Visible light-induced photocatalytic degradation of tetrabromobisphenol A on platinized tungsten oxide

In this study, we investigated the degradation of the flame retardant tetrabromobisphenol A (TBBPA) using platinized tungsten oxide (Pt/WO₃), synthesized via a simple photodeposition method, under visible light. The results of degradation experiments show a significant enhancement in TBBPA degradation upon surface platinization of WO₃, with the degradation rate increasing by 13.4 times compared to bare WO₃. The presence of Pt on the WO₃ surface stores conduction band electrons, which facilitates the two-electron reduction of oxygen and enhances the production of valence band holes (h_VB⁺) and hydroxyl radicals (^●OH). Both h_VB⁺ and ^●OH are significantly involved in the degradation of TBBPA in the visible light-irradiated Pt/WO₃ system. This was verified through fluorescence spectroscopy employing coumarin as a chemical probe and oxidizing species-quenching experiments. The analysis of degradation products and their toxicity assessment demonstrate that the toxicity of TBBPA-contaminated water is significantly reduced after Pt/WO₃ photocatalysis. The degradation rate of TBBPA increased with increasing Pt/WO₃ dosage, reached an optimum at a Pt content of 0.5 wt%, but decreased with increasing TBBPA concentration. The decrease in degradation efficiency of Pt/WO₃ was minor, both in the presence of various anions and after repeated use. This study proposes that Pt/WO₃ is a viable photocatalyst for the degradation of TBBPA in water under visible light.