Indium oxide with oxygen vacancies boosts O₂ adsorption and activation for electrocatalytic H₂O₂ production

Oxygen reduction reaction via the two-electron pathway (2e^- ORR) offers a sustainable opportunity for hydrogen peroxide (H₂O₂) production, but suffers from low selectivity. In this work, indium oxide with oxygen vacancies (In₂O_3-) exhibits a H₂O₂ selectivity close to 98% at 0.6 V vs. RHE. Further, a Faradaic efficiency (FE) of around 95% at 0.4-0.6 V vs. RHE and a H₂O₂ productivity of 3.7 mol g_catalyst^-1 h^-1 are reached in a flow cell. In situ Raman spectra indicate that In₂O_3- promotes the adsorption and activation of O₂ and stabilizes oxygen intermediates. This work provides an insight into improving H₂O₂ selectivity for 2e^- ORR catalysts.