One-pot hydrothermal synthesis of g-C3N4/Ag/AgCl/BiVO4 micro-flower composite for the visible light degradation of ibuprofen

Abstract

A novel visible-light-driven g-C3N4/Ag/AgCl/BiVO4 micro-flower composite was synthesized by a simple one-pot hydrothermal method. Morphological and structural studies of the composite showed the formation of microsheets of different sizes (280–450 nm) and (1 2 1)/(0 4 0) as the preferential planes. Optical absorption examination of g-C3N4/Ag/AgCl/BiVO4 revealed its small band gap (Eg = 2.4 eV), which enables it to absorb light in the visible light region. The photocatalytic activity of the g-C3N4/Ag/AgCl/BiVO4 was determined by the photocatalytic degradation of ibuprofen (IBU) under visible light irradiation. Compared to BiVO4, Ag/AgCl/BiVO4 and g-C3N4/BiVO4, the g-C3N4/Ag/AgCl/BiVO4 showed remarkable efficiency by degrading 94.7% of IBU in 1 h at a photocatalyst dosage of 0.25 g/L. Furthermore, the photocatalytic degradation performance of g-C3N4/Ag/AgCl/BiVO4 increased when the intensity of the (1 2 1)/(0 4 0) planes increased. Under dark conditions, insignificant adsorption of IBU was observed on the surface of g-C3N4/Ag/AgCl/BiVO4 due to its low surface area (3.67 m2g−1). The excellent photocatalytic activity is likely due to visible light absorption and increased lifetime of photogenerated electron-hole pairs along the heterojunction. The kinetics of the IBU photodegradation was found to follow the pseudo-first-order reaction. The influence of the key parameters during synthesis (i.e., pH, amount of g-C3N4, amount of AgNO3, photodeposition time, and autoclaving time) on the photocatalytic activity of g-C3N4/Ag/AgCl/BiVO4 was also investigated. It was found that the Ag content and pH are the most crucial parameters in the enhancement of photocatalytic activity. The g-C3N4/Ag/AgCl/BiVO4 produced 4.8 µmol of CO2 showing its mineralization and the remaining intermediates were confirmed by LCMS.