Preparation of HC/BiOCl composite photocatalyst and its visible photocatalytic performance

The wide band gap of BiOCl limits its application in the visible region. In this study, biochar (HC) and BiOCl were combined to synthesize HC/BiOCl composites with good visible light catalytic activity by a simple and efficient solvothermal method. The morphology and composition of the samples were characterised by SEM, TEM, XRD, XPS and UV–Vis spectra. The degradation ability of Rhodamine B (RhB) by HC/BiOCl with different biochar doping levels was investigated under 70 W metal halide lamp irradiation. The results show that HC/BiOCl has strong photocatalytic degradation ability and good cyclic stability for RhB. After 70 W metal halide lamp irradiation for 40 min, the degradation efficiency of RhB reached 98.07 %, and its kinetic rate constant is about 3.04 times that of BiOCl monomer. It is found that HC/BiOCl has low electron hole recombination, high photogenerated carrier separation rate and strong visible light absorption capacity, which are the main reasons for its good photocatalytic activity. The mechanism studies found that holes (h+) and superoxide radicals (O2−) are the main active species during the photocatalytic reaction process. In this paper, peanut shells were used as the raw material of biochar, which is conducive to the recycling of agricultural waste and the reduction of secondary environmental pollution. At the same time, the prepared HC/BiOCl can efficiently degrade organic pollutants at low energy consumption (70 W metal halide lamp). Therefore, this paper provides a feasible and environmentally friendly solution for the degradation of organic pollutants.