Efficient photocatalysis enabled by lignocellulose-derived carbon-modified BiOBr: Unlocking the key component in lignocellulose

The adoption of green lignocellulose-derived carbon to modify semiconductors for efficient photocatalysis is highly important, and the key component of lignocellulose urgently needs to be defined since lignocellulose is composed of lignin, cellulose, and hemicellulose. In this study, poplar wood-derived carbon-modified BiOBr (BiOBr/PWC) was facilely constructed via a hydrothermal method for photocatalytic Cr(VI) reduction under visible light. BiOBr/PWC has a distinctive flower-like morphology with a relatively high surface area, and enables efficient charge carrier separation. The Cr(VI) reduction rate over BiOBr/PWC dramatically improves to 95 % in comparison with those over BiOBr (6 %) and PWC (14 %). Poplar lignin-, cellulose-, and hemicellulose-derived carbon were separately integrated with BiOBr for photocatalytic Cr(VI) reduction, and the reduction rates are 87 %, 62 %, and 62 %, respectively. Poplar lignin-derived carbon possesses the maximum degree of graphitization, and the corresponding BiOBr/carbon has an open pore structure, which is more conducive to charge carrier transmission and light absorption. Thus, lignin in poplar wood plays a dominant role in achieving the efficient photocatalysis of BiOBr/PWC. This work is the first to reveal the role of components in lignocellulose-derived carbon for photocatalysis, which will greatly advance the development of biochar-based photocatalysts.