Search

CN-121986193-A - Anode for PEM water electrolysis cell and preparation method and application thereof

CN121986193ACN 121986193 ACN121986193 ACN 121986193ACN-121986193-A

Abstract

The invention provides an anode for a PEM water electrolytic cell and a preparation method thereof, the anode comprises a stainless steel matrix and a layered oxide structure generated on the surface of the stainless steel matrix in situ, wherein the layered oxide structure comprises a manganese-poor inner layer and a manganese-rich outer layer, and the manganese-rich outer layer comprises a crystalline manganese oxide secondary outer layer and an amorphous iron-containing manganese oxide outermost layer. The layered oxide structure on the surface of the anode can keep the catalytic activity and stability of the electrolyzed water for a long time under the acidic condition, and the proper selection of the surface structural components solves the problems of corrosion and stability of the self-catalytic non-noble metal electrode under the acidic environment. The proposal of the anode of the invention obviously reduces the cost of producing hydrogen based on noble metal catalyst at present, and is hopeful to solve the problem of high cost of large-scale electrolytic hydrogen production of PEM.

Inventors

  • HUANG MINGXIN
  • CHEN XIAOLING

Assignees

  • 香港大学

Dates

Publication Date
20260505
Application Date
20241101
Priority Date
20231107

Claims (17)

  1. An anode for a PEM water electrolyser comprising a stainless steel substrate and a layered oxide structure formed in situ on the surface of said stainless steel substrate, wherein said layered oxide structure comprises a manganese-depleted inner layer and a manganese-enriched outer layer, wherein said manganese-enriched outer layer comprises a crystalline manganese oxide minor outer layer and an amorphous iron-containing manganese oxide outermost layer.
  2. The anode of claim 1, wherein the layered oxide structure has a thickness of 100-800nm.
  3. The anode of claim 1, wherein the crystalline manganese oxide minor outer layer comprises 70-90% by volume of the manganese rich outer layer.
  4. The anode of claim 1, wherein the manganese-rich outer layer has a thickness of 50-300nm.
  5. The anode of claim 1, wherein the manganese-depleted inner layer has a thickness of 100-500nm.
  6. The anode according to claim 1, wherein the alloy composition of the stainless steel matrix comprises, by mass, 12% -25% of Cr, 15% -25% of Mn, 10% -20% of Co and/or Ni, 0-2.5% of Si, and the balance of Fe and unavoidable impurities.
  7. The anode of claim 1, wherein the manganese-depleted inner layer comprises chromium oxide particles, and cobalt-rich grains and/or nickel-rich grains.
  8. The anode of claim 1, wherein the manganese content of the manganese-depleted inner layer is less than 10wt%.
  9. The anode of claim 6 wherein the chromium oxide comprises 30-60% by volume of the manganese-depleted inner layer.
  10. The anode of any one of claims 1 to 8, wherein the anode produces an oxygen evolution current density greater than 0.5mA/cm 2 at a potential above 1.65v vs.
  11. The anode of any one of claims 1 to 8, wherein the anode has an oxygen evolution current density in the range of 0.1-5mA/cm 2 at a potential of 1.60V-1.73V vs.
  12. The anode of any one of claims 1 to 8, wherein the anode is maintained at a stable oxygen evolution current density under acidic electrolyzed water conditions for a time of at least 100 hours.
  13. A method of making an anode for a PEM water electrolyser, the method comprising heating a stainless steel substrate to 500-600 ℃ in air and incubating for 10-30 hours to generate a layered oxide structure in situ on the surface of the stainless steel substrate, wherein the layered oxide structure comprises a manganese-depleted inner layer and a manganese-enriched outer layer, wherein the manganese-enriched outer layer comprises a crystalline manganese oxide minor outer layer and an amorphous iron-containing manganese oxide outermost layer.
  14. The production method according to claim 12, wherein the alloy composition of the stainless steel matrix contains, by mass, 12% -25% of Cr, 15% -25% of Mn, 10% -20% of Co and/or Ni, 0-2.5% of Si, and the balance of Fe and unavoidable impurities.
  15. The method of claim 12, wherein the crystalline manganese oxide minor outer layer comprises 70-90% by volume of the manganese rich outer layer.
  16. A method of regenerating a spent anode, wherein the anode is an anode for a PEM water electrolyser as claimed in any one of claims 1 to 11, said method comprising removing residual layered oxide structure from the surface of a stainless steel substrate by grinding or ultrasonic cleaning, then heating the stainless steel substrate to 500-600 ℃ in air and holding for 10-30 hours to form layered oxide structure in situ on the surface of the stainless steel substrate, wherein the layered oxide structure comprises a manganese-depleted inner layer and a manganese-enriched outer layer, wherein the manganese-enriched outer layer comprises a crystalline manganese oxide minor outer layer and an amorphous iron-containing manganese oxide outermost layer.
  17. PEM water electrolyser the anode of which comprises an anode according to any one of claims 1 to 11, an anode produced according to the production method of any one of claims 12 to 14 or an anode regenerated according to the method of claim 15.

Description

Anode for PEM water electrolysis cell and preparation method and application thereof Technical Field The invention belongs to the field of material science, and particularly relates to an anode for a PEM water electrolysis cell, and a preparation method and application thereof. Background Following the necessary trend of the rapid development of low carbon economy and global 'carbon neutralization', hydrogen energy sources with extremely low carbon emissions are expected to replace fossil fuels to become one of the most important energy storage substances in the future. Hydrogen is a clean and green energy carrier, has higher specific heat capacity, and is suitable for storing intermittent renewable energy. In recent years, water electrolysis has become an attractive and rapidly growing method of producing hydrogen because the only byproduct is harmless oxygen. The method for preparing hydrogen by electrolyzing water in a comparatively environment-friendly way has a comparatively great prospect. Currently, hydrogen production facilities are Alkaline Water Electrolysers (AWE) and Proton Exchange Membrane Water Electrolysers (PEMWE). Conventional alkaline cells (AWE), which are relatively mature and inexpensive because they do not require a noble metal catalyst, use a porous membrane to separate hydrogen and oxygen using high concentration potassium hydroxide (KOH) as the electrolyte. AWE, while capable of producing hydrogen at lower cost, takes several hours to reach steady state under practical operating conditions, making it difficult to meet the intermittent renewable energy production needs. Fortunately, PEMWE reacts very rapidly to the high dynamic range, which is a desirable option for intermittent harvesting of renewable energy, producing completely green hydrogen. The "green hydrogen" produced by the Proton Exchange Membrane (PEM) electrolysis process of water is effective in fixing renewable energy sources (e.g., wind, solar, tidal, etc.) with time instability, which is expected to become an important way of "harvesting" renewable energy sources in the future. However, the use of PEM electrolysers is very costly, limiting their large-scale production and use in the field of electrolyzed water, due to the need to use noble metal catalysts based on iridium (Ir) or ruthenium (Ru) and pure titanium (Ti) anode electrode plates resistant to acid corrosion. The noble metal portion of the PEMWE stack includes a Porous Transport Layer (PTLs), bipolar Plates (BPs), and noble metal catalysts for Oxygen Evolution Reactions (OER) and Hydrogen Evolution Reactions (HER), which account for 82% of the total stack cost. Therefore, the need to effectively reduce the equipment and operating costs of PEM acid cells is urgent. Meanwhile, a layer of compact passivation film is easily generated between noble metal catalysts in the water electrolysis process of the Ti electrode, so that the internal resistance of the electrolytic cell is increased, and the conductivity of the electrode is increased in a manner of gold plating (Au) or gold plating (Pt) commonly used in engineering, so that the electrode cost is higher. In addition, the current common technical focus of PEMWEs is Catalyst Coated Membranes (CCM) in which an electrically conductive Ir-or Ru-based catalyst is coated on a proton exchange membrane. CCM is the core of PEMWE, which transmits protons, separates products and catalyzes HER and OER. In the current state-of-the-art PEMWE structures, the actual electrodes (anode and cathode) are physically pressed against the catalytic layer. However, this structure has a relatively high ohmic resistance and there is a risk of catalyst flaking. Researchers have conducted extensive research to develop non-noble metal catalysts for PEMWE and anode electrode plates. However, inexpensive transition metals have been found to undergo severe corrosion and dissolution in strongly acidic media (pH < 2) at high potential (> 1.6v vs. rhe). Furthermore, the use of inexpensive transition metal materials in PEMWE is limited by their low OER catalytic performance. Thus, there is an urgent need to develop inexpensive materials that are both durable and capable of catalyzing in strongly acidic media with high applied potentials. Stainless steel is used as a metal material with low cost and relative maturity, and has a great deal of application in a strong alkaline water electrolysis device because the stainless steel has good corrosion resistance under near neutral or alkaline conditions and a surface passivation layer of the stainless steel has certain catalytic capability. Currently, commercial stainless steel is unstable in a strongly acidic environment of high external potential, and undergoes severe corrosion and dissolution in practical PEMWEs. Therefore, pure titanium having high corrosion resistance is applied as an electrode in most PEMWEs, greatly increasing the cost of the galvanic pile. Under strongly acidic anodic polarizatio