Manipulating oxygenate adsorption on N-doped carbon by coupling with CoSn alloy for bifunctional oxygen electrocatalyst

Abstract

Highly active bifunctional oxygen electrocatalysts accelerate the development of high-performance Zn-air battery, but suffer from the mismatched activities of oxygen evolution reaction (OER) and oxygen reduced reaction (ORR). Herein, highly integrated bifunctional oxygen electrocatalysts, cobalt-tin alloys coated by nitrogen doped carbon (CoSn@NC) are prepared by MOFs-derived method. In this hybrid catalyst, the binary CoSn nanoalloys mainly contribute to highly active OER process while the Co (or Sn)−N−C serves as ORR active sites. Rational interaction between CoSn and NC donates more rapid reaction kinetics than Pt/C (ORR) and IrO2 (OER). Such CoSn@NC holds a promise as air-cathode electrocatalyst in Zn-air battery, superior to Pt/C + IrO2 catalyst. First-principles calculations predict that CoSn alloys can upgrade charge redistribution on NC and promote the transfer to reactants, thus optimizing the adsorption strength of oxygen-containing intermediates to boost the overall reactivity. The tuning of oxygenate adsorption by interactions between alloy and heteroatom-doped carbon can guide the design of bifunctional oxygen electrocatalysts.