BiOCl1−xBrx solid solution – Novel synthesis, highly-efficient visible-light-driven photocatalyst, and DFT study

Among various advanced oxidation processes applied in wastewater treatment, photocatalysis has attracted attention in research and industry due to its advantages, such as low cost, high efficiency, and eco-friendliness. With a unique layered structure, bismuth oxyhalides have been widely applied as high-efficiency photocatalysts for organic pollutant degradation in the aqueous environment. However, the large bandgap of BiOCl and the high recombination rate of BiOBr limit their practical application. Tuning bandgap by forming a solid solution is an efficient method to engineer bandgap and prolong the lifetime of photo-induced electron-hole pairs. In this study, a facile solid-state reaction in a vapor chamber was applied to prepared solid solutions of BiOCl _1−xBr _x . Their photocatalytic performance is significantly improved in comparison with the end components. The optimal composition at x = 0.5 performed degradation efficiencies of 92.3% and 82.6% for rhodamine B and tetracycline degradation, after 70 mins of reaction under light emitting diode (LED) irradiation, respectively. This improvement is attributed to the reduction in bandgap and the effective charge recombination due to the favorable electronic and crystal structure variation, demonstrated by the photoelectrochemical results and density functional theory calculation.