Pony-Size Silver-Copper and Silver-Iron Alloy Nanoparticles Confined in N-Free Mesoporous Carbon for Efficient Oxygen Electroreduction

Abstract

Silver-copper (AgCu/tri-OMC) and silver-iron (AgFe/tri-OMC) alloy nanoparticles supported on resols-derived ordered mesoporous carbon were prepared by an impregnation-reduction method. The confinement effect of mesopore channels resulted into the well-dispersed AgCu and AgFe nanoparticles (<10 nm) which were uniformly embedded in the frameworks of nitrogen-free carbons with over 700 m2/g specific surface area. The AgCu/tri-OMC and AgFe/tri-OMC were demonstrated to be the efficient electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. The AgCu/tri-OMC especially exhibited the eminent electrocatalytic performance with onset potential of 1.00 VRHE and half-wave potential of 0.82 VRHE for ORR, intrinsic long-time durability and excellent methanol tolerance, superior to AgFe/tri-OMC catalysts, Pt/C (20 wt%) and other Ag-based alloy catalysts reported in literature. The higher activity of AgCu/tri-OMC originates in the optimum balance between the O-O bond split and desorption of the oxygenated intermediates controlled by energy of the d-band center of Ag in the ORR. The prepared catalytic materials may have broad application prospects and more practical value.