Inorganic Ultrathin 2D Photocatalysts: Modulation Strategies and Environmental/Energy Applications

Abstract

ConspectusPhotocatalysis technology has gained extensive attention in the past few decades due to its potential to alleviate or solve energy and environmental contamination problems. The development and design of new photocatalytic semiconductor materials with high catalytic activity has become a research hotspot in this field. In recent years, inorganic ultrathin two-dimensional (2D) semiconductor photocatalysts have shown excellent performance in photocatalytic applications due to their high specific surface area, clear atomic structure, unique electronic structure, intrinsic quantum confined electrons, and high atomic exposure ratio. When the thickness of the bulk semiconductor is decreased to the atomic level, its local atomic structure changes prominently. This is a major reason why the atomic thin 2D materials could show improved inherent properties and produce new properties that are not available in the corresponding bulk semiconductors. Furthermore, compared with the bulk photocatalysts, the surface electronic structure of inorganic ultrathin 2D materials is more sensitive and thus could be regulated more easily by surface and interfacial modification methods, leading to great optimization of photocatalytic properties. Therefore, inorganic ultrathin 2D materials not only provide an ideal reaction model for clearly revealing the relationships between surface/interface structure characteristics and photocatalytic performance but also bring new opportunities for the development of efficient catalysts to resolve energy crises and environmental problems.In this Account, we summarize our previous work on the applications of inorganic ultrathin 2D nanomaterials in the field of photocatalysis. First, we briefly introduce the classification and controlled fabrication of inorganic ultrathin 2D nanomaterials, including metal chalcogenides, bismuth-based photocatalysts, metal oxides, and metal-free materials. Then, we focus on the surface and interfacial modification strategies for effectively engineering the photocatalytic activity of 2D photocatalysts, including defect engineering, metal doping, single atom loading, and heterojunction construction. These strategies can effectively adjust the inherent physical and chemical properties of inorganic ultrathin 2D nanomaterials, change their electronic structure to improve the light absorption ability, promote the separation and migration of photogenerated electrons and holes, optimize the catalytic active sites, and even change the reaction energy barrier of the photocatalytic reaction. Additionally, we discuss the research progress of inorganic ultrathin 2D photocatalysts in hydrogen evolution, contaminant removal, and sterilization. Finally, we put forward the prospects, challenges, and novel viewpoints of feasible solutions of inorganic ultrathin 2D materials in photocatalysis applications. Overall, this Account provides in-depth insight into modulation strategies and the structure–activity relationship of inorganic ultrathin 2D materials for researchers in photocatalytic fields, which is beneficial to accelerate the practical applications of inorganic ultrathin 2D materials in the field of environment and energy.