -2 ~Approx. 3.5A cm -2 , about 1.5A cm-2 ~Approx. 3A cm -2 , about 2A cm -2 ~Approx. 2.5A cm -2 , or approximately 4A·cm -2 The cationic binder may comprise an ionomer and may be prepared from an ionomer solution of at least about 5 wt. %, about 5 wt. % to about 20 wt. %, about 10 wt. % to about 15 wt. %, or about 20 wt. % ionomer. In conventional PEM electrolyzer technology, the anode catalyst and cathode catalyst comprise PGM. Platinum is primarily used to fabricate the cathode, and iridium and ruthenium are used to fabricate the anode. The amount of platinum group material used by conventional PEM electrolyzer technology is typically 1-3 mg / cm. 2 The electrolytic cell system of the present invention with a PEM can achieve a concentration of at least about 0.01 mg / cm without sacrificing performance. 2 , about 0.01mg / cm 2 ~about 0.1mg / cm 2 , approximately 0.02 mg / cm 2 ~about 0.09mg / cm 2 , about 0.03mg / cm 2 ~approximately 0.08 mg / cm 2 , approximately 0.04 mg / cm 2 ~about 0.07mg / cm 2 , about 0.05mg / cm 2 ~about 0.06mg / cm 2 , about 0.1mg / cm 2 The PEM may also include a cation membrane and / or a cation exchange membrane.

[0056] The electrolyzer system may comprise a photoelectrochemical ("PEC") system used for water splitting. The PEC system may comprise a transparent / semitransparent photoanode (PA), a transparent / semitransparent photocathode (PC), a solar cell (SC), or a combination thereof. The PEC system may enable the production of green hydrogen from sunlight and water with a high solar-to-hydrogen conversion efficiency, i.e., the yield of hydrogen gas is high compared to the amount of hydrogen produced by an electrolyzer without a solar panel and PEC system. The PEC system may comprise non-III-V compound materials, such as conductive metal oxides and perovskite materials.

[0057] The electrolyzer system may be equipped with solar panels as a power source. Solar panels can be integrated into the PEC system to generate green hydrogen directly from sunlight and water, improving solar-to-hydrogen (STH) efficiency.

[0058] The photoanode may comprise n-type semiconductors and / or perovskite materials, including, but not limited to, BiVO4, TiO2, WO3, SrTiO3, Fe2O3, ZnO, or combinations thereof. The n-type semiconductors and / or perovskite materials may be used to form heterostructures with bandgaps that may be transparent. Other compatible materials may also be co-deposited during the deposition of the anode material to form high-performance n-type semiconductors. ZnO and Ti, or ZnO, Ti, and W may be co-deposited to form high-performance mixed oxides. The photoanode may also be coated with nanoparticles of an anode catalyst, including, but not limited to, PGM-based or Ni-based alloys, to improve the overall performance of the photoanode.

[0059] The photocathode may comprise a p-type semiconductor and / or perovskite material, including, but not limited to, copper-based oxides, alloys of p-type metal oxides, or combinations thereof. The p-type semiconductor and / or perovskite material may form a heterostructure with a bandgap that may be transparent. The photocathode may be coated with nanoparticles of a cathode catalyst, including, but not limited to, PGM-based or Ni-based alloys, to improve the overall performance of the photocathode.

[0060] The photoelectrode, e.g., photoanode and / or photocathode, must meet a fill factor of greater than 50% and must meet a current density of 14 mA cm -2 Photoelectrodes can be fabricated to achieve photocurrent densities exceeding 1000 keV. The materials in the photoelectrode can be optimized to achieve a crystalline structure. The crystalline structure can require the formation of nanocrystals on the photoelectrode. The nanocrystals can be formed by adjusting the deposition of materials on the electrode, for example, by controlling the deposition time, deposition temperature, deposition pressure, by controlling the reactive gas, or a combination thereof. The interface between the nanocrystals and the electrode surface can also be optimized to integrate the nanocrystals into the photoelectrode. The interface can be optimized by controlling the deposition parameters of each material, for example, by controlling the deposition time, deposition temperature, deposition pressure, by controlling the reactive gas, deposition power, gas flow rate, or a combination thereof. Interface engineering can prevent changes in the surface morphology and shape of the nanocrystals.

[0061] The photoanode and photocathode can then be integrated together using sequential deposition. The integrated photoelectrode can then be directly integrated into a solar cell or solar panel using physical and / or chemical deposition. The integration of the photoelectrode with the solar cell or solar panel can be done by controlling the light absorption of each photoelectrode or solar component so as not to interfere with the performance of the remaining photoelectrodes or solar components. Light absorption can be controlled by adjusting the crystalline quality and thickness of the material by adjusting the deposition parameters.

[0062] The STH efficiency of a PEC system can depend on the short-circuit photocurrent density, the Faradaic efficiency for hydrogen generation, and the incident light power density. All of these parameters need to be measured under standard direct sunlight illumination conditions (AM 1.5G solar spectrum). STH efficiency can be measured according to Equation 1:

number

[0063] The STH efficiency is a function of the thermodynamic potential (V redox ) multiplied by the electrolysis current (IWE) and the Faraday efficiency of hydrogen evolution (ηF), then multiplied by two and then divided by the input optical power (Pin).

[0064] PEC systems can use non-III-V materials that can affect photocurrent density and hydrogen generation while achieving STH efficiencies up to 30%, which is approximately three times the STH efficiencies achieved with conventional PEC technology.

[0065] The electrolyzer system may include at least one electrolytic cell at least partially disposed between a pair of electromagnetic plates. The pair of electromagnetic plates may be electromagnetically disposed perpendicular to the flow of current in the stack of electrolytic cells. The electromagnetic plates may generate a quasi-uniform magnetic field. The electromagnetic plates may accelerate the collection of hydrogen gas. The acceleration of the hydrogen gas may be achieved by the cooperative effect of the quasi-uniform magnetic field and the flow of current through the electrolyzer stack. The charge carriers may comprise protons.

[0066] Electrolyzer systems can produce hydrogen from nitrogen compounds in solution (nitrogen-assisted hydrogen production). Nitrogen-assisted hydrogen production can occur in membrane electrolyzers (either PEM or AEM), alkaline electrolyzers with a diaphragm to separate N2 and H2 gases, electrolyzers without a membrane, or a combination thereof. Nitrogen-assisted hydrogen production can require contacting nitrogen compounds with an electrolyzer. Nitrogen and hydrogen can be produced according to Equation 2 or Equation 5, which are derived from the anodic half-reactions of Equation 3 and Equation 6, and the cathodic half-reactions of Equation 4 and Equation 7. N2H4 → N2 + 2H2E VS.SHE =-0.33V(2) Anode: N2H4+4OH - →N2+4H2O+4e - E VS.SHE =-1.16V (3) Cathode: 4H2O+4e - →2H2+4OH - E VS.SHE =-0.83V(4) CO(NH2)2+H2O→3H2+N2+CO2E VS.SHE =+0.37V(5) Anode: CO(NH2)2+6OH - →N2+CO2+5H2O+6e - E VS.SHE =-0.46V(6) Cathode: 6H2O+6e - →3H2+6OH - E VS.SHE =-0.83V(7)

[0067] The nitrogen compound may comprise hydrazine, urea, or any other reagent capable of decomposing into nitrogen upon dissolution in the electrolyte. Nitrogen-assisted hydrogen generation can generate nitrogen at the anode (e.g., the anode) instead of generating oxygen. Nitrogen generation can reduce the overall cell voltage and power required to operate the electrolyzer system. The surface properties of the electrodes of the electrolyzer system can be adjusted to shift the electrochemical potential of the electrodes. Electrolyzer systems that decompose nitrogen compounds to generate nitrogen and oxygen can be operated at an applied voltage of at least about 10 mV to about 1.5 V, about 50 mV to about 1.0 V, about 100 mV to about 0.8 V, about 0.2 V to about 0.6 V, or about 1.5 V. Electrolyzer systems using nitrogen-assisted hydrogen generation can operate without an applied voltage and / or generate electricity as a byproduct.

[0068] Electrolyzer systems using nitrogen-assisted hydrogen generation can include an electrolyte bath including, but not limited to, hydrazine, urea, any other reagent that can be decomposed to nitrogen when dissolved in the electrolyte, or combinations thereof; distilled water; alkali metal electrolytes including, but not limited to, KOH, NaOH, K2CO3, or combinations thereof; acidic electrolytes including, but not limited to, H2SO4, H2CO3, or combinations thereof; or combinations thereof. The KOH can be at a concentration of at least about 1.0 M, from about 1.0 M to about 5.0 M, from about 1.5 M to about 4.5 M, from about 2.0 M to about 4.0 M, from about 2.5 M to about 3.5 M, or about 5.0 M. Hydrazine, urea, any other reagent that can decompose to nitrogen when dissolved in the electrolyte, or a combination thereof, can be at a concentration of at least about 0.01 M, about 0.01 M to about 3.0 M, about 0.5 M to about 2.5 M, about 1.0 M to about 2.0 M, or about 3.0 M N2H4 or CO(NH2)2. The bath can be operated at temperatures above about 20°C, about 20°C to about 80°C, about 25°C to about 75°C, about 30°C to about 70°C, about 35°C to about 65°C, about 40°C to about 60°C, about 45°C to about 55°C, or about 80°C. The oxygen-evolving reaction is prevented by controlling the concentration of nitrogen compounds through a closed circulation bath and an automatic dosing system, thereby preventing the nitrogen-evolving reaction from dominating. The risk of explosion caused by the mixture of H2 and O2 is eliminated.

[0069] The electrolyzer system may include a power source. The power source may generate alternating current, direct current, pulsed current, or a combination thereof. The power source may generate electrical energy from renewable energy sources, including, but not limited to, solar radiation, thermal energy, tidal current, wind power, bioenergy, or a combination thereof. The power source may transmit power, e.g., electrical current, to the electrolyzer cells of the electrolyzer system. The electrical energy may be transmitted from the power source to the electrolyzer system by at least one wire.

[0070] The electrolytic cell system may be operated at a temperature of at least about 20° C., from about 20° C. to about 80° C., from about 30° C. to about 70° C., from about 40° C. to about 60° C., or about 80° C. The operating temperature may preferably be about 60° C.

[0071] The electrolytic cell system may include an electrolyte. The electrolyte may include an alkaline electrolyte. The alkaline electrolyte may include an alkali metal, including, but not limited to, lithium ("Li"), sodium ("Na"), potassium ("K"), rubidium ("Rb"), cesium ("Cs"), francium ("Fr"), or a combination thereof. The electrolyte may include, but is not limited to, KOH, K2CO3, NaOH, or a combination thereof. The electrolyte may have a concentration of at least about 0.1 M, between about 0.1 M and about 3 M, between about 0.5 M and about 2.5 M, between about 1.0 M and about 2.0 M, or about 3.0 M.

[0072] The MEA can be directly bonded to a pair of electrodes and / or at least partially disposed between the pair of electrodes. The pair of electrodes can include an anode and a cathode. The anode and cathode can include a GDL and a catalyst in communication with the GDL. The catalyst can be attached to the GDL by physical or chemical deposition. The GDL can include a porous layer. Optionally, the anode and / or cathode can be a GDL with a catalyst coated on the surface of the anode and / or cathode. The GDL can include conductive fabric, paper, foam, mesh, felt, or a combination thereof. The GDL can have a thickness of at least about 0.1 mm, about 0.1 mm to about 2 mm, about 0.2 mm to about 1.6 mm, about 0.4 mm to about 1.2 mm, about 0.6 mm to about 0.8 mm, or about 2 mm. The GDL can have a specific or variable porosity of at least about 10%, between about 10% and about 99%, between about 20% and about 97%, between about 30% and about 95%, between about 40% and about 90%, between about 50% and about 80%, between about 60% and about 70%, or about 99%.

[0073] Electrode (e.g., cathode and / or anode) catalysts can be selected from HER and / or OER volcanographs, depending on the desired current density of the electrolytic cell system. HER catalysts can include, but are not limited to, Mo, Nb, W, Co, Ni, Re, Rh, Pd, Pt, Ir, Au, Ag, Fe, Ti, Ta, Tl, Cu, Bi, Cd, Ga, or combinations thereof. OER catalysts can include, but are not limited to, Cr, Ru, Mn, Fe, Ir, Co, Rh, Ni, Pt, Cu, Pt, Ag, Zn, Au, NbOx, ReOx, VOx, CrOx, SnObx, MoOx, MnOx, PtOx, IrOx, RuOx, TiOx, NiOx, PbObx, CoOx, or combinations thereof. The HER and / or OER are determined by the electrolysis system, electrolysis cell, and / or electrodes providing at least about 0.5 A cm at a cell voltage of 1.8 V. -2 , about 0.5A cm -2 ~Approx. 2A cm -2 , about 0.75A cm -2 ~Approx. 1.75A cm -2 , about 1A cm -2 ~Approx. 1.5A cm -2 , or approximately 2 A·cm -2 The cathode catalyst and the anode catalyst may comprise a non-PGM selected from one of the following: ●(Ni 0.7±0.1 Fe 0.3±0.1 ) α X β Y γ , where α+β+γ=100% (α is ≧50%, and β and γ make up the remaining 50%, each ranging from 0 to 50%), and X and Y are selected from one of Cr, Co, Mo, W, O, S, P, and N; ●(Al 0.5±0.1 )((Ni 0.7±0.1 Fe 0.3±0.1 ) α X β Y γ ) 0.5±0.1, where α+β+γ=100% (α is ≧50%, and β and γ make up the remaining 50%, each ranging from 0 to 50%), X and Y are selected from one of Cr, Co, Mo, W, O, S, P, and N, and the catalyst is activated by leaching aluminum to form a porous structure, and ●(Al 0.5±0.1 )(Ni 0.7±0.1 Mo 0.3±0.1 ) 0.5±0.1 , where the catalyst was activated by leaching aluminum to form a porous structure, and the current density was 2 A × cm at a cell voltage of 1.8 V. -2 Greater than.

[0074] The cathode catalyst may comprise a PGM selected from the following: ●(Al 0.5±0.1 )(Mo 0.7±0.1 Pt 0.3±0.1 ) 0.5±0.1 , and ●Al 0.7±0.1 Pt 0.3±0.1 .

[0075] The anode catalyst may comprise a PGM activated by leaching aluminum to form a porous structure selected from: ●(Al 0.5±0.1 )(Ir x Ru y ) 0.5±0.1、 ●(Ni 0.7±0.1 Fe 0.3±0.1 ) α X β Y γ , where α+β+γ=100% (α is ≧50%, and β and γ make up the remaining 50%, each ranging from 0 to 50%), X and Y are an inner layer selected from one of Cr, Co, Mo, W, O, S, P, and N, and Al 0.7±0.1 (IrOx) 0.3±0.1 The outer layer of ●(Ni 0.7±0.1 Fe 0.3±0.1 ) α X β Y γ, where α+β+γ=100% (α is ≧50%, and β and γ make up the remaining 50%, each ranging from 0 to 50%), X and Y are an inner layer selected from one of Cr, Co, Mo, W, O, S, P, and N, and (Al 0.5±0.1 )(Ir x Ru y ) 0.5±0.1 the outer layer of ●(Ni 0.7±0.1 Fe 0.3±0.1 ) α Al β (where α+β+γ=100% (α is ≧50%, and β and γ make up the remaining 50%, each ranging from 0 to 50).

[0076] The bipolar plate may include gas and / or liquid flow channels. The gas and / or liquid flow channels may include channels. The channels may include, but are not limited to, serpentine channel patterns, row pin channel patterns, or parallel or straight channel patterns, or combinations thereof. The bipolar plate may include current collectors, electrolyte pressure and flow controllers, electrical resistance regulators, or combinations thereof. The channel pattern of the bipolar plate and surface engineering of the materials deposited on these plates may affect the electrolyte pressure, electrolyte flow, and / or electrical resistance of the bipolar plate. The channel pattern of the bipolar plate may have a defined depth, width, and curvature.

[0077] The channel pattern of the bipolar plate can facilitate liquid and / or gas management within the electrolysis. Optimizing the bipolar plate can prevent gas from becoming trapped within the electrolytic cell system and improve electrolyte flow within and gas release from the electrolytic cell system. Optimization of the bipolar plate can be achieved by modifying the gas and / or liquid flow channel patterns to prevent gas from becoming trapped within the bipolar plate and / or electrolytic cell system, and by coating the bipolar plate with conductive and / or corrosion-resistant materials to avoid oxidation and promote electrical conductivity. The bipolar plate can comprise nickel, stainless steel, titanium, carbon-based products, aluminum, plastic, acrylic, foam, or combinations thereof. The conductive and corrosion-resistant material can comprise alloys, including, but not limited to, gold, silver, copper, aluminum, nickel, iron, molybdenum, chromium, niobium, ruthenium, rhodium, palladium, osmium, iridium, platinum, zinc, bronze, brass, or combinations thereof.

[0078] The electrolytic cell system may include electrodes fabricated by sputtering or electroplating. The electrodes may be fabricated by first pretreating a substrate. The substrate may include, but is not limited to, nickel, chromium-iron, molybdenum, copper, titanium, steel, stainless steel, nickel-chromium alloy, nickel-iron alloy, nickel-molybdenum alloy, nickel-copper alloy, titanium alloy, felt, paper, foam, or a combination thereof. The substrate may be cleaned and / or degreased to remove oil, grease, and / or native oxides from the substrate. The substrate may be cleaned and / or degreased by ultrasonic cleaning (resistivity greater than 18 Ω×cm) and / or contact with NaOH, acetone, ethanol, methanol, isopropyl alcohol, distilled water, or a combination thereof. The substrate may be cleaned and / or degreased at least once for at least about 5 minutes, about 5 to about 30 minutes, about 10 to about 25 minutes, about 15 to about 20 minutes, or about 30 minutes. Native oxides may be removed from the surface of the substrate by contacting the substrate with an acid. The substrate may be immersed in an acidic solution, which may include, but is not limited to, hydrochloric acid, hydrofluoric acid, sulfuric acid, or a combination thereof.

[0079] Optionally, the substrate may be contacted with an etchant capable of at least partially removing native oxide from the substrate. The acid may be at a concentration of about 5% or greater, about 5% to about 50%, about 10% to about 45%, about 15% to about 40%, about 20% to about 35%, or about 25% to about 30% by weight (w / w) in solution. The acid may be at a temperature of at least about 50°C, about 50°C to about 80°C, about 55°C to about 75°C, about 60°C to about 70°C, or about 80°C.

[0080] The substrate may be electrochemically activated by applying a current to the substrate, the applied current density being at least about 40 mA / cm 2 , about 40mA / cm 2 ~Approx. 1000mA / cm 2 , about 80mA / cm 2 ~about 900mA / cm 2 , about 100mA / cm 2 ~about 800mA / cm 2, about 200mA / cm 2 ~about 700mA / cm 2 , about 300mA / cm 2 ~about 600mA / cm 2 , about 400mA / cm 2 ~about 500mA / cm 2 , or about 1000mA / cm 2 The substrate may be activated by an HCl soak followed by washing and / or rinsing with acetone and / or deionized water.

[0081] Powder metallurgy (PM) techniques can be used to produce substrates for electrodes in electrolytic cell stacks. The substrate can be a platform onto which a catalyst is applied. The substrate can be a conductive material, including, but not limited to, iron metal, alloys, or combinations thereof. The substrate can be electrically conductive and can comprise a conductive metal, including, but not limited to, nickel, titanium, stainless steel, or combinations thereof. The substrate can operate in the chemical environment created within the electrolytic cell stack. The substrate can include, but is not limited to, nickel, iron, molybdenum, cobalt, titanium, tantalum, graphite, aluminum, tungsten, copper, silver, gold, platinum group metals, or combinations thereof. Alloying metals can also be present to tailor the properties of the substrate. The alloying metals can include, but are not limited to, zinc, tin, lead, or combinations thereof. The substrate can comprise a ceramic component, a transition metal oxide, a catalytically active material, or combinations thereof. Catalytically active materials may include, but are not limited to, iridium, platinum, molybdenum, titanium, tungsten, cobalt, nickel, niobium, palladium, ruthenium, rhenium, tantalum, bismuth, strontium, lanthanum, vanadium, indium, gold, silver, iron, copper, magnesium, zinc, chromium, nitrides, or oxides, phosphides, and sulfides of the foregoing materials, or combinations thereof. Any combination of catalytically active materials may support the catalytic process.

[0082] Ceramic and / or metal powders can be combined by mixing or grinding the precursor powders together in either a dry or wet state. In the dry state, the powders can be blended with a solid lubricant and binder. In the wet state, the binder, lubricant, plasticizer, surfactant, or combination thereof can be combined with a suitable carrier fluid having a solids loading of up to 60% by volume to produce a slurry. The carrier fluid can include, but is not limited to, alcohol, ethanol, water, acetone, or combinations thereof. The carrier fluid can have a solids loading of at least about 10% by volume, about 10% to about 75% by volume, about 20% to about 60% by volume, about 30% to about 50% by volume, or about 75% by volume. The slurry may have a viscosity of at least about 50 mPa·S, about 50 mPa·S to about 4500 mPa·S, about 100 mPa·S to about 4250 mPa·S, about 150 mPa·S to about 4000 mPa·S, about 200 mPa·S to about 3750 mPa·S, about 300 mPa·S to about 3500 mPa·S, about 400 mPa·S to about 3250 mPa·S, about 500 mPa·S to about 3000 mPa·S, about 750 mPa·S to about 2500 mPa·S, about 1000 mPa·S to about 2250 mPa·S, about 1000 mPa·S to about 2000 mPa·S, about 1250 mPa·S to about 1750 mPa·S, or about 4500 mPa·S. The viscosity may depend on the fabrication technique. Mechanical alloying may also be used to produce alloy feedstocks by mechanically combining the above-mentioned metals. Other fabrication techniques may include, but are not limited to, spray drying, freeze drying, powder tumbling, spheronization methods, sieving, screen cutting, or combinations thereof. The fabrication technique may be followed by tablet compression into a "green" compact. Additional fabrication techniques may include, but are not limited to, gel casting, tape casting, extrusion of a substrate material, or combinations thereof.

[0083] Fabrication of the substrate can involve powder compaction, where the compacted sheet can have a thickness of at least about 75 μm, about 75 μm to about 2500 μm, about 100 μm to about 2000 μm, about 200 μm to about 1800 μm, about 400 μm to about 1600 μm, about 600 μm to about 1400 μm, about 800 μm to about 1200 μm, or about 2500 μm. The compacted sheet can comprise pressed and / or compressed powder agglomerates bound together by a polymer matrix. The pressed and / or compressed powder agglomerates form a green compact. The green compact can then be sintered using a binder burnout step followed by partial sintering to retain the porous structure left by the incomplete compaction process and the burned-out polymer binder. Another method can produce a tape or film using slurry extrusion or casting, which is then subjected to the binder burnout and sintering process. The thickness of the tape or film for this method can be at least about 1 μm, from about 1 μm to about 2000 μm, from about 10 μm to about 1800 μm, from about 50 μm to about 1600 μm, from about 75 μm to about 1400 μm, from about 100 μm to about 1200 μm, from about 200 μm to about 1000 μm, from about 300 μm to about 800 μm, from about 400 μm to about 700 μm, from about 500 μm to about 600 μm, or about 2000 μm. The tape or file can be single-layered or multi-layered.

[0084] The sintering process can be performed under vacuum or in the presence of an inert gas, including, but not limited to, argon, helium, or a combination thereof. The sintering process can also be performed in the presence of other gases, including, but not limited to, nitrogen, methane, hydrogen, sulfur-containing gases such as H2S and SO2, or a combination thereof. The sintering process can produce desired microstructures and functional gradients within the PM substrate to form a sintered porous structure. Functional gradients are regions of varying material properties throughout the material, and can include density variations, composition variations, and typically both throughout the depth of the substrate material. Sintering and PM fabrication can produce highly porous regions. Highly porous regions can have a porosity of at least about 20%, between about 20% and about 95%, between about 25% and about 90%, between about 30% and about 85%, between about 35% and about 80%, between about 40% and about 75%, between about 45% and about 70%, between about 50% and about 65%, or between about 55% and about 60%. The porous region may act as a substrate for a catalyst.

[0085] The contact resistance between the bipolar plate, the porous transport layer ("PTL"), and the catalyst can determine the performance of the electrolyzer stack. An integrated single unit of "bipolar electrode" can be created by fusing the bipolar plate, the PTL, and the catalyst to form a single-piece component, which can eliminate contact resistivity between the components of the electrolyzer stack. The bipolar plate can increase the efficiency and long-term stability of the electrolyzer stack. Compared to current technologies for anion exchange membrane electrolyzers or fuel cells and proton exchange membrane electrolyzers or fuel cells, there is a mechanical connection between the porous transport layer and the bipolar plate. Furthermore, the catalyst particles are loosely connected to each other via the ionomer, resulting in high contact resistance and partial catalyst deactivation, resulting in extremely low catalyst utilization.

[0086] Bipolar plates can increase mechanical contact between components of the electrolytic cell stack, increasing mass transport, activation, and ohmic resistance of the electrolytic cell stack. Increased mechanical contact can improve overpotential and prevent degradation of long-term stability by eliminating contact resistance. In our proposed technology, the bipolar plates and electrodes can be sintered together at high temperatures ranging from at least about 500°C, from about 500°C to about 1100°C, from about 600°C to about 1000°C, from about 700°C to about 900°C, or about 1100°C. Sintering can be performed in the presence of gases including, but not limited to, argon, nitrogen, hydrogen, oxygen, sulfur, phosphides, or combinations thereof. Sintering can also be performed under vacuum or in the presence of ambient air. Sintering the bipolar plates can allow the porous transport layer and catalyst to operate with improved efficiency. Sintering the bipolar plate may allow the porous transport layer and the electrodes and / or catalyst of the bipolar plate to be fused together as a single component and to operate as a single electrolyzer part.

[0087] Sputtering or electrodeposition can be used to apply the material to the substrate. If sputtering is used to apply the material, the substrate can be dried. Drying can include nitrogen drying. Optionally, drying can be performed in a vacuum oven at a temperature range of at least about 60°C, about 60°C to about 250°C, about 80°C to about 230°C, about 100°C to about 210°C, about 120°C to about 190°C, about 130°C to about 170°C, or about 250°C. The substrate can be completely dried. If electroplating is used to apply the material, the substrate can be rinsed with a solvent. The solvent can comprise distilled water and / or purified water.

[0088] A material may be deposited on the surface of the electrode substrate. The material may comprise a compound material. The compound material may be deposited on the surface of the substrate by physical deposition, including but not limited to sputtering, electron beam evaporation, or a combination thereof, or by chemical deposition, including but not limited to electroplating, electrochemical deposition, or a combination thereof. The compound material may comprise a primary material and a support material. The primary material may comprise a catalyst. The catalyst may include, but is not limited to, Ir, Pt, Ru, Re, Pd, Ni, Fe, Mo, Cr, W, Ti, Co, alloys of Ir, Pt, Ru, Re, Pd, Ni, Fe, Mo, Cr, W, Ti, Co, or combinations thereof. The compound material may include, but is not limited to, NiPt, NiIr, NiRu, PtIr, PtRu, IrRu, IrW, IrTi, IrPd, or combinations thereof. The support material may comprise a surface roughening material and a dopant.

[0089] The roughened material may include, but is not limited to, Li, Ca, Na, Al, Mg, Zn, or a combination thereof. The roughened material may have a lower electrochemical potential compared to the main catalyst. The main material and the support material may be simultaneously deposited on the substrate. The amount of the main material and the support material deposited on the substrate may be at least 25% of the weight of the substrate. The roughened material may later be leached from the compound material by selective etching. An etchant or etching method may be used to selectively etch and / or leach the roughened material. Negligible etching and / or etching of the main material may occur during the leaching and / or selective etching process. The main material and the roughened material may be simultaneously deposited using either physical deposition and / or chemical deposition methods.

[0090] When using a physical deposition method, simultaneous deposition of the primary material and the roughening material can be achieved by using a compound target and / or compound target precursor of the material, or multiple targets and / or multiple target precursors of the material. The compound and / or multiple targets can depend on the physical deposition method. The precursor can be an atom in the compound and / or multiple targets, such as Pt, Ni, etc. By selecting an appropriate target or precursor, it can be possible to deposit, i.e., bond, the compound material onto the substrate. For example, when depositing the compound material by a sputtering method, a sputtering target can be used. The sputtering target can be a single material, including but not limited to Pt, Ni, or a combination thereof, and / or a combination of materials, including but not limited to NiPt, NiMo, NiPtIr, or a combination thereof. The target or compound target can be specific to the method. For example, when electron beam evaporation is used to deposit the compound material on the substrate, a precursor can be used instead of the compound or multiple targets. A mixed salt compound or salt of the compound material can be used to apply the compound material to the substrate using a chemical deposition method. The salts may include, but are not limited to, NiCl2·6H2O, FeCl2·4H2O, CoCl2·6H2O, (NH4)2MoO4, ZnCl2, T / H2PtCl6, CoCl2·6H2O, Ti / IrCl4·H2O, ZnCl2, or combinations thereof. When applying compound materials using electrochemical deposition, a pulsed current wave may be used. The pulsed wave may be t on The pulse wave may be at least about 50 μs, about 50 μs to about 5000 μs, about 100 μs to about 4500 μs, about 200 μs to about 4000 μs, about 300 μs to about 3500 μs, about 400 μs to about 3000 μs, about 500 μs to about 2500 μs, about 600 μs to about 2000 μs, about 700 μs to about 1500 μs, about 800 μs to about 1000 μs, or about 5000 μs. offThe time may be at least about 10 μs, about 10 μs to about 1000 μs, about 100 μs to about 900 μs, about 200 μs to about 800 μs, about 300 μs to about 700 μs, about 400 μs to about 600 μs, or about 1000 μs. Each compound material can be deposited separately and simultaneously to reach a target composition, i.e., simultaneous codeposition of the primary material and the supporting material onto the substrate. Simultaneous deposition allows for the formation of alloys and electrodes using up to 10 times less PGM-based material while exhibiting a higher degree of catalytic activity compared to conventional electrodes. The catalytic activity of the electrode is related to the surface of the active area. Leaching and / or selectively etching the roughened material creates a microporous and / or nanoporous structure within the electrode. The leached and / or selectively etched roughened material leaves pores within the compound material. The formation of the microporous and / or nanoporous structure increases the exposed surface area and / or active area of ​​the catalytic material. Increasing the surface area increases the catalytic activity of the electrode and reduces the amount of catalyst material required to fabricate the electrode. The active area can be increased by at least about 30%, about 30% to about 150%, about 40% to about 125%, about 50% to about 100%, about 60% to about 75%, or about 150%. The surface area of ​​the catalyst can be increased by at least about 10%, about 10% to about 75%, about 20% to about 70%, about 30% to about 60%, about 40% to about 50%, or about 75%.

[0091] By leaching and / or selectively etching the roughened material, micropores and / or nanopores can be formed in the compound material. The porous compound material can form the microporous and / or nanoporous structure of the electrode. The pore diameter of the nanoporous structure can be on the order of the width of the leached and / or selectively etched atoms, so that the pore diameter is wide enough to accommodate the leached and / or selectively etched atoms. For example, in a compound material comprising NiPt, Ni atoms will be leached and / or selectively etched from the NiPt compound to form a nanoporous structure comprising nanopores. The nanopores have a diameter sufficient to accommodate the Ni atoms.

[0092] The support material may comprise a doping agent, including, but not limited to, nitrogen, phosphorus, sulfur, boron, molybdenum, iron, chromium, cobalt, copper, or a combination thereof. The support material may comprise a doping compound, including, but not limited to, oxynitrides, nitrogen and sulfur compounds, nitrogen and phosphorus compounds, nitrogen and boron compounds, nitrogen and molybdenum compounds, nitrogen and iron compounds, or a combination thereof. Doping may be introduced into the main compound as a trace impurity to alter the surface properties of the electrode, including, but not limited to, the electrical properties or electrochemical potential. The doping agent may be present in trace amounts, i.e., less than 5%, in the main material. The doping agent may have a different atomic size and composition compared to the main compound, which is why it is called an impurity. Doping can occur during or after deposition of the compound material. Depending on the doping agent and its concentration, the doped material may have a cell potential lower than the theoretical minimum, ranging from 1.23 V to less than 0 V. Lowering the cell potential allows for the power applied to the cell to be reduced, thereby improving the overall efficiency of the electrolytic cell. The doping agent may improve the efficiency of the electrolytic cell system by at least about 10%, between about 10% and about 80%, between about 20% and about 70%, between about 30% and about 60%, between about 40% and about 50%, or about 80%.

[0093] Electrode surface properties can be tailored to achieve the required minimum potential and / or maximum efficiency by applying doping agents to the electrode. Doping agents can be added to the electrode by codeposition within the sputtered compound material, by using reactive gases during sputtering, by electrochemical and / or thermochemical addition after leaching and / or selective etching, or a combination thereof. In the codeposition method, the doping agent can be simultaneously deposited on the electrode along with other components of the compound material. The doping agent can comprise less than 10% of the compound material. In the reactive gas method, the ratio of nitrogen gas to argon gas can be less than about 30% to diffuse the doping agent, e.g., nitrogen, into the electrode simultaneously with the deposition of the main material. In electrochemical doping, doping agents, which may include, but are not limited to, N, P, S, and / or B, can be dissolved / dispersed in the electrolyte solution. The doping agent can be incorporated into the electrode and / or compound material by applying an electric potential to the electrolyte solution. The potential can be at least about 50 mV, about 50 mV to about 1500 mV, about 100 mV to about 1300 mV, about 200 mV to about 1100 mV, about 300 mV to about 900 mV, about 500 mV to about 700 mV, or about 1500 mV. In thermochemical doping, the compound material and doping agent can be placed in an inert gas-filled furnace, e.g., under an argon atmosphere. The doping agent can be implemented, diffused, and / or added to the compound material by increasing the temperature. The temperature can be increased to at least about 250°C, about 250°C to 900°C, about 300°C to 800°C, about 400°C to 700°C, about 500°C to 600°C, or about 900°C to dope the compound material with the doping agent. For all methods, the doped electrodes may be treated with a reagent, including but not limited to potassium hydroxide (KOH), potassium sodium tartrate tetrahydrate, or a combination thereof, followed by deionized water washing, nitrogen drying, oven drying, or a combination thereof, to form microporous and / or nanoporous structures. Additionally, for all methods, doping agents may be embedded, doped, and / or added to the compound material support material.

[0094] Various types of etching methods can be used to leach the roughened material, including but not limited to physical etching, including but not limited to reactive ion etching (RIE) and inductively coupled plasma etching, or chemical / electrochemical etching. Etching requires contacting the roughened material with a substance to remove it. One or more gases can be used as the etchant in physical etching. Reagents can be used in chemical / electrochemical etching. Electrodes can be etched by immersion in a bath containing a chemical / electrochemical etchant. The bath composition, operating temperature, time, and applied current can vary depending on the material selected for etching.

[0095] Baths for chemical / electrochemical etching may contain basic or acidic solutions, including, but not limited to, KOH, NaOH, HCl, H2SO4, or combinations thereof. The baths may also contain additives, including, but not limited to, buffers, hydrazine, antiscalants, etch accelerators, or combinations thereof. Buffers may include, but are not limited to, boric acid, borates, or combinations thereof, and may be used to maintain bath pH. Hydrazine may be used to prevent oxidation in baths with low pH values. Antiscalants, including, but not limited to, polyphosphates, may prevent salt deposition on the electrode during etching. Etch accelerators, including, but not limited to, sodium potassium tartrate tetrahydrate, may promote etching in alkaline environments. The baths may be operated at temperatures of at least about 25°C, from about 25°C to about 85°C, from about 30°C to about 80°C, from about 35°C to about 75°C, from about 40°C to about 70°C, from about 45°C to about 65°C, from about 50°C to about 60°C, or about 85°C. An electric current may be applied to the bath. The electric current may comprise a direct current, an alternating current, a pulsed current, or a combination thereof. The applied direct current may be at least about 25 mA / cm 2 , about 25mA / Cm 2 ~About 1000mA / Cm 2 , about 50mA / Cm2 ~about 900mA / Cm 2 , about 100mA / Cm 2 ~about 800mA / Cm 2 , about 200mA / Cm 2 ~about 700mA / Cm 2 , about 300mA / Cm 2 ~about 600mA / Cm 2 , about 400mA / Cm 2 ~about 500mA / Cm 2 , or approximately 1000mA / Cm 2 It could be.

[0096] The electrolytic cell system may include at least one electrode. The electrode may include an anode and / or a cathode. The electrode may be heat treated to improve performance. A vacuum heat treatment may be applied to the electrode. The vacuum heat treatment may be performed at a temperature of at least about 300°C, about 300°C to about 1000°C, about 400°C to about 900°C, about 500°C to about 800°C, about 600°C to about 700°C, or about 1000°C. The vacuum heat treatment may be performed for at least about 30 minutes, about 30 minutes to about 4 hours, about 1 hour to about 3.5 hours, about 1.5 hours to about 3 hours, about 2 hours to about 2.5 hours, or about 4 hours. The heat treatment may include increasing the temperature of the electrode, maintaining the temperature of the electrode, and decreasing the temperature of the electrode. The electrode temperature can be increased and decreased at a rate of at least about 5° C. / min, about 5° C. / min to about 20° C. / min, about 10° C. / min to about 15° C. / min, or about 20° C. / min.

[0097] The actual cell voltage of the electrolyzer system can be less than about 100 mV, compared to the theoretical minimum voltage of 1230 mV for water splitting at ambient temperature. The microporous and / or nanoporous structure of the electrode catalyst composition can reduce the cell voltage for water splitting to 0 mV, i.e., the electrolyzer system can become a self-sustaining electrolyzer and operate without an applied voltage. The use of doping agents, including but not limited to B and N, can shift the cathode potential to more positive values ​​and the anode potential to more negative values. The hydrogen production reaction can occur spontaneously without the need for any external power. The voltage for hydrogen reduction is much more positive than for hydrazine or urea oxidation at low pH values ​​on the cathode side of the electrolysis cell and high pH values ​​on the anode side of the electrolysis cell. The low pH value can be at least about 0, about 0 to about 5.5, about 2.5 to about 5, about 2.5 to about 4.5, about 3 to about 4, or about 5.5. The high pH value can be at least about 8, about 8 to about 14, about 9 to about 13, about 10 to about 12, or about 14. Hydrogen production then becomes thermodynamically favorable and occurs spontaneously as long as the salt concentrations on both sides are maintained. Thus, the nitrogen-assisted hydrogen electrolyzer can function autonomously to produce gaseous hydrogen and can also generate electricity. Approximately 1 A cm -2 High electrolytic cell current densities can result from the incorporation of metal or mixed metal-metal oxide nanoparticles into the electrodes.

[0098] The electrolytic cell system may include an anode cell and / or a cathode cell. The overall potential of the anode cell is about 10 mA cm. -2 The overall potential of the cathode cell can be less than about 250 mV, between about 250 mV and about 0 mV, between about 225 mV and about 10 mV, between about 200 mV and about 50 mV, between about 150 mV and about 100 mV, or about 250 mV at a current density of 10 mA cm. -2 At a current density of 100 mV, the voltage may be less than about 100 mV, about 0 mV to about 100 mV, about 5 mV to about 99 mV, about 10 mV to about 97 mV, about 15 mV to about 95 mV, about 20 mV to about 90 mV, about 30 mV to about 80 mV, about 40 mV to about 70 mV, about 50 mV to about 60 mV, or about 100 mV.

[0099] The cathode and anode can have the same material composition, i.e., function as a bifunctional electrode, or they can have different material compositions, e.g., function as separate electrodes. Bifunctional electrodes can have improved stability compared to separate electrodes because there is no difference in electrode composition, reducing or avoiding the risk of galvanic coupling and subsequent electrode corrosion and degradation. A Pt electrode with a cell volage of less than 100 mV can serve as a performance benchmark for both the anode and cathode.

[0100] The microstructured and / or nanostructured foams may comprise microstructured and / or nanostructured catalysts comprising metal or mixed metal-metal oxide nanoparticles. The metal or mixed metal-metal oxide may be applied to the microstructured and / or nanostructured foams using physical or chemical deposition methods, including, but not limited to, magnetron sputtering, plasma coating, electrolytic coating, or combinations thereof. The metal may comprise, but is not limited to, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt, Au, or combinations thereof. The metal oxide may be an oxide made from the above metals. [Industrial Applicability]

[0101] The present invention is further illustrated by the following non-limiting examples.

[0102] Example 1 The deposition of the compound material onto the substrate was performed by sputtering. After cleaning, the substrate was placed in a sputtering chamber (various models, such as DC, RF, or magnetron, were successfully tested) and heated for approximately 10 min. -6 The base pressure of 100 Torr (high vacuum) was reached. The main catalyst and roughening material was IrO x , NiN, NiO xN) in an argon atmosphere or an argon / oxygen / nitrogen atmosphere at a working pressure of approximately 3-9 mTorr, with a sputtering power ranging from 25-500 W and a gas flow rate ranging from 1-100 standard cubic centimeters.

[0103] Example 2 Deposition of the compound materials onto the substrate was performed by electrochemical deposition. There were several different methods. In one aspect, the electrochemical method was performed by using a pulse electrodeposition method or by forming a core-shell structure (roughened material as the core and the main catalyst as the shell). The temperature of the bath used in the electrochemical method was maintained using a constant temperature thermostat. Solutions were freshly prepared using deionized water and Anala® grade chemicals. Tables 1 and 2 show examples of solutions and salts used for electrochemical deposition. Table 1. AEM electrode bath composition [Table 1] Table 2: PEM electrode bath composition [Table 2]

[0104] Example 3 Electrodeposition of materials was performed using potentiostatic direct and pulsed current. The current value and time depended on the coating thickness and morphology and the targeted particle size range. Electroplating times ranged from 15 minutes to 1 hour. The applied current was 75 mA / cm. 2 ~500mA / cm 2 The pulse method was in the range of t on = 50μs~5000μs, t off A square wave of 10 μs to 1000 μs was used.

[0105] Example 4 Post-processing of the compound material deposited on the substrate was performed by leaching and doping. The leaching of the roughened material from the compound material resulted in the formation of a microstructure of catalytic material. This process was achieved by selective etching, which etches only specific materials with negligible effect on other materials in the system.

[0106] Example 5 Nickel substrates were prepared by ball milling nickel powder with ethanol, adding two polyvinyl alcohol (PVA) polymers, one low and one high molecular weight, and a surfactant, such as sodium hexametaphosphate. The slip was spray-dried to form spherical granular powders, sieved to a particle size of 20 μm to 200 μm, and punched at 200 N / mm using a punch and die. 2 The compact was uniaxially compressed to a pressure of 2.8 g / cm. The compact was removed from the die, placed on a sintering tray, and sintered at 700°C for 2 hours. 3 ~3.4g / cm 3 The resulting porous microstructure had a density of 1000 Å. The catalyst material was mixed into a thick, easily spreadable slurry, applied to the surface of the sintered substrate, and re-sintered to produce a multilayer structure. The thickness of the catalyst layer ranged from 1 μm to 150 μm, and multiple layers were optionally applied.

[0107] Example 6 Metal substrates were prepared. Metal powders were ground in a suitable solvent, glycerol trioleate, and polyethylene glycols of various molecular weights, for 100s. -1 Slurries were prepared at shear rates ranging from 1 Pa·s to 4 Pa·s. The slurries were cast onto nickel foam using a doctor blade technique and formed into films ranging in thickness from 1 μm to 2000 μm. The films were dried in situ, then removed, subjected to a binder burnout step (dewaxing), and sintered between 500°C and 1100°C to produce porous multilayer structures.

[0108] Example 7 Nickel-titanium substrates were prepared. A nickel-titanium powder mixture was milled and commercial carrageenan was added. Carrageenan is a large-molecule polysaccharide used to form a gel network. The milled mixture was heated to 85–95°C while mixing the additives. Above 60°C, the slurry remained liquid; below this temperature, the slurry gelled over time. The slurry was spread onto nickel foam (or a similar porous structure) and allowed to cool and solidify. After drying under vacuum for several hours, the parts were sintered at 500–1100°C.

[0109] The foregoing examples can be repeated with similar success by substituting the general or specifically described components and / or operating conditions of embodiments of the invention for those used in the foregoing examples.

[0110] It should be noted that in this specification and claims, "about" or "approximately" means within twenty percent (20%) of a given amount or value.

[0111] Embodiments of the present invention may include any combination of features disclosed herein independently of each other. Although the present invention has been described in detail with particular reference to the disclosed embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be apparent to those skilled in the art, and it is intended that all such variations and equivalents be covered in the appended claims. The entire disclosures of all references, applications, patents, and publications cited above are incorporated herein by reference. Unless specifically stated above as "essential," none of the various components or their interrelationships are essential to the operation of the present invention. Rather, desired results may be achieved by substituting the various components and / or rearranging their relationships with one another.

Claims

1. 1. A system for electrolyzing a solution, comprising: a first vessel in communication with the at least one electrolytic cell stack, Bipolar plates and a porous transport layer; Catalyst and At least one bipolar electrode comprising: At least one bipolar electrode, wherein the bipolar plate, the porous transport layer, and the catalyst are fused together into a single component. a first container comprising: at least one separator; a second vessel in communication with the at least one electrolytic cell stack; A system comprising:

2. The system of claim 1 further comprising a substrate.

3. The system of claim 2 , wherein the substrate supports the catalyst.

4. The system of claim 2 , wherein the substrate comprises a conductive material.

5. The system of claim 4 , wherein the conductive material comprises iron.

6. The system of claim 2 , wherein the substrate comprises an alloy material.

7. The system of claim 6 , wherein the alloy material comprises a platinum group metal.

8. The system of claim 2 , wherein the substrate comprises a ceramic.

9. The system of claim 1 , wherein the bipolar plate is sintered.

10. 1. A method of manufacturing a substrate, comprising: Providing a metal powder; contacting a polymeric binder with the metal powder to form a metal binder mixture; sintering the metal binder mixture; and A method comprising:

11. The method of claim 10 , wherein the polymer binder comprises polyvinyl alcohol.

12. The method of claim 10 , wherein the polymer binder comprises polyethylene glycol.

13. The method of claim 10, wherein the polymeric binder comprises carrageenan.

14. The method of claim 10 , wherein the metal powder comprises nickel.

15. The method of claim 10 , wherein the metal powder comprises titanium.

16. The method of claim 10 further comprising contacting the metal bond mixture with a metal foam.

17. a sintered porous structure; a conductive material; an alloy material; Functional gradient and A substrate comprising:

18. The substrate of claim 17 , wherein the porous microstructure comprises a porosity of about 20% to about 95%.

19. The substrate of claim 17, wherein the substrate comprises a density of about 2.5 g / cm 3 to about 3.4 g / cm 3 .

20. The substrate of claim 17 , wherein the conductive material comprises iron.

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