Surface Oxygen-Defective ZIF-8/Bi7O9I3 Nanocomposite for Effective Photocatalytic Degradation of Sulfonamide

Abstract

Photocatalysts offer a promising solution to water pollution, with ongoing research focused on identifying suitable materials for removing dyes, pharmaceuticals, and heavy metals. Therefore, this study aims to synthesize a surface oxygen-defective ZIF-8/Bi₇O₉I₃ nanocomposite for sulfonamide degradation under visible light irradiation. Electron spin resonance and X-ray photoelectron spectroscopy analysis revealed the presence of oxygen defects in ZIF-8@Bi₇O₉I₃ photocatalysts. The optimum ZIF-8@Bi₇O₉I₃ nanocomposite achieved 96.12% degradation of sulfonamide after 180 min. The enhanced photocatalytic degradation performance was attributed to the presence of oxygen vacancies, which trap electrons and reduce recombination rates in the nanocomposites. Furthermore, the effects of the initial pollutant pH and catalyst dose on photodegradation performance were investigated and optimized. Recycling tests showed no decrease in degradation rate after five consecutive cycles. Electrochemical analysis revealed efficient charge transfer resistance and reduced recombination rate in the nanocomposite. Scavenger assays were employed to identify the main reactive species involved in photocatalytic degradation. The degradation system in this study was primarily driven by superoxide (.O₂⁻) and hydroxy radicals (.OH). These findings form the basis for a proposed photocatalytic degradation mechanism.