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

Poor stability and light absorption are the main factors hindering the application of Cs 4 PbBr 6 nanocrystals (NCs) in photocatalysis, and acquiring heterostructure of semiconductor/perovskite still is a challenging task. Here, we successfully synthesized Cs 4 PbBr 6 NCs and then coated with titania (TiO 2 ) to construct Cs 4 PbBr 6 /CsPbBr 3 @TiO 2 ternary heterojunction by one-pot water-triggered conversion. The newly formed interface phase of CsPbBr 3 between Cs 4 PbBr 6 NCs and TiO 2 enhanced visible-light absorption capacity of composites, promoting the effective separation and transfer of photoelectron–hole pairs. CsPbBr 3 interfacial phase levels in Cs 4 PbBr 6 /CsPbBr 3 @TiO 2 can be regulated by controlling water content, and its content can affect the photocatalytic performance of the obtained composites. Ternary Cs 4 PbBr 6 /CsPbBr 3 @TiO 2 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 CsPbBr 3 @TiO 2 and commercial P25, respectively. Meanwhile, the obtained composite shows good stability in the water system. This work demonstrates a critical interface modulation action of CsPbBr 3 for the application of Cs 4 PbBr 6 NCs in the fields of photocatalysis. • Cs 4 PbBr 6 /CsPbBr 3 @TiO 2 heterostructure was fabricated by water-triggered conversion for photocatalytic application. • CsPbBr 3 interfacial phase enhanced visible-light absorption and boosted separation and transfer of photogenerated carriers. • Ternary composite had high photocatalytic degradation activity for TC under visible-light irradiation. • Our work proved a critical interface modulation of CsPbBr 3 for the application of Cs 4 PbBr 6 phase in photocatalysis.