Electrochemical-reduction-assisted assembly of ternary Ag nanoparticles/polyoxometalate/graphene nanohybrids and their activity in the electrocatalysis of oxygen reduction

Abstract

The green, facile, electrochemical-reduction-assisted assembly of ternary Ag nanoparticles (NPs)@polyoxometalate (POM)/reduced graphene oxide (rGO) is reported. The POM served as an electrocatalyst and bridging molecule. Characterization using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman and FT-IR spectroscopy analysis, etc., was performed and verified the structure of the prepared nanohybrids of Ag NPs@POM/rGO. The density and size of the Ag NPs on the rGO can be simply tuned by changing the concentration of Ag⁺. Most importantly, it is interesting to find that the ternary Ag NPs@POM/rGO nanohybrids showed much better electrocatalytic activities towards the oxygen reduction reaction than binary Ag NPs@POM and POM/rGO nanohybrids, and a direct four-electron transfer pathway was observed because of the synergistic effect of the Ag NPs and rGO. The electrocatalytic performance of Ag NPs@POM/rGO depended on the loading amount of Ag NPs, and 30% Ag NPs@POM/rGO showed the best electrocatalytic performance.