title: Stable Aqueous Photoelectrochemical CO2 Reduction by a Cu2 O Dark Cathode with Improved Selectivity for Carbonaceous Products.
abstract: Photocatalytic reduction of CO2 to produce fuels is a promising way to reduce CO2 emission and address the energy crisis. However, the H2 evolution reaction competes with CO2 photoreduction, which would lower the overall selectivity for carbonaceous products. Cu2 O has emerged as a promising material for suppressing the H2 evolution. However, it suffers from poor stability, which is commonly regarded as the result of the electron-induced reduction of Cu2 O. This paper describes a simple strategy using Cu2 O as a dark cathode and TiO2 as a photoanode to achieve stable aqueous CO2 reduction with a high Faradaic efficiency of 87.4 % and a selectivity of 92.6 % for carbonaceous products. We have shown that the photogenerated holes, instead of the electrons, primarily account for the instability of Cu2 O. Therefore, Cu2 O was used as a dark cathode to minimize the adverse effects of holes, by which an improved stability was achieved compared to the Cu2 O photocathode under illumination. Additionally, direct exposure of the Cu2 O surface to the electrolyte was identified as a critical factor for the high selectivity for carbonaceous products.
authors.affiliation: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Chang
authors.affiliation: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
authors.forename: Tuo
authors.initials: T
authors.lastname: Wang
authors.affiliation: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
authors.forename: Yijia
authors.initials: Y
authors.lastname: Wei
authors.affiliation: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
authors.forename: Jiubing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University; Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China. jlgong@tju.edu.cn.
authors.forename: Jinlong
authors.identifier: 0000-0001-7263-318X
authors.initials: J
authors.lastname: Gong
keywords: carbon dioxide reduction; cuprous oxide; photocatalysis; photoelectrochemistry; stability