Highly Active and Renewable Catalytic Electrodes for Two-Electron Oxygen Reduction Reaction

This study has shown that antimony-doped tin oxide (ATO) works as a robust “renewable catalyst” for the electrochemical synthesis of hydrogen peroxide (H2O2) from water and oxygen. Antimony doping into SnO2 gives rise to remarkable electrocatalytic activity for two-electron oxygen reduction reaction (2e–-ORR) by water with a volcano-type relation between the activity and doping levels (xSb). Density functional theory simulations highlight the importance of an isolated Sb atom of ATO inducing the high activity and selectivity for 2e–-ORR due to the effects of O2 adsorption enhancement, decrease in the activation energy, and lowering the adsorptivity of H2O2. Electrolysis by a normal three-electrode cell using ATO (xSb = 10.2 mol %) at −0.22 V (vs reversible hydrogen electrode) stably and continuously produces H2O2 with a turnover frequency of 6.6 s–1. This remarkable activity can be maintained even after removing the surface layer of ATO by argon-ion sputtering.