Morphology controlled synthesis and photocatalytic study of novel CuS-Bi2O2CO3 heterojunction system for chlorpyrifos degradation under visible light illumination

In this study, Bi2O2CO3 (BSC) nanoplates with high aspect ratio and hierarchical nanostructures were prepared by hydrothermal technique using urea/hexamethylenetetramine as hydrolysing agent and KCl as additive in different solvent systems. The relative molar proportion of urea and KCl was crucial for phase purity as well as thickness and planar dimension of the BSC plates. The BSC nanoplates were used as substrates to prepare CuS-Bi2O2CO3 (CuS/BSC) direct z-scheme heterojunction systems. The heterojunction materials were characterized by FESEM, HRTEM, XRD, PL, FTIR and UV-Vis-DRS techniques. The presence of crystalline tetragonal BSC and hexagonal covellite CuS phase was inferred from XRD study. Morphologically, the CuS/BSC material contained CuS nanorods and BSC nanoplates. HRTEM study suggested microscopic close contact between the CuS nanorods and BSC nanoplates. Optical property study revealed improvement in visible light absorption and enhanced separation of excitons. The CuS/BSC materials were used as photocatalyst for chlorpyrifos pesticide degradation under visible light irradiation. The heterojunction materials were highly active achieving > 95% degradation within 3 h of reaction. The pathway and mechanism of CP degradation was elucidated using GCMS and radical scavenger experiments.