A oxygen vacancy-modulated homojunction structural CuBi2O4 photocathodes for efficient solar water reduction

Shenqi Wei; Chenglong Wang; Xuefeng Long; Tong Wang; Peng Wang; Mingrui Zhang; Shuwen Li; Jiantai Ma; Jun Jin; Lan Wu

doi:10.1039/D0NR04473C

A oxygen vacancy-modulated homojunction structural CuBi₂O₄ photocathodes for efficient solar water reduction†

Shenqi Wei,^a Chenglong Wang,^a Xuefeng Long,^a Tong Wang,^a Peng Wang,^a Mingrui Zhang,^b Shuwen Li,

^a Jiantai Ma,

^a Jun Jin

*^a and Lan Wu*^b

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* Corresponding authors

^a State Key Laboratory of Applied Organic Chemistry (SKLAOC), The Key Laboratory of Catalytic Engineering of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu, P. R. China
E-mail: jinjun@lzu.edu.cn

^b College of Chemical Engineering, Northwest University for Nationalities, Lanzhou, Gansu 730030, P.R. China
E-mail: wulan@xbmu.edu.cn

Abstract

The photoelectrochemical (PEC) water reduction performance of CuBi₂O₄ (CBO)-based photocathodes is still far from their theoretical values due to low bulk and surface charge separation efficiencies. Herein, we propose a regrowth strategy to prepare a photocathode with CBO coating on Zn-doped CBO (CBO/Zn-CBO). Furthermore, NaBH₄ treatment of CBO/Zn-CBO introduced oxygen vacancies (O_v) on CBO/Zn-CBO. It was found that Zn-doping not only increases the charge carrier concentration of CBO, but also leads to appropriate band alignment to form homojunctions. This homojunction can effectively promote the separation of electron–hole pairs, thus obtaining excellent photocurrent density (0.5 mA cm⁻² at 0.3 V vs. RHE) and charge separation efficiency (1.5 times than CBO). The following surface treatment induced O_v on CBO/Zn-CBO, which significantly increased the active area of the surface catalytic reaction and further enhanced the photocurrent density (0.6 mA cm⁻²). In the absence of cocatalysts, the electron injection efficiency of O_v/CBO/Zn-CBO was 1.47 times improved than that of CBO. This work demonstrates a homojunction photocathode with O_v modulation, which provides a new view for future photoelectrochemical water splitting.

Nanoscale

A oxygen vacancy-modulated homojunction structural CuBi₂O₄ photocathodes for efficient solar water reduction†

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A oxygen vacancy-modulated homojunction structural CuBi₂O₄ photocathodes for efficient solar water reduction

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