Recent advances in kaolinite-based material for photocatalysts

ABSTRACT The composite catalytic materials based on the mineral kaolinite are considered to be a potential approach for solving global energy scarcity and environmental pollution, which have excellent catalytic performance, low cost and excellent chemical stability. However, pure kaolinite does not have visible light absorption ability and cannot be used as a potential photocatalytic material. Fortunately, the unique physical and chemical properties of kaolinite can be acted as a good semiconductor carrier. Herein, this paper firstly presents the mineralogical characteristics of kaolinite. Next, kaolinite-based photocatalysts (such as TiO2/kaolinite, g-C3N4/kaolinite, g-C3N4/TiO2/kaolinite, ZnO, and etc.) were discussed in detail from the formation of heterostructures, synthesis-modification methods, photocatalytic mechanisms, and electron transfer pathways. Furthermore, the specific role of kaolinite in photocatalytic materials is summarized and discussed. In addition, the photocatalytic applications of kaolinite-based photocatalysts in the fields of water decomposition, pollutant degradation, bacterial disinfection are reviewed. However, the modification of kaolinite is hard, the manufacture of a large number of kaolinite-based photocatalysts is difficult, the cost of doping noble metals is expensive, and the utilization rate of visible light is low, which limits its application in industrial practice. Finally, this paper presents some perspectives on the future development of kaolinite-based photocatalysts.