Hydroxyl radicals always play important role in the photocatalytic degradation of pollutants and thus lots of efforts have been made to enlarge their amount. Herein, BiOCl photocatalysts with different surface hydroxyl groups amount are synthesized using ionic liquid self-combustion (C-BiOCl) and hydrothermal method (H-BiOCl) to deep understand the roles of hydroxyl radicals in toluene mineralization. It is found that hydroxyl radicals in H-BiOCl have reverse inhibitory effect on the ring-opening reaction in the photocatalytic mineralization process of toluene and C-BiOCl exhibits more excellent ability and stability in mineralizing toluene. The reason is that C-BiOCl lacking hydroxyl groups can selectively generate benzoic acid by holes and superoxide anion radicals; while H-BiOCl with large number of hydroxyl groups will lead to the production of hydroxyl radicals and phenolic intermediates, which will preferentially cover active sites such as oxygen vacancies, thereby reducing the performance and stability of the catalyst.

羟基自由基在污染物的光催化降解中一直发挥着重要作用，因此人们做出了很多努力来扩大其数量。本文采用离子液体自燃法（C-BiOCl）和水热法（H-BiOCl）合成了不同表面羟基量​​的BiOCl光催化剂，以深入了解羟基自由基在甲苯矿化中的作用。发现H-BiOCl中的羟基自由基对甲苯光催化矿化过程中的开环反应具有反向抑制作用，C-BiOCl对甲苯的矿化能力和稳定性更加优异。原因是缺乏羟基的C-BiOCl可以通过空穴和超氧阴离子自由基选择性地生成苯甲酸；