An S-Scheme CeO2/Bi2O2S heterojunction photoanode for the photoelectrocatalytic degradation of sulfamethoxazole in synthetic and real wastewater

Abstract

• Photoelectrocatalytic degradation of sulfamethoxazole in synthetic/real wastewater. • Band gap engineering of CeO 2 /Bi 2 O 2 S heterojunction as photoanode. • CeO 2 /Bi 2 O 2 S achieves remarkable photoelectrocatalytic degradation efficiency. • The degradation efficiency was due to S-scheme configuration of CeO 2 /Bi 2 O 2 S. • Mechanism of charge transfer and PEC degradation pathways are proposed. We prepared an S- scheme heterojunction photoanode using cerium oxide (CeO 2 ) and bismuth oxysulfide (Bi 2 O 2 S) for the photoelectrocatalytic degradation of sulfamethoxazole. The CeO 2 /Bi 2 O 2 S photoanode was synthesised via an in-situ hydrothermal method, ensuring strong contact and efficient charge transfer between the CeO 2 and Bi 2 O 2 S. The materials and photoanode were characterized with XRD, XPS, photoluminescence, and photoelectrochemistry. The S-scheme configuration observed in the formation of heterojunction in CeO 2 /Bi 2 O 2 S photoanode was responsible for the improved photoelectrocatalytic performance for the visible light-assisted degradation of sulfamethoxazole. Operational parameters such as the effect of pH and current density were examined. The extent of sulfamethoxazole mineralisation was calculated to be 72 % using the total organic carbon (TOC) measurement. The LC-MS analysis was used to predict the degradation pathway and products. Furthermore, the photoelectrocatalytic efficiency of the CeO 2 /Bi 2 O 2 S photoanode was investigated in real wastewater matrices with TOC removal of 54 %. Therefore, the S scheme CeO 2 /Bi 2 O 2 S photoanodes lends itself to photoelectrochemical water treatment applications.