Tailoring Oxygen Reduction Activity of Porous Au−Ag Bimetallic Nanoparticles through Composition and Facet Engineering

Abstract

In this work, the electrocatalytic oxygen reduction reaction (ORR) performance of bimetallic Au−Ag nanoparticles (NPs) is effectively improved via a triple modification strategy involving nanoporosity introduction, compositional regulation, and facet engineering. Porous bimetallic Au−Ag NPs are first fabricated through a galvanic replacement reaction, where the Au/Ag molar ratio is modulated to systematically explore the composition-dependent ORR electrocatalytic behavior. The optimal Au content for superior ORR electrocatalytic performance is determined to be approximately 40 at %, yielding the optimized Au40Ag60 alloy. The remarkable ORR enhancement is primarily attributed to the intrinsic bimetallic synergy between Au and Ag atoms, as well as the abundant catalytic active sites endowed by the high specific surface area of porous Au40Ag60 NPs. To further promote their electrocatalytic activity, surfactant-assisted facet engineering is employed to enrich the NP surface with high-density {100} facets and step terrace structures. The significantly boosted ORR performance is further verified by first-principles density functional theory (DFT) calculations. This work proposes a feasible strategy integrating compositional optimization and surface facet tailoring via a bottom-up synthetic route, which provides a reliable reference for the performance modulation of bimetallic ORR electrocatalysts.