Band Engineering of BiFeO<sub>3</sub> Nanosheet for Boosting Hydrogen Evolution by Synergetic Piezo-photocatalysis
Yanhu Wang, Mengchun Yang, Kang Cui, Lina Zhang, Xiao Wang, Shenguang Ge, Jinghua Yu, Zhenxiang Cheng
Abstract
Hydrogen (H 2 ) production through water splitting using sustainable energy sources is gaining increasing attention. However, limited catalytic performance based on a single driving force presents both opportunities and challenges for achieving a high-efficiency H 2 output. Exploring multiple driving sources to enhance the comprehensive catalytic performance shows great promise. BiFeO 3 (BFO), with features of narrow band gap and ultrahigh ferroelectric polarizations, is considered as a promising alternative candidate for green H 2 production from water splitting. However, the inherent overpositive conduction band edge restricts its applications. Therefore, a strategy involving band engineering through heteroatom Co-doping (Co x -BFO) has been proposed to boost piezo-photocatalytic H 2 evolution performance. Based on the synergetic effects of the polarization field induced by piezoelectric Co 1.8 -BFO, suppressed recombination of charge carriers, prolonged charge carrier lifetime, modulated band alignment, and lowered energy barrier for surface H 2 O adsorption/activation/reduction, the Co 1.8 -BFO nanosheets exhibit significant piezo-photocatalytic activities with an enhanced H 2 generation rate (321.9 μmol·g –1 ·h –1 ). That rate is much higher than those of piezocatalytic (127 μmol·g –1 ·h –1 ) and photocatalytic (163 μmol·g –1 ·h –1 ) performances alone. This work provides an effective approach to advancing the BFO water splitting performance through band engineering.