Tendencies of alloyed engineering in BiOX‐based photocatalysts: a state‐of‐the‐art review

Abstract Energy‐saving and environmentally friendly photocatalysis has emerged as a popular research area in response to issues with energy scarcity and environmental degradation. Due to the unique layer‐like structure, BiOX (Cl, Br, I) is frequently used in photocatalysis. However, inherent flaws in BiOX, such as an inappropriate band gap and low carrier separation efficiency, restrict its capacity for photocatalysis. Owing to the tunable grouping layer, alloying engineering is employed to optimize the intrinsic properties of BiOX and alloyed BiOX becomes a promising photocatalytic material. This review describes the structure of BiOX, where tunable halogen layers provide favorable conditions for the implementation of alloying engineering to improve intrinsic properties. The article compares the effects and mechanisms of alloying engineering on the optimization of the energy band structure and carrier behavior of BiOX, and lists various modification methods used to improve the optimization of the intrinsic properties by alloying engineering, including defect engineering, morphology control as well as the synergy between alloying and other modification methods (bismuth‐rich strategies, cation doping, construction of heterojunctions and plasma resonance effects). Subsequently, applications of alloyed BiOX in energy and environmental fields are summarized, including contaminant degradation, antibacterial, CO 2 reduction, nitrogen fixation and organic synthesis. Finally, we summarize the current challenges and future directions of alloyed BiOX. It is expected that this work will provide guidance and assistance for an in‐depth study and understanding of the mechanisms of alloying engineering to optimize intrinsic properties and design alloyed BiOX with higher photocatalytic activity.