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EP-4740252-A2 - IN SITU CATALYST SYNTHESIS, DEPOSITION AND UTILIZATION

EP4740252A2EP 4740252 A2EP4740252 A2EP 4740252A2EP-4740252-A2

Abstract

Disclosed herein is an electrolyte comprising H+ or OH- and precursors used to make a hydrogen evolution electrocatalyst, an oxygen evolution electrocatalyst, a bifunctional hydrogen/ oxygen evolution electrocatalyst, or any combination thereof for use in in situ catalyst synthesis, deposition and/or utilization.

Inventors

  • BARFOROUSH, Joseph, Mohammad
  • HIETALA, Kristen, Taylor
  • DAUGHERTY, Mark, Alan

Assignees

  • Avium LLC

Dates

Publication Date
20260513
Application Date
20240708

Claims (20)

  1. 1. A method for depositing electrocatalysts, the method comprising: introducing into an alkaline electrolyzer an electrocatalyst precursor, wherein the alkaline electrolyzer has an electrolyte comprising OH' and one or more electrodes or mixing an electrocatalyst precursor with an electrolyte comprising OH' and contacting the resulting mixture with one or more electrodes having a current applied thereto.
  2. 2. The method of claim 1, wherein a current is applied to the one or more electrodes during introduction of the electrocatalyst precursor.
  3. 3. The method of claim 1, wherein a current is applied to the one or more electrodes prior to and during introduction of the electrocatalyst precursor without interrupting application of the current to the one or more electrodes.
  4. 4. The method of claim 1, comprising mixing an electrocatalyst precursor with the electrolyte comprising OH' and contacting the resulting mixture with the one or more electrodes having a current applied thereto.
  5. 5. The method of claim 4, wherein the electrocatalyst precursor and the electrolyte are mixed in an alkaline electrolyzer comprising the one or more electrodes having the current applied thereto.
  6. 6. The method of claim 1, wherein the electrocatalyst precursor comprises a metal nitrate, a metal sulfate, a metal acetate, a metal chloride, a metal sulfamate, or any combination thereof.
  7. 7. The method of claim 1, wherein the electrocatalyst precursor comprises Fe, Ni, Co, Cr, Cu, or any combination thereof.
  8. 8. The method of claim 1, wherein the electrocatalyst precursor is in solution.
  9. 9. The method of claim 1, wherein the electrocatalyst precursor is an aqueous solution of Fe (III) nitrate, Ni (II) nitrate, Co (II) nitrate, Cr (III) nitrate, Cu (II) nitrate, Fe (II) chloride, Ni (II) chloride, Co (II) chloride, Ni (II) acetate, Co (II) acetate, Ni (II) sulfamate, Fe (II) sulfamate, Co (II) sulfamate, Ni (II) sulfate, Fe (III) sulfate, Cu (II) sulfate, Co (II) sulfate, Cr (III) sulfate, or any combination thereof.
  10. 10. The method of claim 1, wherein the electrocatalyst precursor comprises an enabling metal.
  11. 11. The method of claim 1, wherein the electrolyte comprises KOH or NaOH.
  12. 12. The method of claim 1, wherein the electrocatalyst precursor prepares an electrocatalyst selected from a hydrogen evolution catalyst, oxygen evolution electrocatalyst, bifunctional hydrogen/oxygen evolution electrocatalyst, or any combination thereof.
  13. 13. The method of claim 1, wherein the electrocatalyst is deposited simultaneously with a hydrogen evolution reaction or oxygen evolution reaction.
  14. 14. An alkaline electrolyzer comprising an electrode, an electrolyte comprising OH', and an electrocatalyst precursor.
  15. 15. The alkaline electrolyzer of claim 14, wherein the electrocatalyst precursor comprises a metal nitrate, a metal sulfate, a metal acetate, a metal chloride, a metal sulfamate, or any combination thereof.
  16. 16. The alkaline electrolyzer of claim 14, wherein the electrocatalyst precursor comprises Fe, Ni, Co, Cr, Cu, or any combination thereof.
  17. 17. The alkaline electrolyzer of claim 14, wherein the electrocatalyst precursor is in solution.
  18. 18. The alkaline electrolyzer of claim 14, wherein the electrocatalyst precursor is an aqueous solution of Fe (III) nitrate, Ni (II) nitrate, Co (II) nitrate, Cr (III) nitrate, Cu (II) nitrate, Fe (II) chloride, Ni (II) chloride, Co (II) chloride, Ni (II) acetate, Co (II) acetate, Ni (II) sulfamate, Fe (II) sulfamate, Co (II) sulfamate, Ni (II) sulfate, Fe (III) sulfate, Cu (II) sulfate, Co (II) sulfate, Cr (III) sulfate, or any combination thereof.
  19. 19. The alkaline electrolyzer of claim 14, wherein the electrocatalyst precursor comprises an enabling metal.
  20. 20. The alkaline electrolyzer of claim 19, wherein the enabling metal is Fe, Co, Cu, or any combination thereof.

Description

IN SITU CATALYST SYNTHESIS, DEPOSITION AND UTILIZATION CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims priority to U.S. Patent Application No. 63/525,273 filed July 6, 2023, the entire contents of which are hereby incorporated by reference. FIELD OF THE INVENTION The disclosed technology is generally directed to methods and systems for preparation and use of electrocatalysts. More particularly the technology is directed to methods and systems for maintaining high efficiency hydrogen production from water and for servicing an electrolyzer stack. BACKGROUND OF THE INVENTION The development of efficient, earth-abundant electrocatalysts for the water splitting reactions, i.e., the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is of great importance as the world switches to a carbon free economy. In an electrolyzer, the HER occurs on a cathode electrode while the OER occurs on an anode electrode. Earth-abundant catalysts that do not contain Platinum Group Metals (PGMs) are lower cost and have less supply chain risks than catalysts that use PGMs. Improvements in electrocatalysts that increase the efficiency of water splitting translate directly into lower hydrogen production costs which will accelerate the decarbonization of global energy systems. Traditionally, electrodes are coated with electrocatalysts prior to assembly of an electrolyzer stack, which consists of repeating cells comprising a cathode electrode and an anode electrode with a separator in between the anode and cathode and a bipolar plate between cells. Once integrated with the balance of plant for operation, the stack is typically non-serviceable and must eventually be replaced entirely due to decrease in efficiency over time. Typical stack replacement intervals for alkaline electrolyzers are in a range of 60,000 h to 100,000 h. The end of life for a stack is typically marked by a degradation in efficiency to below approximately 90% of the initial value. Replacement of stacks is a significant capital cost. Stack replacement also requires the electrolyzer to be shut down, disassembled, and reassembled. Therefore, methods and systems for maintaining high efficiency and for servicing a stack without needing to shut down, disassemble, or reassemble the stack or the electrolyzer are needed. BRIEF SUMMARY OF THE INVENTION Disclosed herein are methods, systems, and compositions for synthesizing electrocatalysts inside of an electrolyzer stack (in situ electrocatalyst synthesis) and for reactively depositing electrocatalysts on the electrodes inside of an electrolyzer stack (in situ reactive deposition). One aspect of the technology provides for a method for depositing electrocatalysts. The method may comprise introducing into an alkaline electrolyzer an electrocatalyst precursor, wherein the alkaline electrolyzer has an electrolyte comprising OH- and one or more electrodes. Suitably, a current is applied to the one or more electrodes during introduction of the electrocatalyst precursor solution. Additionally, or alternatively, wherein a current is applied to the one or more electrodes prior to and during introduction of the electrocatalyst precursor solution without interrupting application of the current to the one or more electrodes. Another aspect of the technology provides for a method for depositing electrocatalysts where the method comprises mixing an electrocatalyst precursor with an electrolyte comprising OH- and contacting the resulting mixture with one or more electrodes having a current applied thereto. Suitably, the electrocatalyst precursor and the electrolyte are mixed in an alkaline electrolyzer comprising the one or more electrodes having the current applied thereto. In the disclosed methods, the electrocatalyst precursor comprises a metal nitrate, a metal sulfate, a metal acetate, a metal chloride, a metal sulfamate, or any combination thereof. Suitably, the electrocatalyst precursor comprises Fe, Ni, Co, Cr, Cu, or any combination thereof. Exemplary electrocatalyst precursors include an aqueous solution of Fe (III) nitrate, Ni (II) nitrate, Co (II) nitrate, Cr (III) nitrate, Cu (II) nitrate, Fe (II) chloride, Ni (II) chloride, Co (II) chloride, Ni (II) acetate, Co (II) acetate, Ni (II) sulfamate, Fe (II) sulfamate, Co (II) sulfamate, Ni (II) sulfate, Fe (III) sulfate, Cu (II) sulfate, Co (II) sulfate, or Cr (III) sulfate, or any combination thereof. Additional aspects of the invention include alkaline electrolyzers, reactor systems, and compositions that may be used in the methods described herein. These and other aspects of the invention will be further described herein. BRIEF DESCRIPTION OF THE DRAWINGS Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically r