Electrochemical-leaching route for the size-controllable synthesis of copper-based oxygen reduction reaction catalysts: From nanoparticles to atomic clusters and single atoms

Size-controllable synthesis of non-noble metal particles ranging from nanometer to subnanometer and atomic level is of great significance for demonstrating the size effects of metallic catalysts towards oxygen reduction reaction (ORR) catalysis. Herein, we propose an electrochemical leaching strategy for the top-down synthesis of Cu nanoparticles (NPs), atomic clusters (ACs) and single atoms (SAs) on sulfur-doped reduced graphene oxide (SrGO). Within this strategy, Cu NPs (about 8 nm) were electrodeposited and subsequently controllably downsized to ACs (about 2 nm) and SAs (