The operation active sites of O2 reduction to H2O2 over ZnO

The two-electron oxygen reduction reaction (2e- ORR) is a promising method to achieve hydrogen peroxide (H2O2) from oxygen (O2) directly in a sustainable way. Here, we show an ideal ZnO@ZnO2 electrocatalyst for efficient O2 reduction to H2O2 in a neutral medium. 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% at 0.1 V vs. RHE, while it can convert O2 to H2O2 with a production rate of 5.47 mol gext-1 h-1 at 0.1 V vs. RHE and a Faraday efficiency (FE) of ~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 theories to disclose the transformation of the ZnO surface and the production process of operational catalytic active sites on ZnO.

Authors: Yunjie Zhou, Liang Xu, Jie Wu, Wenxiang Zhu, Tiwei He, Hao Yang, Hui Huang, Tao Cheng, Yang Liu, Zhenhui Kang

Journal: Energy Environ. Sci., 2023, 16, 3526-3533

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