The operation active sites of O2 reduction to H2O2 over ZnO

The two-electron oxygen reduction reaction (2e(-) ORR) in neutral media is a promising method to achieve hydrogen peroxide (H2O2) from oxygen (O-2) directly in a sustainable way. Here, we show an ideal ZnO@ZnO2 electrocatalyst for efficient O-2 reduction to H2O2 in a neutral medium. The in situ growth of ZnO2 on ZnO forms the operation active sites, namely the heterogeneous interface between tetrahedral ZnO and octahedral ZnO2, weakening the binding energies of both OOH* and O*. In a 0.1 M K2SO4 electrolyte, ZnO@ZnO2 shows a H2O2 selectivity of nearly 100.0% via the ORR, while it can convert O-2 to H2O2 with a production rate of 5.47 mol g(cat)(-1) h(-1) at 0.1 V vs. RHE and a Faraday efficiency (FE) of & SIM;95.5%, tested using a gas diffusion electrode device. The pulse voltage-induced current (PVC) was utilized in conjunction with a number of in situ characterization techniques and electrochemical studies to disclose the transformation of the ZnO surface and the production process of operational catalytic active sites on ZnO.

Automated summary

We demonstrate an ideal ZnO@ZnO2 electrocatalyst for efficient oxygen reduction to hydrogen peroxide in a neutral medium. The in situ growth of ZnO2 on ZnO forms heterogeneous interfaces, weakening the binding energies of OOH* and O*. In a 0.1 M K2SO4 electrolyte, ZnO@ZnO2 exhibits nearly 100.0% selectivity for H2O2 production and a production rate of 5.47 mol g(cat)(-1) h(-1) at 0.1 V vs. RHE, with a Faraday efficiency of approximately 95.5%.