An S-Scheme CeO2/Bi2O2S heterojunction photoanode for the photoelectrocatalytic degradation of sulfamethoxazole in synthetic and real wastewater
Kehinde D. Jayeola, Dimpo S. Sipuka, Tsholofelo I. Sebokolodi, Oluchi V. Nkwachukwu, Charles Muzenda, Babatunde A. Koiki, Jonathan O. Babalola, Minghua Zhou, Omotayo A. Arotiba
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.