Preparation of meso-tetraphenyl porphyrin modified defect-rich BiOCl with enhanced visible-light photocatalytic activity for antibiotic degradation and mechanism insight

Abstract

The exploration of effective photocatalysts used in wastewater treatment containing antibiotics is of significant importance for addressing the universal environment problems. In this work, the meso-tetraphenyl porphyrin (TPP) with conjugated macrocyclic π-electrons structure was successfully combined with defect-rich BiOCl to form ultrathin sheet-like TPP/defect-rich BiOCl composite as visible-light-responsive photocatalyst. The morphologies, crystal structures, chemical constitutions, optical and photo-electrochemical properties of the as-obtained photocatalyst were determined. The TPP/defect-rich BiOCl composite showed enhanced photocatalytic ability for the degradation of colorless antibiotic TC, CIP and ENR under visible light irradiation compared to defect-rich BiOCl. The effect of different TPP contents on the photodegradation activity was also investigated, and 2 wt% TPP/defect-rich BiOCl exhibited the optimal photocatalytic ability. According to the radicals trapping experiments and electron spin resonance (ESR), the hole (h+), superoxide radical (O2•−) and hydroxyl radical (•OH) contributed to the process of organic pollutant photo-degradation. The good recyclability of the photocatalyst was verified through cyclic measurements. Furthermore, a possible photodegradation mechanism was raised to clarify the effective separation and migration process of photo-induced charge carriers.