Bimetallic Ag-Cu nanosheets assembled flower-like structure for oxygen reduction reaction

Abstract

Fabricating low-cost and Pt-free fuel cell catalysts towards highly active and durable oxygen-reduction reaction catalysis remains a great challenge. Herein, we synthesize a bimetallic Ag–Cu nanosheets assembled flower-like structure by our developed cyclic scanning electrodeposition (CSE) method. The formation mechanism of this structure is investigated systematically, where Cu2+ can affect oxidative etching during the formation process. The prepared bimetallic nanostructure is studied for kinetics towards oxygen reduction reaction (ORR) in alkaline media. The electrochemical test results indicate that the ORR catalytic ability of bimetallic Ag–Cu nanostructure is competitive with Pt/C-20%, better than Pt disk, and far superior to the pure Ag nanostructure. The electrons transfer number (n) is close to four, which is further proved by scanning electrochemical microscope (SECM) experiments. Density functional theory (DFT) calculations reveal that the high ORR activity is attributable to the widely distributed Ag–Cu steps, which is formed by decorating Cu atoms on the Ag nanosheets.