Water-triggered conversion of Cs4PbBr6@TiO2 into Cs4PbBr6/CsPbBr3@TiO2 three-phase heterojunction for enhanced visible-light-driven photocatalytic degradation of organic pollutants

Abstract

Poor stability and light absorption are the main factors hindering the application of Cs4PbBr6 nanocrystals (NCs) in photocatalysis, and acquiring heterostructure of semiconductor/perovskite still is a challenging task. Here, we successfully synthesized Cs4PbBr6 NCs and then coated with titania (TiO2) to construct Cs4PbBr6/CsPbBr3@TiO2 ternary heterojunction by one-pot water-triggered conversion. The newly formed interface phase of CsPbBr3 between Cs4PbBr6 NCs and TiO2 enhanced visible-light absorption capacity of composites, promoting the effective separation and transfer of photoelectron–hole pairs. CsPbBr3 interfacial phase levels in Cs4PbBr6/CsPbBr3@TiO2 can be regulated by controlling water content, and its content can affect the photocatalytic performance of the obtained composites. Ternary Cs4PbBr6/CsPbBr3@TiO2 composite exhibits highest photocatalytic activity for degradation of Rhodamine B and tetracycline in water system under visible-light irradiation, which is higher than that of CsPbBr3@TiO2 and commercial P25, respectively. Meanwhile, the obtained composite shows good stability in the water system. This work demonstrates a critical interface modulation action of CsPbBr3 for the application of Cs4PbBr6 NCs in the fields of photocatalysis.