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KR-20260064893-A - Ru electrocatalyst for alkaline-based Hydrogen evolution reaction and preparation method thereof

KR20260064893AKR 20260064893 AKR20260064893 AKR 20260064893AKR-20260064893-A

Abstract

A hydrogen generation reaction catalyst for alkaline water electrolysis according to an embodiment of the present invention comprises: a forward transition metal oxide support; and a catalyst layer having a thickness of 1 nm to 20 nm formed on the surface of the support and containing Ru, wherein the forward transition metal oxide support may include any one of Ti, Ta, and Zr. In this case, the forward transition metal oxide support may have a forward transition metal oxide support lattice-limited structure that provides electrons to Ru through metal-support interaction. Accordingly, according to the present invention, electrode degradation can be prevented in a simple and inexpensive manner compared to conventional catalysts, thereby extending the electrode lifespan while increasing the efficiency of the electrolytic cell.

Inventors

  • 김용태
  • 정상문

Assignees

  • 포항공과대학교 산학협력단

Dates

Publication Date
20260508
Application Date
20241030

Claims (15)

  1. A leading transition metal oxide support; and a catalyst layer formed on the surface of the support and having a thickness of 1 nm to 20 nm and containing Ru; comprising The above-mentioned leading transition metal oxide support is a hydrogen generation reaction catalyst comprising any one of Sc, Ti, V, Cr, Mn, Zr, Nb, Mo, Lu, Hf, and Ta.
  2. In paragraph 1, The above-mentioned forward transition metal oxide support is a hydrogen evolution reaction catalyst having a forward transition metal oxide support lattice-limited structure that provides electrons to Ru through metal-support interactions.
  3. In paragraph 1, A hydrogen generation reaction catalyst having a Ru catalyst layer with a thickness of 5 nm to 20 nm.
  4. In paragraph 1, A hydrogen generation reaction catalyst having a Ru catalyst layer with a thickness of 10 nm.
  5. In paragraph 1, The above-mentioned leading transition metal oxide support is a hydrogen generation reaction catalyst containing Ti.
  6. In paragraph 1, A hydrogen generation reaction catalyst characterized by having a reverse current stability coefficient (RCSF) of 0.5 or higher.
  7. An alkaline water electrolysis cell comprising: an anode; a cathode; a separator located between the anode and the cathode; and a current collector connected to each of the anode and the cathode, wherein the cathode comprises a hydrogen generation reaction catalyst according to any one of claims 1 to 6.
  8. A step of oxidizing the surface of a pellet of Ti, Ta, or Zr to form a front transition metal oxide support; A step of depositing a Ru catalyst layer with a thickness of 1 nm to 20 nm on the surface of the oxide support; and A method for manufacturing a hydrogen generation reaction catalyst comprising the step of heat-treating an oxide support on which the above Ru catalyst layer is deposited.
  9. In paragraph 8, The step of forming the oxide support above is, A step of grinding the above pellets; A step of annealing the above-mentioned polished pellet at 400 to 600°C in an Ar-5% H₂ atmosphere for at least 300 seconds; and a step of oxidizing the above-mentioned annealed pellet by cyclic voltammetry (CV); comprising Method for manufacturing a hydrogen generation reaction catalyst.
  10. In paragraph 8, A method for preparing a hydrogen generation reaction catalyst, wherein the above heat treatment step is performed at 400 to 600°C for 300 seconds or more in an Ar-5% H₂ atmosphere.
  11. In paragraph 8, A method for preparing a hydrogen generation reaction catalyst, wherein the above-mentioned forward transition metal oxide support has a forward transition metal oxide support lattice-limited structure that provides electrons to Ru through metal-support interaction.
  12. In paragraph 8, A method for manufacturing a hydrogen generation reaction catalyst having a thickness of 5 nm to 20 nm of the Ru catalyst layer.
  13. In paragraph 8, A method for manufacturing a hydrogen generation reaction catalyst having a Ru catalyst layer with a thickness of 10 nm.
  14. In paragraph 8, A method for preparing a hydrogen generation reaction catalyst, wherein the above-mentioned leading transition metal oxide support comprises Ti.
  15. In paragraph 8, A method for manufacturing a hydrogen generation reaction catalyst having a reverse current stability coefficient (RCSF) of 0.5 or higher.

Description

Ruthenium electrocatalyst for alkaline-based hydrogen evolution reaction and preparation method thereof The present invention relates to a catalyst for a hydrogen generation reaction in alkaline water electrolysis and a method for manufacturing the same, and more specifically, to a catalyst for an alkaline hydrogen generation reaction and a method for manufacturing the same in which the lifespan and HER performance are significantly improved by using Ru and an advanced transition metal oxide as a cathode catalyst. Improving the slow kinetics of the hydrogen evolution reaction (HER) in alkaline environments is critical for minimizing the high overpotential and associated energy losses in water-alkali and chlor-alkali electrolytic cells. To this end, the development of highly active, durable, and cost-effective electrocatalysts is required to enhance the overall efficiency of the device. While platinum (Pt) and Pt-based catalysts are representative HER electrocatalysts, their high cost ($33.0g, as of July 2024) and scarcity can hinder large-scale commercialization. Ruthenium (Ru) is one-third the cost of platinum ($12.8.0g, as of July 2024) but offers adequate hydrogen bonding strength, making it a more economical choice for large-scale applications. In particular, Ru's excellent water dissociation ability can increase its potential as an HER electrocatalyst to replace Pt under alkaline conditions. Conventionally, the durability of Ru-based HER electrocatalysts was not a major concern because they could maintain stability for over 1,000 hours under steady-state conditions with minimal performance degradation. However, under actual operating conditions, the durability of Ru-based cathodes can be compromised. In particular, cathode catalysts may face stability issues due to dissolution if exposed to "reverse current (RC)" phenomena during the start/stop (SU/SD) of the electrolytic cell stack. Such SU/SD situations can inevitably occur due to the intermittent power supply of renewable energy sources or the termination of necessary maintenance. Reverse current occurs during the operation of an electrolytic cell stack due to the potential difference between the anode and cathode, the electron path through the anode plate, and the ion path through the manifold. Under normal operating conditions, the cathode and anode sites are located in the reducing material (composed of H₂ and a reducing species catalyst) and the oxidizing material (composed of O₂ and an oxidizing species catalyst), respectively. When the operation of the electrolytic cell stack is stopped, both the reducing species at the cathode and the oxidizing species at the anode are electrically connected through the bipolar plate. In this case, the manifold for circulating the electrolyte in the AWE system unintentionally forms an ion path, which completes a "galvanic cell" and initiates a spontaneous self-discharge process. During this process, current flows in the opposite direction to that of normal electrolysis (reverse current phenomenon), which can lead to oxidation and reduction at the cathode and anode, respectively. The reverse current continues to flow until potential equilibrium is established between the two electrodes, which can ultimately cause performance degradation of the electrolytic cell stack. Oxidation of the cathode due to the RC phenomenon can lead to the dissolution or passivation of the catalyst, resulting in a severe degradation of catalytic performance. In particular, Ru-based HER electrocatalysts can decompose due to dissolution in the high potential region under alkaline conditions. Theoretically, metallic Ru can be further oxidized to unstable Ru(VI) at 0.7 V vs RHE (Ru + 6OH - = Ru₂O₃ + 3H₂O + 6e - , Ru₂O₃ + 2OH - = 2RuO₂ + 2H₂O + 2e -), and Ru at 1.0 V vs RHE ( RuO₂ + 4OH - = RuO₄₂ - + 2H₂O + 4e - ). The dissolution of Ru during reverse current causes a loss of Ru's electrochemical surface area (ECSA), leading to a decrease in catalytic activity for the HER. FIG. 1 is a drawing showing an AWE cell according to one embodiment of the present invention. FIG. 2a shows the obtained HER polarization curves for TiO x with a ruthenium thin film according to one embodiment of the present invention and glassy carbon (GC) with a ruthenium thin film as a comparative example, and FIG. 2b shows Tafel plots for Ru 10 TiO x and conventional Ru 10 GC after 20 RC cycles according to one embodiment of the present invention. FIG. 2c shows a comparison of RCSF and RCAF values for Ru/GC and Ru/TiO x after 20 RC cycles for TiO x with a ruthenium thin film according to one embodiment of the present invention and glassy carbon (GC) with a ruthenium thin film as a comparative example. FIG. 2d shows the amount of Ru dissolved according to the thickness of the Ru thin film according to one embodiment of the present invention. FIG. 3 is a schematic diagram showing the reverse current resistance mechanism of a Ru/TiO x electrocatalyst architecture accor