Conductive corrosion-resistant magnesium-titanium oxide material

Abstract

The invention relates to electrically conductive corrosion resistant magnesium titanium oxide materials. A fuel cell catalyst system comprises a catalyst and a catalyst support material that incorporates the catalyst and comprises a corrosion resistant electrically conductive material having oxygen vacancies of formula (I): wherein δ is any number from 0 to 3, optionally including a fractional part, representing oxygen vacancies, the material having an electrical conductivity of about 2-10 S / m at room temperature in ambient environment.

Description

Technical Field

[0001] This invention relates to corrosion-resistant conductive magnesium titanium oxide materials with oxygen vacancies. Background Technology

[0002] Metals have been widely used materials for thousands of years. Various methods have been developed to protect metals and prevent them from corroding or disintegrating into oxides, hydroxides, sulfates, and other salts. Metals are particularly susceptible to corrosion in some industrial applications due to the corrosive working environments. Non-limiting examples include metal components of fuel cells, such as bipolar plates (BPPs) or catalyst support materials for fuel cells. Furthermore, some components, such as BPPs, not only need to be chemically inert to resist degradation in the highly corrosive environment of fuel cells, but also need to be conductive to facilitate electron transfer in the oxygen reduction reaction of the fuel cell. Finding materials that meet both of these requirements has been a challenge. Summary of the Invention

[0003] According to one embodiment, a fuel cell catalyst system is disclosed. The fuel cell catalyst system comprises a catalyst and a catalyst support material, wherein the catalyst support material is incorporated with the catalyst and comprises a corrosion-resistant conductive material having oxygen vacancies according to formula (I):

[0004]

[0005] Where δ is any number from 0 to 3 representing oxygen vacancies, optionally including a decimal part. The material can have a conductivity of approximately 2-10 S / m at room temperature in the ambient environment. The static corrosion current density of the bipolar plate can be less than approximately 1 μA cm⁻¹ at pH 2 and a temperature range of approximately 0-80°C. -2 The Mg / Ti ratio of the material can be a number in the range of 0.3-0.6. δ may include a decimal part. The material may be non-stoichiometric. The catalyst may be a redox catalyst. The catalyst may contain at least some Pt(100) surface facets. The catalyst may form at least one island on the catalyst support material.

[0006] In an alternative embodiment, a corrosion-resistant conductive material is disclosed. The corrosion-resistant conductive material may comprise a metal oxide crystalline structure having oxygen vacancies of formula (I):

[0007]

[0008] Where δ is any number from 0 to 3, optionally including a decimal part and representing oxygen vacancies. The material may have a nominal chemical composition of approximately 33 mol% MgO and 66 mol% TiO and TiO2 mixture. The Mg / Ti ratio may be a number in the range of 0.3-0.6. δ may include a decimal part. The static corrosion current density of the bipolar plate at pH 2 at a temperature of approximately 0-80°C is less than approximately 1 μA cm⁻¹. -2 The material may be a fuel cell catalyst support material. The material may be non-stoichiometric.

[0009] In yet another embodiment, a catalyst support is disclosed. The catalyst support may comprise a corrosion-resistant, conductive crystalline material having oxygen vacancies according to formula (I):

[0010]

[0011] Where δ is any number from 0 to 3 representing oxygen vacancies, optionally including a decimal part. The crystalline material can have an electrical conductivity of about 2-10 S / m at room temperature in the surrounding environment. The catalyst can be a cathode fuel cell catalyst. The static corrosion current density of the bipolar plate can be less than about 1 μA cm⁻¹ at a temperature of about 0-80°C at pH 2. -2 The Mg / Ti ratio of the material can be a number in the range of 0.3-0.6. The material can have an activation energy of about 0.13 eV in a temperature range of 25℃-80℃. δ may include a decimal part. Attached Figure Description

[0012] Figure 1 A schematic composition of a proton exchange membrane fuel cell including bipolar plates according to one or more embodiments is depicted;

[0013] Figure 2 A perspective view showing a non-limiting example of a bipolar plate having a body portion and a surface portion comprising a corrosion-resistant and conductive material according to one or more embodiments;

[0014] Figure 3 Non-limiting examples of synthetic pellet samples of the disclosed material are shown;

[0015] Figure 4A and 4B The structures of MgTi2O5, which exhibit insulating behavior, and MgTi2O, which exhibit conductive behavior, are shown respectively. 4.92 The density of states (DOS);

[0016] Figures 5A to 5E It shows (110)MgTi2O5, (110)MgTi2O 5-δThe chemical structures of (101)TiO2 (anatase), (110)TiO2 (rutile) and (001)TiO;

[0017] Figure 6 MgTi2O was shown 5-δ Arrhenius curve of conductivity from 25℃ to 80℃;

[0018] Figure 7 The original, freshly synthesized MgTi2O was shown after annealing in air. 5-δ MgTi2O 5-δ And TiO2 of Ti2 p X-ray photoelectron spectroscopy (XPS) spectrum;

[0019] Figure 8 It is freshly synthesized MgTi2O 5-δ X-ray diffraction (XRD) patterns of MgTi2O5 vs. MgTi2O5;

[0020] Figures 9A to 9C show MgTi2O synthesized immediately after annealing in air at 600°C. 5-δ MgTi2O 5-δ And MgTi2O after annealing in air at 1000℃ 5-δ Photos;

[0021] Figure 10 The original MgTi2O was shown 5-δ A comparison curve of corrosion current density of carbon paper and polished stainless steel (SS) 316.

[0022] Figure 11A and 11B MgTi2O, as a catalyst support material, is shown respectively. 5-δ A schematic diagram, in which the catalyst is deposited in the form of islands or in a core-shell structure.

[0023] Figure 12A and 12B Sputtering on MgTi2O before and after annealing 5-δ Cross-sectional scanning electron microscope (SEM) image of Pt on a non-limiting instance of pellets;

[0024] Figures 13A to 13D It was shown in MgTi2O 5-δ The interface formed by first-principles density functional theory (DFT) between the Pt surface and the Pt surface before and after DFT relaxation; and

[0025] Figure 14 It shows the adhesion of MgTi2O 5-δ Schematic diagram of various Pt particles / facets on an oxide support. Detailed Implementation

[0026] The following describes embodiments of this disclosure. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The drawings are not necessarily to scale; some features may be exaggerated or minimized to show detail of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to use the embodiments in various ways. As will be understood by those skilled in the art, the various features shown and described with reference to any of the drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of this disclosure may be desired for a particular application or implementation.

[0027] Unless otherwise expressly indicated, all numerical quantities representing dimensions or material properties in this specification should be understood to be modified by the word “about” when describing the broadest scope of this disclosure.

[0028] The initial definition of acronyms or other abbreviations applies to all subsequent uses of the same abbreviation herein, with necessary modifications to suit the normal grammatical variations of the originally defined abbreviations. Unless explicitly stated otherwise, performance is measured by the same technique referenced previously or later for the same performance.

[0029] The terms “substantially” or “about” are used herein to describe the disclosed or claimed embodiments. The terms “substantially” or “about” may modify values ​​or relative characteristics disclosed or claimed in this disclosure. In this case, “substantially” or “about” may mean that the value or relative characteristic it modifies is within ±0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or 10% of said value or relative characteristic.

[0030] A description of a group or class of materials applicable to a given purpose in relation to one or more embodiments implies that a mixture of any two or more members of that group or class is suitable. A description of components in chemical terms refers to the components when added to any combination listed in the specification, and does not necessarily exclude chemical interactions between the components of the mixture once mixed. The first definition of an acronym or other abbreviation applies to all subsequent uses of the same abbreviation herein, with necessary modifications to the normal grammatical variations applicable to the originally defined abbreviation. Unless expressly stated to the contrary, measurements of performance are determined by the same technique referenced previously or later for the same performance.

[0031] Metals are a widely used material in many industries, including automobiles, construction, home appliances, tools, piping, railway tracks, and minting. Metals have been used for thousands of years and remain the material of choice for some applications due to their properties such as strength and resilience. However, for many applications using metals, corrosion is a major source of fatigue and lifespan limitation.

[0032] Corrosion is a natural process that transforms refined metals into chemically more stable forms, such as oxides, hydroxides, sulfides, and / or salts of the metal. This transformation manifests as the gradual degradation of the metallic material, caused by electrochemical oxidation resulting from the reaction of the metal with oxidants such as oxygen or sulfates. Corrosion can be caused by exposing the metallic substrate to moisture in the air, solutions with relatively low pH, various chemicals such as acids, microorganisms, elevated temperatures, and / or other factors. Especially in acidic environments, corrosion begins at the interface between the bulk metallic material (e.g., steel) and the solution (e.g., ions dissolved in water or on the surface of water that react to degrade the bulk material).

[0033] Numerous efforts have been made to prevent or mitigate the corrosion of metals. For example, various types of coatings have been developed. Examples of coatings include applied coatings such as paints, platings, and enamels; reactive coatings containing corrosion inhibitors such as chromates, phosphates, conductive polymers, and surfactant-like chemicals designed to inhibit electrochemical reactions between the environment and the metal substrate; anodized surfaces; or biofilm coatings. Other corrosion protection methods include controlled permeability frameworks, cathodic protection, or anodic protection.

[0034] However, the most popular solution to corrosion problems remains strengthening vulnerable metal surfaces with coatings. Therefore, most corrosion-resistant surfaces include one or more chemically inert coatings or protective layers that can slow down and / or at least partially prevent corrosion. The challenge remains in finding materials that possess fundamental corrosion resistance, are also environmentally friendly and economical, and exhibit excellent performance characteristics.

[0035] Additionally, some applications are highly susceptible to corrosion due to their environmental factors. A non-limiting example of such an application is the proton exchange membrane fuel cell (PEMFC). PEMFCs are an environmentally friendly alternative to internal combustion engines in various vehicles such as cars and buses. PEMFCs typically feature relatively high efficiency and power density. A very attractive feature of PEMFC engines is their zero carbon emissions, provided that the hydrogen fuel is obtained in an environmentally friendly manner. Besides being a green engine, PEMFCs can also be used in other applications such as stationary and portable power sources.

[0036] The PEMFC's operating environment itself is susceptible to corrosion due to various factors. These include low voltage during PEMFC startup and shutdown, a highly acidic environment, the release of fluoride ions from the polymer membrane during operation, the presence of both H2 and O2 at the anode during startup and shutdown (leading to a high cathodic potential for cathodic corrosion), fuel cross-contamination of hydrogen or oxygen from the anode to the cathode, or vice versa, and so on. Therefore, PEMFCs require durable components capable of withstanding these conditions.

[0037] Figure 1 The image depicts a non-limiting example of a PEMFC. The core component of the PEMFC 10, which helps generate the electrochemical reactions required for electron separation, is the membrane electrode assembly (MEA) 12. The MEA 12 includes sub-components such as electrodes, catalysts, and polymer electrolyte membranes. In addition to the MEA 12, the PEMFC 10 typically includes other components such as a current collector 14, one or more gas diffusion layers 16, a liner 18, and one or more bipolar plates 20.

[0038] The bipolar plates, or BPPs 20, are implemented in the PEMFC stack to distribute gases, collect current, and separate the individual cells within the stack. BPPs 20 also provide additional functions such as removing reaction products and water, and thermal management within the PEMFC 10. BPPs 20 are also relatively expensive components and a common cause of degradation in PEMFC systems. For example, BPPs can constitute approximately 60-80% of the stack weight, approximately 50% of the stack volume, and approximately 25-45% of the stack cost. To maintain low cost, BPPs 20 are typically made of metal, such as steel, like stainless steel. Alternative materials such as aluminum or titanium can be used. Since metal plates are prone to corrosion within PEMFC systems, efforts have been made to prevent corrosion.

[0039] Furthermore, BPP 20 presents another material challenge within PEMFC 10, as it also needs to be conductive to facilitate electron transfer for the oxygen reduction reaction. Therefore, BPP 20 material needs to be conductive, but chemically inert to reactions with ions present in the PEMFC 10 environment.

[0040] Typically, BPP metal surfaces contain coatings such as graphite-like coatings or protective oxide or nitride coatings to increase the corrosion resistance of BPP 20. The surface of BPP 20 can therefore contain elements such as Fe, Cr, Ni, Mo, Mn, Si, P, C, S, F, or combinations thereof. Alternative coatings include Ti alloys and doped TiO₂. xCr2O3, TiO2, TiN, CrN, or ZrN. However, in corrosive environments such as PEMFC 10, where coatings are more likely to deteriorate faster than in other applications, there is still a need for economically viable, corrosion-resistant coatings or materials that are protective against acids such as HF at the PEMFC operating temperature of approximately 80°C, are conductive, and can simultaneously form a coherent interface with the metal substrate (i.e., low interfacial contact resistance).

[0041] The materials disclosed herein address one or more of the aforementioned problems and / or provide the benefits described herein. Surprisingly, the disclosed materials provide corrosion resistance and electrical conductivity to substrates such as BPP metal substrates. The materials comprise multiple or a series of Mg-Ti compounds with varying oxygen vacancy contents, or in other words, multiple Mg-Ti compounds with varying oxygen vacancy stoichiometry.

[0042] Non-limiting examples of BPP 20 are shown in Figure 2 BPP 20 represents a non-limiting example of a substrate having a solid body or body portion 22 and a surface portion 24. The body portion 22 may be formed of a metal such as steel, stainless steel, aluminum, copper, an alloy of two or more metals, or a combination thereof. Alternatively, the body portion 22 may be formed of a composite material such as a carbon-carbon composite or a carbon-polymer composite. Or, the body portion 22 may be made of graphite or other carbon allotropes. In another embodiment, the body portion 22 may also comprise the disclosed material.

[0043] The surface portion 24 may comprise a corrosion-resistant, chemically inert, electrically conductive, and thermodynamically stable material disclosed herein. The entire area of ​​the surface portion 24 may comprise the material. Alternatively, the surface portion 24 may comprise one or more sub-portions without the material. In one example embodiment, the entire surface portion 24 may comprise the material to protect the entire BPP 20 from corrosion. In other applications, such as non-BPP applications, only a small portion of the surface portion 24 may comprise the material, such as less than about 1 / 2, 1 / 4, 1 / 8, 1 / 16, 1 / 32, etc.

[0044] The surface portion 24, the body portion 22, or both may comprise one or more layers of the disclosed material. The thickness of the material on the surface portion 24 may be adjusted according to the needs of a particular application. Non-limiting examples of the material layer thickness may be about 0.1-0.8 µm, 0.2-0.6 µm, or 0.3-0.5 µm. Alternatively, the material can be layered to form a relatively thick deposit with a size greater than 1 μm on the surface portion 24, such as about or at least about 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.25, 3.5, 3.75, 4.0, 4.25, 4.5, 4.75, 5.0, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 200, 250. µm or approximately 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.25, 3.5, 3.75, 4.0, 4.25, 4.5, 4.75, 5.0, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 200, 250, 300, 350, 400, 450, or 500 nm. The material can be formed in one or more layers on the body portion 22. The material can be formed in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more layers on the body portion 22. Each layer may have a thickness in the nanometer or micrometer range, relative to the thickness of the surface portion 24.

[0045] The disclosed material is based on Mg-Ti-O. The disclosed material has formula (I):

[0046]

[0047] in

[0048] δ is any number from 0 to 3, optionally including a decimal part, such as tenths and / or hundredths, and represents oxygen vacancies. δ can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0. δ can be any number from 0 to 3, including tenths, hundredths, or both. δ can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, or 0. 40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.8 0, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.1, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1 .21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.73, 1.74, 1.75, 1.76, 1.77, 1.78, 1.79, 1.80, 1.81, 1.82, 1.83, 1.84, 1.85, 1.86, 1.87, 1.88, 1.89, 1.90, 1.91, 1.92, 1.93, 1.94, 1.95, 1 0.96, 1.97, 1.98, 1.99, 2.0, 2.01, 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 2.08, 2.09, 2.1, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19, 2.20, 2.21, 2.22, 2.23, 2.24, 2.25, 2.26, 2.27, 2.28, 2.29, 2.30, 2. 31, 2.32, 2.33, 2.34, 2.35, 2.36, 2.37, 2.38, 2.39, 2.40, 2.41, 2.42, 2.43, 2.44, 2.45, 2.46, 2.47, 2.48, 2.49, 2.50, 2.51, 2.52, 2.53, 2.54, 2.55, 2.56, 2.57, 2.58, 2.59, 2.60, 2.61, 2.62, 2.63, 2.64, 2.65, 2 2.66, 2.67, 2.68, 2.69, 2.70, 2.71, 2.72, 2.73, 2.74, 2.75, 2.76, 2.77, 2.78, 2.79, 2.80, 2.81, 2.82, 2.83, 2.84, 2.85, 2.86, 2.87, 2.88, 2.89, 2.90, 2.91, 2.92, 2.93, 2.94, 2.95, 2.96, 2.97, 2.98, 2.99, or 3.00.

[0049] δ can be a range that includes any of the numbers mentioned above, excluding at least one of the numbers mentioned above. For example, δ can be equal to 0.1-3.0, excluding 1 and 2. In an alternative instance, δ can include one or more ranges of 0.1-0.9, 1.1-1.9, or 2.1-2.9. In yet another non-limiting instance, δ can include one or more ranges of 0.01-0.99, 1.10-1.99, or 2.10-2.99.

[0050] In one or more embodiments, oxygen vacancies within the material contribute to the material's beneficial properties. Therefore, oxygen vacancies are intentionally formed and retained, and processes that would eliminate the presence of oxygen vacancies can be avoided or eliminated during the material's synthesis and / or use.

[0051] The oxygen vacancies in the material are characterized by the fact that the number of oxygen atoms present in the material is less than the expected number in the crystal lattice of the parent material. Oxygen vacancies are typically formed by removing oxygen from oxygen compounds, for example, by annealing in a reducing atmosphere such as N2, Ar, etc. In another embodiment, annealing can be performed in a vacuum furnace. The oxygen vacancies can make the material non-stoichiometric or deviate from stoichiometry, such that the elemental composition of the material may not be expressed by a well-defined ratio of natural numbers. However, the material can be stoichiometric.

[0052] In some applications, oxygen vacancies may be considered undesirable defects that affect structural, electrical, optical, dissociation and reduction properties, or other properties in ways unsuitable for various applications. Conversely, the materials disclosed herein exhibit desired properties due to the presence of oxygen vacancies. Although the base or parent compound and the materials with oxygen vacancies can have somewhat common morphologies, structures, or lattices, their properties can differ significantly. This is the case with the disclosed materials having oxygen-deficient stoichiometry. The materials have a crystalline structure similar to the parent MgTi2O5 phase. However, due to oxygen deficiency, even the crystalline structure differs. For example, the lattice of the disclosed materials may contain additional bonds or lack bonds in the spaces where the parent phase contains bonds. Examples of structural differences between the parent and disclosed materials can be seen in Figure 5. In Figure 5, the large dark gray circles represent Ti atoms, the large light gray circles represent Mg, the small black circles represent O atoms, and the small light gray circles represent H atoms.

[0053] As shown in Figure 5, the lattice of the parent MgTi₂O₅ phase contains Ti and Mg atoms. Each Ti atom has exactly four bonds with an oxygen atom, and each Mg atom has three or five bonds with an oxygen atom. Conversely, MgTi₂O₅... 5-δ The crystal structure contains at least one Ti atom with bonds to five oxygen atoms and / or at least one Mg atom with only four oxygen atoms.

[0054] This disclosure is not limited to a single theory; it is believed that due to the presence of oxygen vacancies, the disclosed material exhibits properties very different from the parent phase, such as electrical conductivity, because oxygen vacancies act as the primary charge carriers for electrical conduction in the material. Further differences can be observed in its physical appearance. While the parent structure is white, the disclosed material has a black to gray appearance with a deep blue tint, indicating the presence of oxygen vacancies. Figure 3 Examples of the synthesized materials can be seen in the figures, and color differences can be seen in Figures 9A-9C, which indicate oxygen vacancies.

[0055] The disclosed material exhibits good electrical conductivity. The MgTi2O 5-δThe material can exhibit an electrical conductivity of approximately 1-15, 1.5-12, or 2-10 S / m at room temperature in the surrounding environment. The MgTi₂O 5-δ The material may have an electrical conductivity of about, at least about, or up to about 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, or 15 S / m, or any range between these values, at room temperature in the surrounding environment.

[0056] Electrical conductivity can be determined by the band gap (E) g The band gap is used to represent the energy difference between the top of the valence band and the bottom of the conduction band. Materials with large band gaps are typically insulators, while those with smaller band gaps are called semiconductors. Conductors either have no band gap or have a band gap of 0 (i.e., metallic), or have a very small band gap such as (<1 eV) (i.e., half-metallic).

[0057] First-principles DFT calculations were performed to examine MgTi2O 5-δ The conductivity behavior was determined. Calculations were performed using the Perdew-Burke-Ernzerhof (PBE) formula with projected augmented wave potentials and the generalized gradient approximation (GGA) in the Vienna ab initio simulation software package (VASP). A plane wave basis cutoff energy of 520 eV was used.

[0058] For atomic simulations, orthogonal systems with 12 formula units are used. Cmcm A supercell of MgTi₂O₅ (space group 63) with a 3 x 3 x 3 grid at point k. From Figure 4A Density of states (DOS) simulations revealed that the bulk MgTi₂O₅ has a DFT band gap greater than 2 eV, indicating that the parent MgTi₂O₅ structure is an insulator. The Fermi level (E) F The value is set to x = 0. At the Fermi level (E... F The state below the Fermi level is occupied; and the state above the Fermi level is unoccupied.

[0059] On the contrary, such as Figure 4B As shown, the presence of oxygen vacancies in the bulk MgTi2O5 structure alters the material's electrical conductivity. Compared to the parent structure, the disclosed example sample MgTi2O 4.92 Fermi level (E F An offset has occurred. F It is occupied (i.e., metallic), indicating MgTi2O 5-δIt exhibits conductive behavior, which is further confirmed by the experiments discussed below.

[0060] DFT calculations were also used to evaluate the corrosion resistance behavior of the disclosed materials. DFT plate models were tested using hydrogen adsorption and dissociation reactions. (110)MgTi2O5, (110)MgTi2O 5-δ Hydrogen dissociation reactions were tested on the structures of (101)TiO2 (anatase), (110)TiO2 (rutile), and (001)TiO2, as shown in Figure 5. The maximum hydrogen coverage was tested for each plate model. Table 1 below shows the hydrogen adsorption energy (ΔH) for each plate model. E ads,H ) and maximum hydrogen coverage ( θ H,cov ).

[0061] Table 1 – Calculated hydrogen adsorption energy (Δ) E ads,H ) and maximum hydrogen coverage ( θ H,cov )

[0062] <![CDATA[MgTi2O5]]> <![CDATA[MgTi2O 5-δ ]]> <![CDATA[TiO2 (anatase)]]> <![CDATA[TiO 2 (Rutile) TiO <![CDATA[Δ E ads,H [eV / H]]]> 0.876 1.159 1.010 0.960 1.045 <![CDATA[ θ H,cov [%]]]> 71.4 30.8 100 100 100

[0063] As shown in Table 1, compared with other tested chemicals, (110)MgTi2O 5-δ It possesses the largest hydrogen adsorption energy. This finding is directly related to the (110)MgTi2O group tested. 5-δ The highest chemical resistance to H adsorption is related to this. Additionally, (110)MgTi2O 5-δ It exhibits the lowest hydrogen coverage (i.e., the least hydrogen dissociation).

[0064] The disclosed MgTi2O 5-δ The material may have a nominal chemical composition of approximately 25-40, 28-35, or 30-33 mol% MgO and 75-60, 72-65, or 70-66 mol% TiO + TiO2 mixture. The molar ratio of Mg to Ti, Mg / Ti, may be approximately 0.2-0.8, 0.3-0.60, or 0.4-0.5.

[0065] In one or more embodiments, the preparation of MgTi2O is disclosed. 5-δMethods for preparing materials. The synthesis may include preparing dry powders of MgO, TiO, and / or TiO2. The method may include forming a mixture of MgO, TiO, and / or TiO2. The method may include mixing a first powder of MgO and a second powder premixture of TiO / TiO2 or TiO. The method may include drying one or more compounds to be included in the mixture. Drying may be performed in a vacuum or ultra-high vacuum, N2, Ar, or Ar / H2 environment. Ultra-high vacuum refers to a pressure below approximately 10... −7 Pa or 100 NaPa (10 −9 millibars, ~10 −9 The situation of (to entrust).

[0066] The mixture can be compressed into any shape or configuration, for example, in a mold. A non-limiting example could be compressed pellets. The compressed mixture can be heated by sintering for a certain amount of time. Sintering is a process of compacting and forming solid clumps of material by heat and / or pressure without melting the material to its liquefaction point or melting point.

[0067] The specified time can be the time required for the powder particles to melt together and form a solid block and / or for the appearance of the compressed material to change from light gray to bluish-black. Sintering can be carried out at temperatures below the melting point of the powder mixture. In a vacuum, N2, Ar, or Ar / H2 environment, the temperature can be in the range of approximately 400 to 2000 °C, 800 to 1800 °C, or 1200 to 1500 °C.

[0068] The amount of oxygen vacancies can be customized to meet the needs of a specific application. The amount of oxygen vacancies can be introduced, controlled, or altered by controlling, adjusting, or controlling the sintering temperature. The amount of oxygen vacancies can be controlled by the TiO / TiO2 ratio in the powder mixture. The TiO / TiO2 ratio can be approximately 0:100, 1:99, 10:90, 20:80, 30:70, 40:80, 50:50, 60:40, 70:30, 80:20, 90:10, 99:1, or 100:0.

[0069] Surprisingly, it was found that, contrary to sintering, annealing destroyed oxygen vacancies in the disclosed material. Since oxygen vacancies are desirable in the disclosed material, annealing should be avoided as a process that minimizes crystal defects through heat treatment, which involves heating the material above its recrystallization temperature, holding it at the appropriate temperature for a certain period of time, and then cooling it in air.

[0070] MgTi2O on metal bipolar plates 5-δ The coating can be achieved using various deposition techniques. A non-limiting example could be spraying a solvent-based MgTi2O coating onto a BPP plate. 5-δThen a drying process is performed. Alternatively, the method may include physical or chemical vapor deposition. As another alternative, atomic layer deposition (ALD) can be performed on a metallic substrate. Depending on the choice of precursor, oxidizing or reducing environment, humidity, and substrate, MgTi2O 5-δ The degree of oxygen vacancies can vary, leading to different electrical conductivities and corrosion resistance behaviors. For example, under more oxidizing conditions, MgTi2O 5-δ The surface portion can be more insulating, or vice versa.

[0071] The disclosed materials can be used in applications requiring both corrosion resistance and good electrical conductivity. For example, the disclosed materials can be used as BPP coatings, for BPP body portions, for BPP surface portions, or combinations thereof. Alternatively, the disclosed materials can be used as corrosion-resistant coatings in automotive parts, aerospace components, oil and gas plants, or large-scale manufacturing. In an alternative embodiment, the disclosed materials can be used as catalyst support materials, such as for PEMFC applications or other catalytic applications, as further discussed below. Example

[0072] Group A

[0073] To verify the results of the DFT derivation, the disclosed material was synthesized and tested according to the method described below.

[0074] The disclosed material was synthesized using a mixture of dried MgO, TiO, and TiO2 powders by the following method: MgO powder was dried at 120°C for 2 hours in an Ar environment. The dried powder was then mixed with TiO / TiO2 powder to form a mixture. The mixture was pressed into pellets with a measured diameter of approximately 12 mm and a thickness of approximately 2 mm under a uniaxial load of 3000 psi. The freshly pressed pellets were light gray. The compacted pellets were then placed in an Al2O3 crucible and heated under vacuum (10 °C). -3 The pellets are reactively sintered (e.g., at 1450°C) for 10 hours. After sintering, the pellets appear black with a bluish tint. This method was used to prepare five batches of pellets, each batch containing three to four pellets.

[0075] Five sintered pellets (one per batch) were sputtered with Au on both sides of their surface. The pellets were then assembled into EL-Cell® ECC cells. A constant current was applied, and the voltage was recorded after approximately 10 minutes until the voltage reading stabilized. This step was repeated several times at different currents. The resistance and DC conductivity were calculated by fitting a linear slope to the VI data.

[0076] Figure 6An Arrhenius curve of conductivity from 25°C to 80°C is shown. Average conductivity and error bars were calculated from seven different samples prepared from different batches. The disclosed crystalline MgTi₂O 5-δ The material exhibits an electrical conductivity of approximately 2–10 S / m at room temperature in the ambient environment. The measured conductivity is higher than that of semiconductors such as Ge and Si, but slightly lower than that of carbon, iron, and gold. The activation energy of the material is approximately 0.13 eV over a temperature range of 25°C to 80°C.

[0077] The physical properties of the disclosed material from several pellets from two different batches were evaluated using X-ray photoelectron spectroscopy (XPS) and optical microscopy. For observational purposes, some of the pellets were annealed. These pellets were compared with TiO2 control pellets. XPS studies of these pellets were performed using a PHI XPS system equipped with an Al X-ray source (incident photon energy 1486.7 eV). The pore size was set to approximately 1.1 mm in diameter. The binding energy of the resulting XPS spectra was calibrated relative to the C 1s peak of the foreign carbon at 284.8 eV.

[0078] Figure 7 The Ti 2p XPS spectra of pellets containing the disclosed material in its pristine state, pellets containing the disclosed material annealed in air, and TiO2 reference pellets are shown. The collected data indicate that the Ti in the pellets containing the disclosed material in its pristine state is predominantly in the Ti 4+ state, similar to the Ti in the pellets containing the disclosed material annealed in air and the TiO2 reference pellets. Observation and XRD analysis also indicate that the disclosed material has a crystal structure similar to, but not identical to, MgTi2O5. Figure 8 As can be seen in the text.

[0079] Optical evaluation of the sintered pellets. The surface of the sintered pellets is visible in Figure 9A, showing synthetic pellets characterized by black and blue hues on the surface. Three of the sintered pellets were annealed in air at 600°C for 10 hours. As can be observed in Figure 9B, the surface of the annealed pellets partially changed at the edges of the pellets, and some surface areas of these pellets turned white, while some surfaces remained black. The annealed pellets were further exposed to air at 1000°C for an additional 10 hours of annealing. Figure 9C As can be seen, after the second round of annealing, the entire surface of these pellets turned white. Optical images of the pellets shown in Figures 9A-C were collected using a Keyence VHX microscope at magnifications ranging from 100x to 1000x.

[0080] The conductivity of the freshly synthesized pellets was assessed to be approximately 1.7-8 S / m, while the conductivity of the annealed pellets shown in Figure 9B was found to be lower than that of the freshly synthesized pellets, at 0.36 S / m. Figure 9C The annealed pellets shown were evaluated as insulating. The results indicate that color and conductivity are related to oxygen vacancies in the material. Not limiting this disclosure to a single theory, it is believed that annealing in air eliminates oxygen vacancies, which subsequently leads to color change and conductivity loss. Figures 9A-C suggest that oxygen vacancies are the primary charge carriers for conductivity in the disclosed materials. When oxygen vacancies are eliminated through annealing in air at 1000°C or otherwise, the material transforms into an insulator.

[0081] Further testing was conducted on the corrosion resistance of the newly synthesized pellets. Corrosion current measurements were performed using a three-electrode liquid cell apparatus. The counter electrode was approximately 16 cm². 2 A Pt mesh was used. The reference electrode was a standard Ag / AgCl electrode in KCl solution. Pellet pellets were used as the effective area, approximately 0.5 cm². 2 The working electrode was used. One pellet was measured at a time for each measurement. A total of three pellets were measured. For static corrosion current measurements, sulfuric acid with pH = 2 was used as the electrolyte at 60°C. The static corrosion current was recorded at a bias voltage of 1.0 V relative to an Ag / AgCl reference electrode.

[0082] The results of corrosion current measurement are shown in Figure 10 The corrosion current density of the newly synthesized, original, and disclosed material is shown at the bottom, with carbon paper at the top and polished stainless steel (SS) 316 in the middle. Original MgTi2O 5-δ The corrosion current density of the material was evaluated to be approximately two orders of magnitude better / lower than polished SS316 and carbon paper. In other words, in MgTi2O... 5-δ The corrosion current measured in the sample indicates that, compared to SS316, MgTi2O 5-δ It generates a stable corrosion current that is 100 times smaller. Overall, the crystalline MgTi2O... 5-δ The material exhibits good corrosion resistance in acidic environments.

[0083] The MgTi2O 5-δ The material exhibits a molecular weight variation of less than approximately 0.5-5, 1-3, or 1.5-2.5 μA cm⁻¹ at pH 2 and temperatures of approximately 0-80°C, 10-60°C, or 20-40°C. -2 The corrosion resistance (static corrosion current density) of the MgTi2O 5-δThe material exhibits properties of less than approximately 5.0, 4.0, 3.0, 2.5, 2.0, 1.8, 1.6, 1.4, 1.2, 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1 μA cm⁻¹ at pH 2 and temperatures ranging from approximately 0–80 °C, 10–60 °C, or 20–40 °C. -2 Its corrosion resistance.

[0084] The chemical resistance, or inertness, of the pellets was also tested. Chemical inertness involves the interaction of the material with compounds such as H3O present in acidic fuel cell environments. + F - and SO4 - The reactivity was tested by pulverizing a raw pellet into powder and then placing it in aqua regia (a mixture of concentrated HNO3 and HCl in a 3:1 ratio) heated to 100-150°C. The powder did not dissolve, indicating good chemical stability.

[0085] In one or more non-limiting embodiments, the disclosed materials can be used as catalyst supports in a PEMFC. In a PEMFC, both the anode and cathode may contain catalysts that promote the reaction of oxygen and hydrogen. The anode catalyst oxidizes the fuel to hydrogen protons and electrons at the anode, while the cathode catalyst catalyzes the oxygen reduction reaction to form water. Because the chemistry at the cathode is more complex, a higher catalyst loading is typically required at the cathode than at the anode to increase the reaction rate.

[0086] A suitable catalyst must be sufficiently stable to withstand the corrosive environment at the cathode and must possess sufficient chemical activity to reduce O2. The catalyst must also exhibit sufficient selectivity to produce the desired product while minimizing the formation of undesirable intermediates. Once the reaction is complete, the catalyst layer should also facilitate the release of product water from the catalyst surface to free up catalytic sites.

[0087] Many precious metals have been used as catalysts. The most commonly used catalyst is platinum (Pt) because of its excellent catalytic activity and moderate stability to withstand its harsh operating conditions. In fact, Pt is one of the few elements that can withstand the acidic (pH < 2) operating environment of fuel cells.

[0088] Typically, to increase catalyst stability and prevent physical separation from the system, catalyst materials are immobilized onto a catalyst support material, which is usually a solid material with a high surface area. The catalyst support itself needs to be inert to prevent interference with the catalytic reaction. The most common catalyst supports used in PEMFCs include graphite, carbon nanofibers, carbon nanotubes, nanospheres, nanoellipsoids, nanorods, etc., or combinations thereof.

[0089] However, under fuel cell operating conditions, especially during start-up / shutdown, oxidation of these support materials can occur, which in turn can lead to catalyst degradation, potentially limiting the PEMFC lifetime. For carbon-based supports, this phenomenon is called carbon corrosion. Therefore, various metal oxides, the opposite of carbon, have been investigated as potential alternative catalyst supports due to their tendency to improve catalyst stability and resistance to further oxidation.

[0090] Any catalyst support material needs to meet certain criteria—stability under PEMFC operating conditions, which are typically acidic (i.e., low pH, pH 1–4), and the ability to withstand varying voltages applied to the fuel cell (typically 0 V to ~1.2 V relative to the SHE).

[0091] Among the various metal oxides used as catalyst support materials in PEMFC electrodes, TiO2 and SnO2 have been disclosed as leading candidates. This is due to their stability in aqueous electrochemical systems: forming stable oxides where pH can vary from 1 to 4 (i.e., acidic), and voltages from 0 to 1.23 V also affect the local environment during PEMFC operation. Recently, Sn-doped TiO2 has also been tested as a catalyst support material for Pt catalysts, and the following results have been reported: 1) Doping up to 10% Sn in TiO2 leads to increased mass activity; 2) Catalyst supports with 23-40% Sn in TiO2 require significantly less Pt; 3) Sn-doped TiO2 is stable under acidic conditions at 80 °C when <28% Sn is doped in TiO2.

[0092] In one or more embodiments, the material of formula (I) disclosed herein may be used as a metal oxide support for a PEMFC catalyst in a fuel cell application, on the cathode, anode, or both. The catalyst may be a noble metal or a noble metal-free catalyst. Non-limiting examples of the catalyst may be Pt, Pd, Au, Ir, Rh, Ru, or combinations thereof. The catalyst may be a redox reaction (ORR) catalyst.

[0093] The catalyst can be deposited on MgTi2O 5-δ In metal oxide materials, either as Figure 11A As shown, one or more catalyst islands are formed on the catalyst support, or as... Figure 11B The diagram shows a core-shell configuration, in which MgTi2O 5-δ A core is formed and the catalyst forms a shell. In Figure 11A and 11BIn this diagram, 50 represents the catalyst support and 52 represents the catalyst. Specific configurations can be tailored to meet the expected performance, cost, and lifetime of the PEMFC unit and / or stack system. MgTi2O is used as the catalyst support material. 5-δ Cross-sectional images of Pt used as a catalyst and obtained by scanning electron microscopy (SEM) are shown in the figure. Figure 12A and 12B The catalyst support material may have a flat or uneven surface. The catalyst support material may be used as a substrate for the catalyst material. The catalyst support material may be physically and / or chemically bonded to the catalyst.

[0094] As demonstrated in this paper, MgTi2O 5-δ The catalyst support material is chemically stable in acidic environments and exhibits high electrochemical stability against corrosive and oxidative environments during fuel cell operation.

[0095] DFT calculations were performed to construct a Pt metal catalyst with MgTi2O 5-δ The interface between Pt and MgTi2O was determined. DFT calculations were performed using the Perdew-Burke-Ernzerhof (PBE) formula with the projected augmented wave potential and the generalized gradient approximation (GGA) in the Vienna ab initio simulation software package (VASP). A plane wave basis set cutoff energy of 520 eV was used. DFT calculations were used to verify the Pt and MgTi2O interfaces. 5-δ A stable interface can be formed, which allows MgTi2O to... 5-δ Oxide support materials that can be used as PEMFC catalysts.

[0096] Table 2 below shows the DFT calculations for Pt catalyst and MgTi2O 5-δ Interfacial energy between supports. Specifically, in (110)MgTi2O 5-δ The energy-stable Pt surface facets (111), (100), and (110) were examined. Table 2 illustrates the (110)MgTi2O 5-δ The calculated DFT interfacial energy (without considering facets) between Pt and the catalyst was predicted to be negative. A negative DFT interfacial energy indicates that a stable interface will form between the two chemical systems. Table 2 further shows the DFT interfacial energies of Pt on TiO2 and SnO2 for comparison. As can be seen in Table 2, MgTi2O 5-δ The interfacial properties are comparable to those of SnO2 / TiO2. For DFT calculations, Δ E 界面 = E 0,总 –( E 0,Pt,表面 + E 0,MOx ), of which internal energy (E 0) can be obtained by DFT calculation.

[0097] Table 2 – Calculated DFT interfacial energies (Δ) between Pt catalysts and various oxide support materials E 界面 )

[0098] DFT interface between Pt surface and oxide support material <![CDATA[Δ E 界面 [J / m 2 ]]]> picture <![CDATA[(111) Pt || (110) MgTi2O 5-δ ]]> -1.83 13B, 13E <![CDATA[(100) Pt || (110) MgTi2O 5-δ ]]> -2.01 13A, 13D <![CDATA[(110) Pt || (110) MgTi2O 5-δ ]]> -1.35 13C, 13F <![CDATA[(111) Pt || (101) TiO2 (anatase)]]> -1.48 - <![CDATA[(111) Pt || (110) SnO2 (rutile)]]> -1.93 -

[0099] Figure 13A -F shows various Pt surface facets with (110)MgTi2O before and after the DFT relaxation calculation. 5-δ The interface constructed between them. Specifically, Figure 13A -C displays the interface constructed before DFT relaxation. Figure 13D -F displays the interface after DFT relaxation. (By...) Figure 13D -F clearly shows that after DFT relaxation, MgTi2O 5-δ Pt (100) and Pt (111) on the above look very similar to each other.

[0100] Table 1 further shows that (100)Pt in (110)MgTi2O 5-δ The strongest bonding can occur between (110)Pt and (110)MgTi2O. 5-δ The bonding is relatively weak. Although the (111) facet appears to be the most energy-favorable surface facet in Pt nanoparticles, (110) and (100) facets were also observed at the corners and edges of the Pt particles. The size and shape of the Pt nanoparticles can be controlled according to the synthesis temperature, time, pH, precursor materials, and route, such as Figure 14 As shown in Table 2, all Pt facets are bonded to MgTi2O. 5-δ The (100) and (111) facets bond more strongly than (110). Therefore, DFT calculations show that Pt catalysts bond better with MgTi2O regardless of particle size and shape. 5-δ A stable interface will be formed between them.

[0101] The electrical conductivity and corrosion resistance of the disclosed materials as catalyst supports were further investigated. Table 3 below shows the DFT binding energies (ΔF) of H₂O and H₃O on Pt supported by various metal oxide supports. E b It also provides the relative binding energy (Δ). E rel,b The binding energy on pure Pt (111) is used as a reference value (i.e., zero energy). Loaded on MgTi2O 5-δThe calculated binding energy between Pt loaded on SnO2 and TiO2 is calculated for H2O and H3O. This indicates that MgTi2O 5-δ Pt loaded on SnO2 can provide higher stability than Pt loaded on SnO2, and it can provide higher reactivity compared to Pt loaded on TiO2.

[0102] Table 3 – DFT binding energies (Δ) of H₂O and H₃O on Pt supported by various metal oxide supports E b )

[0103] DFT interface between Pt surface and oxide support material <![CDATA[Δ E b,H2O [eV]]> <![CDATA[Δ E relb,H2O [eV]]> <![CDATA[Δ E b,H3O [eV]]> <![CDATA[Δ E relb,H3O [eV]]> <![CDATA[(111) Pt || (110) MgTi2O 5-δ ]]> -0.311 -0.157 -0.634 -0.227 <![CDATA[(100) Pt || (110) MgTi2O 5-δ ]]> -0.217 -0.063 -0.588 -0.181 <![CDATA[(110) Pt || (110) MgTi2O 5-δ ]]> -0.309 -0.155 -0.497 -0.090 <![CDATA[(111) Pt || (101) TiO2 (anatase)]]> -0.080 +0.074 -0.349 +0.058 <![CDATA[(111) Pt || (110) SnO2 (rutile)]]> -0.492 -0.338 -0.837 -0.430 Pure (111) Pt -0.154 - -0.407 -

[0104] As can be seen from Table 3, for MgTi2O 5-δ The relative binding energy of Pt on H2O ranges from -0.063 to -0.157 eV. For H3O, the binding energy varies from -0.090 eV to -0.027 eV. In both cases, this binding energy is lower than that of Pt loaded on TiO2, but higher than that of Pt loaded on SnO2. Therefore, as described above, MgTi2O 5-x The Pt on the substrate exhibits higher "stability" to reactants than Pt supported on SnO2, and higher "reactivity" than Pt on TiO2. Furthermore, as discussed above and respectively... Figure 6 and 10 The MgTi2O mentioned in the text 5-δ The material's corrosion resistance and enhanced electrical conductivity offer advantages over current TiO2 and SnO2 catalyst support systems for MgTi2O3. 5-δ Additional advantages of using materials as catalyst supports.

[0105] MgTi2O 5-δ Catalyst support materials can be prepared by various methods, including but not limited to solution-based methods, solid-state methods, thermal treatment, and / or electrochemical methods. The catalyst support material can be undoped and / or partially doped with nitrogen, carbon, fluorine, or other elements to further enhance conductivity. Non-limiting examples of other elements may include others. d 0 Metals such as Zr 4+ Hf 4+ V 5+ and / or Cr 6+ , and / or d 10 Metals such as Zn 2+ Ga 3+ and / or Pb 4+ , and Al 3+ (none d(electronic), of which d 0 and d 10 Metals and Al 3+ It is usually more difficult to oxidize.

[0106] Non-limiting examples of preparation methods may include using metal-containing precursor chemicals such as M(NO3) or MCl. x M(OH) x and MO x The catalyst is dissolved in a solvent to form an initial mixture, wherein M = Mg and Ti. The solvent can be water or an organic solvent. The pH of the solution can be adjusted, maintained, or controlled by the presence of oxidizing or reducing chemicals. The initial mixture can be heat-treated at approximately 100-2000°C, 200-1500°C, or 300-1000°C for different aging times of approximately 1, 2, 3, 4, 8, 12, 16, 24, 36, 48, 60, or 72 hours to form a catalyst support material. During the heat treatment, the gaseous environment can be controlled by N2, Ar, H2, O2, air, and / or vacuum. Subsequently, a catalyst material such as Pt can be deposited on the catalyst support material using solid-state, solution-based methods and / or various deposition techniques.

[0107] Oxide precursor materials of various sizes, such as MgO, TiO, TiO2, and Mg(OH)2, can be mixed and synthesized by solid-state methods such as ball milling, and then subjected to secondary heat treatment.

[0108] The MgTi2O 5-δ The catalyst support can be prepared into high surface area particles via a hydrothermal method followed by annealing in an oxygen-free atmosphere. The MgTi2O 5-δ Non-limiting examples of catalyst supports, BET can be about 100-1500, 150-850, or 200-550 m. 2 / g. The MgTi2O 5-δ Non-limiting examples of catalyst supports, BET, may be about, at least about, or up to about 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, or 1500 m. 2 / g or any range between. In contrast, Vulcan XC-72 material typically has 250 m 2 / g BET specific surface area; high surface area carbon can have up to about 1500 m 2BET specific surface area per g: for example, Ketjen Black EC 600JD, Ultra High Surface Area Carbon (USAC), etc.

[0109] The MgTi2O 5-δ Another non-limiting example of a catalyst support is a BET specific surface area of ​​less than 100 m². 2 / g, such as 0.1-99, 1-50 or 5-25 m 2 / g. The MgTi2O 5-δ The BET specific surface area of ​​the catalyst support can be about, at least about, or as high as about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or 5.0. 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 99 m 2 / g or any range between / g and .

[0110] Alternatively, the MgTi2O 5-δ Catalyst support materials can be prepared by chemical reaction in a vacuum, N2, Ar, or Ar / H2 environment at relatively high temperatures of approximately 400-2000℃, 800-1800℃, or 1200-1500℃, followed by mechanical grinding. The preparation atmosphere should be kept oxygen-free so that no oxygen is supplied during the reaction and it is actively removed from the reaction environment. MgTi2O 5-δ The catalyst support can be prepared via a colloidal synthesis route followed by a subsequent annealing step in different atmospheres. The catalyst support can also be prepared via combustion synthesis or flame synthesis followed by a subsequent annealing step in an oxygen-free environment.

[0111] The disclosed materials can be used for catalysis in a variety of applications, including PEMFCs, anion exchange membrane fuel cells (AEMFCs) at the cathode or anode, proton exchange membrane electrolyzers, chemical synthesis, air purification, including the purification of exhaust gases from internal combustion engines, photocatalysis for water splitting batteries, or photocatalysis for redox media for water purification.

[0112] The MgTi2O 5-δThe catalyst support material can be further mixed with carbon and / or another type of conductive polymer to increase conductivity. Carbon includes, but is not limited to, amorphous carbon, Denka black, Ketjen black, acetylene black, carbon nanotubes, carbon fibers, graphene, graphite, graphyne, graphene oxide, reduced graphene oxide, etc. The ratio of the mixture can be about 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, or 2:1. Alternatively, carbon and / or another type of additional support material can form one or more additional sublayers, which serve as a support for the disclosed material.

[0113] The MgTi2O 5-x The catalyst support material can be mixed with one or more types of catalyst support materials such as oxides, carbides, or intermetallic compounds. Examples of oxide materials may include SnO2, MoO3, Nb2O5, Ta2O5, TiO2, WO3, SnMo4O6 and / or TiNb3O6, GeO2, MoO2, NbO2, SnO, Ti3O5, SnWO4, WO2, Nb2SnO6, Sn2WO5, SnGeO3, Ta2SnO6, TiSn2O4, Ti6O, or mixtures thereof. Examples of carbides may include Nb6C5, Mo2C, Ta2C, Ti8C5, WC, TaC, Nb2SnC, Ti2GeC, Ti3SnC2, Ti3GeC2, MoC, or mixtures thereof. Non-limiting examples of binary or ternary intermetallic compounds may include MoW, NbSn2, Nb3Sn, Sn2Mo, TaSn2, Ta3Sn, TaW3, TiMo, TiMo3, Ti2Mo, Ti3Mo, TiNb, Ti2Sn, Ti2Sn3, Ti3Sn, Ti6Sn5, NbMo2W, TaMo2W, TiMo2W, Ti2NbSn, GeMo3, Ge2Mo, NbGe2, Nb5Ge3, SnGe, TaGe2, Ta3Ge, Ta5Ge3, TiGe2, Ti5Ge3, Ti6Ge5, or mixtures thereof. Depending on the secondary heat treatment conditions such as temperature and the presence of oxidizing / reducing agents, the amount (and composition) of oxides in the surface film and bulk region of the intermetallic compound can be further controlled. Example

[0114] Group B

[0115] To verify the results of the DFT calculations, the disclosed materials were used to form pellets using the method described in Example A above. Subsequently, a catalyst material containing Pt was sputtered onto the pellets, and the catalyst support with the catalyst was exposed to annealing at 600°C for 10 hours. Figure 12A An example of one of the pellets containing sputtered catalyst prior to the annealing process is shown. Figure 12B This shows one of the pellets after the annealing process. The dashed line indicates... Figure 12A Pt and MgTi2O in B 5-δ The interface between them. Figure 12A and 12B It is a cross-sectional image from a scanning electron microscope (SEM). Figure 12B This demonstrates the role of Pt catalysts in MgTi2O 5-δ The bond between Pt and MgTi2O is excellent. No phase separation was observed. Experiments show that Pt and MgTi2O are well bonded. 5-δ The materials formed good contact. Even after heat treatment at 600℃ for 10 hours, Pt and MgTi2O maintained good contact. 5-δ The material surfaces remain in close contact, indicating good contact.

[0116] The processes, methods, or algorithms disclosed herein can be transferred to, or implemented by, a processing device, controller, or computer, which may include any existing programmable electronic control unit or dedicated electronic control unit. Similarly, the processes, methods, or algorithms can be stored in a variety of forms as controller- or computer-executable data and instructions, including but not limited to information permanently stored on non-writable storage media such as ROM devices and information reproducibly stored on writable storage media such as floppy disks, magnetic tapes, CDs, RAM devices, and other magnetic and optical media. The processes, methods, or algorithms can also be implemented in a software executable object. Alternatively, the processes, methods, or algorithms can be implemented, wholly or partially, using appropriate hardware components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices, or a combination of hardware, software, and firmware components.

[0117] The following application relates to this application: U.S. Patent Application Serial No. 16 / 675,538, filed on November 6, 2019, which is incorporated herein by reference in its entirety.

[0118] While exemplary embodiments have been described above, they are not intended to describe all possible forms included in the claims. The language used in this specification is descriptive and not restrictive, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure. As previously stated, features of the various embodiments may be combined to form other embodiments that may not be explicitly described or shown. Although various embodiments may be described as offering advantages or superiority over other embodiments or prior art in one or more desired characteristics, those skilled in the art will recognize that one or more features or characteristics can be compromised to achieve the desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, availability, weight, manufacturability, ease of assembly, etc. Therefore, for any embodiment described as being less desirable in one or more features compared to other embodiments or prior art implementations, these embodiments are not outside the scope of this disclosure and may be desirable for a particular application.

Claims

1. A fuel cell catalyst system, comprising: catalyst; and A catalyst support material, which incorporates the catalyst and comprises a corrosion-resistant, conductive, non-stoichiometric material having oxygen vacancies according to formula (I): in δ is any number from 0 to 3 representing oxygen vacancies, including the decimal part. The non-stoichiometric material has an electrical conductivity of 2-10 S / m at room temperature in the surrounding environment.

2. The catalyst system according to claim 1, wherein the static corrosion current density of the catalyst support material is less than 1 μA cm⁻¹ at pH 2 and a temperature of 0-80°C. -2 .

3. The catalyst system according to claim 1, wherein the Mg / Ti ratio of the non-stoichiometric material is a number in the range of 0.3-0.

6.

4. The catalyst system according to claim 1, wherein the catalyst is a redox reaction catalyst.

5. The catalyst system according to claim 1, wherein the catalyst comprises at least some Pt(100) surface facets.

6. The catalyst system according to claim 5, wherein the catalyst forms at least one island on the catalyst support material.

7. Corrosion-resistant, conductive, non-stoichiometric materials, comprising: The crystal structure of a metal oxide with oxygen vacancies, as shown in formula (I): Where δ is any number from 0 to 3 representing oxygen vacancies, including the decimal part. The non-stoichiometric material has a nominal chemical composition of 33 mol% MgO and 66 mol% TiO and TiO2 mixture and an electrical conductivity of 2-10 S / m at room temperature in the ambient environment.

8. The material according to claim 7, wherein the Mg / Ti ratio of the material is a number in the range of 0.3-0.

6.

9. The material according to claim 7, wherein the static corrosion current density of the material is less than 1 μA cm⁻¹ at a temperature of 0-80°C when the pH is 2. -2 .

10. The material according to claim 7, wherein the material is a fuel cell catalyst support material.

11. A catalyst support comprising: Corrosion-resistant, conductive crystalline nonstoichiometric material with oxygen vacancies of formula (I): Where δ is any number from 0 to 3 representing oxygen vacancies, including the decimal part. The crystalline nonstoichiometric material has an electrical conductivity of 2-10 S / m at room temperature in the surrounding environment.

12. The catalyst support according to claim 11, wherein the catalyst is a cathode fuel cell catalyst.

13. The catalyst support according to claim 11, wherein the static corrosion current density of the non-stoichiometric material is less than 1 μA cm⁻¹ at pH 2 and a temperature of 0-80°C. -2 .

14. The catalyst support according to claim 11, wherein the Mg / Ti ratio of the non-stoichiometric material is a number in the range of 0.3-0.

6.

15. The catalyst support according to claim 11, wherein the non-stoichiometric material has an activation energy of 0.13 eV in a temperature range of 25˚C to 80˚C.

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