Greatly Facilitated Two-Electron Electroreduction of Oxygen into Hydrogen Peroxide over TiO<sub>2</sub> by Mn Doping
Quanying Chen, Chaoqun Ma, Shihai Yan, Jie Liang, Kai Dong, Yonglan Luo, Qian Liu, Tingshuai Li, Yan Wang, Luchao Yue, Baozhan Zheng, Yang Liu, Shuyan Gao, Zhenju Jiang, Wei Li, Xuping Sun
Abstract
Ambient electrochemical oxygen reduction into valuable hydrogen peroxide (H2O2) via a selective two-electron (2e–) pathway is regarded as a sustainable alternative to the industrial anthraquinone process, but it requires advanced electrocatalysts with high activity and selectivity. In this study, we report that Mn-doped TiO2 behaves as an efficient electrocatalyst toward highly selective H2O2 synthesis. This catalyst exhibits markedly enhanced 2e– oxygen reduction reaction performance with a low onset potential of 0.78 V and a high H2O2 selectivity of 92.7%, much superior to the pristine TiO2 (0.64 V, 62.2%). Additionally, it demonstrates a much improved H2O2 yield of up to 205 ppm h–1 with good stability during bulk electrolysis in an H-cell device. The significantly boosted catalytic performance is ascribed to the lattice distortion of Mn-doped TiO2 with a large amount of oxygen vacancies and Ti3+. Density functional theory calculations reveal that Mn dopant improves the electrical conductivity and reduces ΔG*OOH of pristine TiO2, thus giving rise to a highly efficient H2O2 production process.