Activity and stability of TiO2-encapsulated CsPbBr3/Cs4PbBr6 for photocatalytic degradation of Rhodamine B

Abstract

Due to the excellent optoelectronic performance of cesium lead bromide(CsPbBr3), it has shown promising potential as a photocatalyst for the degradation of organic compounds under sunlight. During the synthesis of CsPbBr3, Cs4PbBr6, another formation of CsPbBr3, is also produced, which exhibits desirable properties such as strong and narrow photoluminescence (PL) and enhanced thermal stability. In this study, we successfully synthesized a mixture of CsPbBr3/Cs4PbBr6 nanoparticles using a simple precipitation method. However, the stability of CsPbBr3/Cs4PbBr6 was found to be sensitive to high temperatures, moisture, and oxygen, which could affect its photocatalytic degradation performance. To enhance both stability and activity, we employed the technique called the one-step water-triggered transformation method by encapsulating CsPbBr3/Cs4PbBr6 nanoparticles with a protective layer of titanium dioxide (TiO2), creating a perovskite/metal-oxide composite. This composite plays a crucial role in facilitating efficient charge transfer and separation, which are essential for successful photocatalytic processes. To achieve optimal results, we varied the reaction temperatures (95, 110, 125, and 140°C), drying conditions (80°C for 2 h, 80°C overnight, and at room temperature overnight), and mass ratio between CsPbBr3/ Cs4PbBr6 to tetrabutyl titanate (1:1, 1:2, 1:3, and 1:4). The results demonstrated that the stability of TiO2-encapsulated CsPbBr3/ Cs4PbBr6 could be significantly enhanced by undergoing a reaction temperature of 95 °C and drying condition at 80 °C for 2 h. Moreover, when the mass ratio between CsPbBr3/Cs4PbBr6 was set at 1:3, the material exhibited a maximum surface area of 222 m2/g, resulting in the highest absorption and degradation activity. The kinetic rate constant was determined at 0.1053 min-1, enabling complete photocatalytic degradation within 30 min.