Boosting the oxygen reduction activity of silver nanoclusters via selective exposure of solvent-coordinated sites

Abstract

Metal nanoclusters (MNCs) have gained extensive research interest in catalysis. However, addressing the spatial resistance induced by surface ligands and the high aggregation tendency of MNCs is a challenge during the catalytic process. In this work, we present a rational strategy to expose the metal sites occupied by weak coordination, thereby activating the catalytic centers. In particular, Ag12 nanoclusters containing six acetonitrile auxiliary ligands were prepared (AgNCs) and solvent molecules were removed via mild photo-reduction. Moreover, graphene oxide (GO) was introduced as a support to stabilize the AgNCs for further control of the geometrical structure while modulating the coordination and electronic environment. According to density functional theory (DFT) calculations, compared with the bulk AgNCs, the free Ag atoms without CH₃CN enhanced the interactions with the intermediates of *OOH, pointing to promising catalytic ability for oxygen reduction reactions (ORRs). The activated AgNCs@GO catalyst exhibited a half-wave potential of 915 mV vs. RHE and a low Tafel slope of 45 mV dec⁻¹ for the ORR. In this work, a rational method was developed to boost the catalytic activity of MNCs towards electrochemical scenarios, demonstrating the promising potential of MNC-based materials for electrocatalysis.