▎ 摘　　要

Pt-Bi/GNs (Etching) catalyst is synthesized by a facile reduction process followed by nitric acid etching. After etching, most of Bi species (mainly B2O3) in Pt-Bi/GNs (Etching) are removed, and unique hollow Pt-Bi nanopartilces are formed with its hollow size and wall thickness of 2.5 nm and 3.0 nm, respectively. The etching process in synthesizing Pt-Bi bimetallic catalysts contributes to a larger electrochemical active surface area (ECSA) for Pt-Bi/GNs (Ecthing) due to its inner hollow shape and its traces Bi covered on Pt active sites. Interestingly, the introduction of tiny amount of Bi makes Pt-Bi/GNs (Etching) exhibit much better electrocatalytic performances (with the mass activity of 2000 mA mg(-1)) for methanol oxidation than the commercial PtRu/C catalyst, which can be interpreted in terms of its larger ECSA, bifunctional catalyzing mechanism and Pt moderate ed down-shift originating from the trace existence of Bi species. (c) 2018 Elsevier Ltd. All rights reserved.