▎ 摘　　要

Electrochemical oxygen reduction and methanol oxidation are two important reactions in the development of clean energy technology. Substantial progresses in the design of cheap, robust, and efficient catalysts are still required and remain a significant challenge. Here, we report a double pulse electrodeposition process, capable of controlling the density and the size of silver nanoparticle supported on graphene. We found that this catalyst afforded a current density of 5.5 mA cm(-2) at a low potential for ORR, comparing favourably with the state-of-the-art Pt/C catalyst. Additionally, we demonstrate that size and distribution effects are critical parameters for more efficient ORR and MOR catalysis. Our results suggest possibility for the development of effective and robust ORR and MOR electrocatalysts based on cheap silver metal and graphene and as replacements for the commercially available but expensive Pt/C catalysts. (C) 2017 Elsevier Ltd. All rights reserved.