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US-12626930-B2 - Electrochemical treatment of electrodes comprising bimetallic and trimetallic catalysts

US12626930B2US 12626930 B2US12626930 B2US 12626930B2US-12626930-B2

Abstract

Aspects of the present disclosure generally relate to processes for forming electrodes comprising bimetallic catalysts and to processes for forming electrodes comprising trimetallic catalysts. In an aspect, a process for making an electrode comprising carbon-supported metal alloy nanoparticles is provided. The process includes applying a plurality of first voltage cycles to an initial electrode, the initial electrode including metal alloy nanoparticles that includes platinum and one or more Group 8-11 metals, the one or more Group 8-11 metals free of Pt; and a carbon source. The process further includes applying a plurality of second voltage cycles to form a final electrode, the metal alloy nanoparticles of the final electrode having an oxygen reduction reaction (ORR) mass activity that is greater than the ORR mass activity of the initial electrode.

Inventors

  • Haibin Wu
  • Shutang CHEN
  • Gugang CHEN

Assignees

  • HONDA MOTOR CO., LTD.

Dates

Publication Date
20260512
Application Date
20230809

Claims (20)

  1. 1 . A process for making an electrode comprising carbon-supported metal alloy nanoparticles, the process comprising: applying a plurality of first voltage cycles from about 0 V to about +1.1 V to an initial electrode to form a resultant electrode, the initial electrode comprising: metal alloy nanoparticles comprising platinum and one or more Group 8-11 metals, the one or more Group 8-11 metals free of Pt; and a carbon source; and then applying to the resultant electrode a plurality of second voltage cycles from an initial potential ranging from about-0.2 V to about 0 V to a final potential of at least +1.2 V to form a final electrode, the metal alloy nanoparticles of the final electrode having an oxygen reduction reaction (ORR) mass activity that is greater than the ORR mass activity of the initial electrode.
  2. 2 . The process of claim 1 , wherein the ORR mass activity of the final electrode is about 20% or more than the ORR mass activity of the initial electrode.
  3. 3 . The process of claim 1 , wherein the plurality of first voltage cycles comprises: from about 10 to about 50 first voltage cycles; and each first voltage cycle comprises: increasing the voltage from about 0 V to about +1.1 V at a scan rate of about 10 mV/s to about 500 mV/s; and decreasing the voltage from about +1.1 V to about 0 V at a scan rate of about 10 mV/s to about 500 mV/s.
  4. 4 . The process of claim 1 , wherein the plurality of second voltage cycles comprises: from about 20 to about 150 second voltage cycles; and each second voltage cycle comprises: increasing the voltage from an initial potential ranging from about-0.2 V to about 0 V to a final potential ranging from about +1.2 to about +1.5 V at a scan rate of about 10 mV/s to about 500 mV/s; and decreasing the voltage from the initial potential to the final potential at a scan rate of about 10 mV/s to about 500 mV/s.
  5. 5 . The process of claim 1 , wherein each second voltage cycle comprises: increasing the voltage from an initial potential ranging from about-0.2 V to about 0 V to a final potential ranging from about +1.2 to about +1.3 V at a scan rate of about 10 mV/s to about 500 mV/s; and decreasing the voltage from the initial potential to the final potential at a scan rate of about 10 mV/s to about 500 mV/s.
  6. 6 . The process of claim 1 , wherein the one or more Group 8-11 metals comprises Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Cu, Ag, Au, or combinations thereof.
  7. 7 . The process of claim 1 , wherein the one or more Group 8-11 metals comprises Co, Ni, Fe, Cu, or combinations thereof.
  8. 8 . The process of claim 1 , wherein: an amount of metal alloy nanoparticles present in the initial electrode is from about 10 wt % to about 80 wt % based on a total amount of the metal alloy nanoparticles and the carbon source, the total amount not to exceed 100 wt %; and an amount of carbon source present in the initial electrode is from about 20 wt % to about 90 wt % based on the total amount of the metal alloy nanoparticles and the carbon source.
  9. 9 . The process of claim 1 , wherein: an amount of metal alloy nanoparticles present in the initial electrode is from about 20 wt % to about 60 wt % based on a total amount of the metal alloy nanoparticles and the carbon source, the total amount not to exceed 100 wt %; and an amount of carbon source present in the initial electrode is from about 40 wt % to about 80 wt % based on the total amount of the metal alloy nanoparticles and the carbon source.
  10. 10 . The process of claim 1 , wherein the metal alloy nanoparticles comprises Pt and Cu.
  11. 11 . The process of claim 10 , wherein the metal alloy nanoparticles further comprises Ni.
  12. 12 . A process for improving an oxygen reduction reaction (ORR) mass activity of a carbon supported catalyst, the process comprising: exposing an initial electrode comprising a carbon supported catalyst to a plurality of first voltage cycles to form a resultant electrode, comprising: (a) ramping the voltage from about 0 V to about +1.1 V; (b) ramping the voltage from about +1.1 V to about 0 V; and (c) repeating (a) and (b) at least 10 times; and then exposing the resultant electrode to a plurality of second voltage cycles to form a final electrode, comprising: (d) ramping the voltage from an initial potential ranging from about-0.2 V to about 0 V to a final potential ranging from about +1.2 V to about +1.5 V; (e) ramping the voltage from the final potential to the initial potential; and (f) repeating (d) and (e) at least 20 times, wherein the carbon supported catalyst comprises metal alloy nanoparticles and a carbon source, the metal alloy nanoparticles comprising Pt and one or more Group 8-11 metals, the one or more Group 8-11 metals free of Pt; and wherein the final electrode has an oxygen reduction reaction mass activity that is at least 20% more than the ORR mass activity of the initial electrode.
  13. 13 . The process of claim 12 , wherein the final potential of the plurality of second voltage cycles is from about +1.2 V to about +1.3 V.
  14. 14 . The process of claim 12 , wherein the final potential of the plurality of second voltage cycles is at least about +1.3 V.
  15. 15 . The process of claim 12 , wherein (f) comprises repeating (d) and (e) at least 40 times at a sweep rate of about 10 mV/s to about 100 mV/s.
  16. 16 . The process of claim 12 , wherein: the one or more Group 8-11 metals comprises Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Cu, Ag, Au, or combinations thereof; and an amount of metal alloy nanoparticles present in the initial electrode is from about 10 wt % to about 80 wt % based on a total amount of the metal alloy nanoparticles and the carbon source, the total amount not to exceed 100 wt %.
  17. 17 . The process of claim 12 , wherein the one or more Group 8-11 metals is selected from the group consisting of Co, Ni, Fe, Cu, and combinations thereof.
  18. 18 . A process for treating an electrode, comprising: (a) performing a cycle of sweeping a first potential continuously at least 10 times in cyclic voltammetry on an initial electrode comprising a carbon supported catalyst, wherein the first potential comprises a range of a first initial potential to a first final potential, the first initial potential ranging from about 0 V to about +0.2 V, the first final potential ranging from about +0.9 V to about +1.1 V to form a resultant electrode; and then (b) performing a cycle of sweeping a second potential continuously at least 20 times in cyclic voltammetry on the resultant electrode to form a final electrode, wherein the second potential comprises a range of a second initial potential to a second final potential, the second initial potential ranging from about-0.2 V to about 0 V, the second final potential ranging from about +1.2 V to about +1.5 V, the carbon supported catalyst comprising bimetallic alloy nanoparticles, trimetallic alloy nanoparticles, or combinations thereof, the bimetallic alloy nanoparticles and the trimetallic alloy nanoparticles comprising platinum and at least one Group 8-11 metal selected from the group consisting of Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Cu, Ag, Au, and combinations thereof.
  19. 19 . The process of claim 18 , wherein (b) is performed for 40 times to 60 times and at a sweep rate of about 10 mV/s to about 100 mV/s.
  20. 20 . The process of claim 18 , wherein the catalyst comprises Pt and Ni.

Description

FIELD Aspects of the present disclosure generally relate to processes for forming electrodes comprising bimetallic catalysts and to processes for forming electrodes comprising trimetallic catalysts. BACKGROUND Platinum (Pt) and its alloys are widely used as fuel cell electrode materials due to their exceptional catalytic performance. However, the current catalytic performance of these materials does not yet meet the demands of large-scale industrial applications. While platinum-nickel (PtNi) systems demonstrate better activity compared to typical catalysts like pure platinum and platinum-cobalt (PtCo) alloy, their limited durability has become a bottleneck in employing them as fuel cell cathode electrode materials. Overall, conventional Pt catalysts and Pt alloy catalysts lack the durability and high activity required for widespread acceptance. With the rapid growth in market demand for fuel cell products, there is a need to develop durable, highly active catalysts. There is a need for new and improved processes for forming electrodes comprising bimetallic catalysts and trimetallic catalysts having, for example, improved performance. SUMMARY Aspects of the present disclosure generally relate to processes for forming electrodes comprising bimetallic catalysts and to processes for forming electrodes comprising trimetallic catalysts. The bimetallic catalysts and trimetallic catalysts can be in the form of nanoparticles. The nanoparticles can be supported on carbon. Unlike conventional technologies which utilize voltages lower than +1.1 V to prevent catalyst destruction, processes described herein can utilize a high-voltage treatment (for example, about +1.3 V or more) of the catalysts to, for example, form new reactive crystalline facets, increase its durability, increase its mass activity, reduce its overpotential, increase its voltage efficiency, or combinations thereof, among other enhancements. That is, processes described herein can improve catalyst performance. In an aspect, a process for making an electrode comprising carbon-supported metal alloy nanoparticles is provided. The process includes applying a plurality of first voltage cycles from about 0 V to about +1.1 V to an initial electrode, the initial electrode including metal alloy nanoparticles comprising platinum and one or more Group 8-11 metals, the one or more Group 8-11 metals free of Pt; and a carbon source. The process further includes applying a plurality of second voltage cycles from an initial potential ranging from about −0.2 V to about 0 V to a final potential of at least +1.2 V to form a final electrode, the metal alloy nanoparticles of the final electrode having an oxygen reduction reaction (ORR) mass activity that is greater than the ORR mass activity of the initial electrode. In another aspect, a process for improving an oxygen reduction reaction (ORR) mass activity of a carbon supported catalyst is provided. The process includes exposing an initial electrode comprising a carbon supported catalyst to a plurality of first voltage cycles comprising: (a) ramping the voltage from about 0 V to about +1.1 V; (b) ramping the voltage from about +1.1 V to about 0 V; and (c) repeating (a) and (b) at least 10 times. The process further includes exposing the resultant electrode to a plurality of second voltage cycles to form a final electrode, comprising: (d) ramping the voltage from an initial potential ranging from about −0.2 V to about 0 V to a final potential ranging from about +1.2 V to about +1.5 V; (e) ramping the voltage from the final potential to the initial potential; and (f) repeating (d) and (e) at least 20 times, wherein the carbon supported catalyst comprises metal alloy nanoparticles and a carbon source, the metal alloy nanoparticles comprising Pt and one or more Group 8-11 metals, the one or more Group 8-11 metals free of Pt; and wherein the final electrode has an oxygen reduction reaction mass activity that is at least 20% more than the ORR mass activity of the initial electrode. In another aspect, a process for treating an electrode is provided. The process includes (a) performing a cycle of sweeping a first potential continuously at least 10 times in cyclic voltammetry on an initial electrode comprising a carbon supported catalyst, wherein the first potential comprises a range of a first initial potential to a first final potential, the first initial potential ranging from about 0 V to about +0.2 V, the first final potential ranging from about +0.9 V to about +1.1 V; and then (b) performing a cycle of sweeping a second potential continuously at least 20 times in cyclic voltammetry on the resultant electrode to form a final electrode, wherein the second potential comprises a range of a second initial potential to a second final potential, the second initial potential ranging from about −0.2 V to about 0 V, the second final potential ranging from about +1.2 V to about +1.5 V, the carbon supported catalyst comprises bimetallic