Balancing Activity and Stability in a Ternary Au‐Pd/Fe Electrocatalyst for ORR with High Surface Coverages of Au

Abstract

Sluggish kinetics of the oxygen reduction reaction (ORR) and low durability of ORR catalysts in polymer electrolyte membrane fuel cells (PEM‐FCs) requires a continued search for advanced catalysts. Bimetallic catalysts demonstrate enhanced kinetics due to the optimized electronic properties from alloying but can suffer from poor stability of the active metals. Herein we report our findings that while bulk gold is catalytically inactive, high coverages (> 0.6 monolayer) of Au deposited on a Pd3Fe(111) surface were highly active and stable. These properties of Au‐modified Pd3Fe(111) surfaces are associated with initial formation of 2D nanostructures at step edges and the transition of 2D to 3D nanostructures under reaction conditions. The balancing of activity and stability in this ternary Au‐Pd/Fe electrocatalyst provides a potential candidate for non‐Pt, highly stable ORR catalysts. Similar nanostructures and conditions may be able to activate gold for use in other electrocatalytic reactions.

S-doped AuPd aerogels as high efficiency catalysts for the oxygen reduction reaction by balancing the ratio between bridging S22− and apical S2− ligands

“…This excellent long-term stability for the AuPd-S B67A33 aerogels could be attributed to the formation of alloys AuPd, Pd 2.8 S and PdS 2 on their surface, which enhance the resistance of their surfaces against oxidation by inhibiting the formation of Pd-O oxide species at high potential. [74][75][76] In brief, the superior electrocatalytic activity (E 1/2 ¼ 0.970 V, 2.60 A mg Pd À1 and 2.67 mA cm À2 at 0.9 V vs. RHE) towards the ORR of AuPd-S B67A33 aerogels can be ascribed to the following aspects: (1) the proper downshi of the d-band center of Pd achieved by balancing the ratio of S 2 2À to S 2À ligands.…”

“…This excellent long-term stability for the AuPd–S B67A33 aerogels could be attributed to the formation of alloys AuPd, Pd 2.8 S and PdS 2 on their surface, which enhance the resistance of their surfaces against oxidation by inhibiting the formation of Pd–O oxide species at high potential. 74–76…”

Novel palladium-based nanomaterials for multifunctional ORR/OER/HER electrocatalysis

“…35 To solve the problems existing in binary alloy catalysts, researchers have started to try to add more components in the alloy compound, like in ternary alloys. Xiaofang Yang et al 18 used inactive bulk gold to cover the surface of the Pd–Fe alloy catalyst and the results showed a large improvement of stability (Fig. 1a).…”

“…Reproduced with permission. 18 Copyright 2019, John Wiley and Sons. (b) TEM image of 20 wt% Pd 3 Fe/C.…”

“…The catalyst fabrication cost is also related to the loading mass of noble metals, and researchers utilized different strategies to address the cost issue like alloying with non-noble metals. 13,[18][19][20] These comparable properties of Pd make it attractive for highperformance electrocatalysis. Based on Pd, researchers can design different materials to meet different requirements for electrocatalytic functions.…”