Golden Single-Atom Alloys Selectively Boosting Oxygen Reduction and Methanol Oxidation.

Abstract

Engineering electrocatalysts at a single-atomic site can enable unprecedented atomic utilization and catalytic activity, yet it remains challenging in multimetallic active centers to simultaneously achieve high catalytic selectivity and stability. Herein, the atomic design and control of golden single-atom alloys (PdAu₁ and PtAu₁ SAAs) based on fully ordered PdBi and PtBi matrixes is presented, serving as highly selective, active, and stable cathode and anode electrocatalysts, respectively, to trigger direct methanol fuel cell (DMFC). The octahedral PdAu₁ SAA exhibits ultrahigh mass-activity of 5.37 A mg_{Pd + Au} ^-1 without noticeable decay for 12 0000 cycles toward oxygen reduction. While PdAu₁ SAA is inactive for methanol oxidation, PtAu₁ SAA exhibits an ultrahigh mass-activity of 28.59 A mg_{Pt + Au} ^-1. The selective electrocatalysts drive a practical DMFC with a high-power density of 155.0 mW cm^-2. Density functional theory calculations reveal the desired regulation of selectivity via reducing the energy barrier for potential-determining steps (PDS) of ^*OH to H₂O and ^*HCOO to CO₂. This work provides a general strategy to engineer multimetallic alloys at the atomic level, advancing the development of high-performance electrocatalysts.