Silver-induced adsorption optimization of adjacent Co tetrahedral sites for enhanced oxygen reduction/evolution reaction

Abstract

Physical structure change of catalysts based on the electronic metal-support interaction (EMSI) effects is a prospective strategy to regulate the surface electronic structure of catalysts and further enhance their catalytic performance. To optimize the constrained intrinsic oxygen evolution reaction/oxygen reduction reaction (OER/ORR) activity of spinel MnCo2O4, we present a facile hydrothermal and photoreduction strategy to synthesize the Ag and MnCo2O4 supported on N-doped carbon nanotubes (Ag-MnCoO/NCNTs) with the EMSI effect. Ag-MnCoO/NCNTs as catalyst shows enhanced performance for OER (overpotential of 340 mV) and ORR (half-wave potential of 0.80 V). Furthermore, a zinc-air battery is assembled based on Ag-MnCoO/NCNTs cathode, which affords an open circuit potential of 1.49 V and favorable cycling performance for 200 h. Theoretical calculations illustrate the introduction of Ag reduces the charge density of the tetrahedral Co site along the direction of the dangling bonds and optimizes the adsorption of oxygen intermediates on tetrahedral Co, thus lowering the reaction activation energy and improving its oxygen catalytic activity. This work provides new insights to guide the fabrication of advanced oxygen electrocatalysts.