Photocatalytic degradation of bisphenol A over Co-BiOCl/biochar hybrid catalysts: Properties, efficiency and mechanism

Abstract

In our research, Co-BiOCl/biochar hybrid catalysts were successfully combined using a facile hydrothermal process and applied in the degradation of bisphenol A (BPA) under vacuum ultraviolet/ultraviolet (VUV/UV) irradiation. The results showed that the biochar loading and cobalt (Co) doping strategies enhanced the catalytic efficiency of BiOCl for the removal of BPA (93.8%) via a narrower band gap, a stronger ultraviolet response, and higher electron/hole (e−/h+) pairs separation. According to the first-principles calculations, the energy band gap of Co-BiOCl was 1.47 eV, which was 1.19 eV lower than that of BiOCl (2.66 eV). Under the optimum operating conditions, a BPA elimination rate of over 90% was achieved in 90 min even after five cyclic experiments were performed. This implied the synthetic Co-BiOCl/biochar catalyst presented optimized photocatalytic activity and stability. Furthermore, trapping experiments demonstrated that hydroxyl radicals (OH), photogenerated holes (h+), superoxide radicals (O2−), and hydrated electrons (eaq−) were the main participating species in BPA degradation by the Co-BiOCl/biochar catalyst under VUV/UV illumination. Significantly, LC-MS was used to propose a probable BPA degradation pathway. Moreover, the photocatalytic mechanism of the Co-BiOCl/biochar catalysts for BPA degradation under VUV/UV illumination was also investigated by the first-principles calculations.