Mechanistic insights into the reaction pathway for efficient cationic dye photocatalytic degradation and the importance of the enhanced charge isolation over dual Z-scheme CeO2/BiOCl/Ag2WO4 photocatalyst

Fabricating a multi-component heterojunction system with enhanced charge isolation efficacy remains challenging. A photoactive CeO2/BiOCl/Ag2WO4 heterojunction was successfully constructed using a coprecipitation technique to degrade crystal violet and methylene blue dyes. It was found through a combination of characterization and experiments that the dual Z-scheme system not only augmented the charge isolation and migration efficiency but also maintained superior redox ability with extended visible light absorption capacity. In the CeO2/BiOCl/Ag2WO4 system, 97 % of methylene blue and 98 % of crystal violet were degraded in 75 min using 50 mg/L of ternary photocatalyst. The rate of reaction of CeO2/BiOCl/Ag2WO4 for methylene blue (0.0445 min(-1)) and crystal violet (0.05053 min(-1)) exhibited a multi-fold increase in comparison to the bare photocatalysts. The electron spin resonance (ESR) analysis has remarkably identified hydroxyl and superoxide radicals (center dot OH, center dot O-2(-)) as the primary reactive species in the photodegradation process. Liquid chromatographymass spectrometry analysis was utilized to obtain potential degradation pathways for methylene blue and crystal violet, respectively. The dual charge transferal mechanism by the ternary photocatalyst resulted in a significant increase in photocatalytic activity. It provided new perspectives on the principles guiding the rational development of a multicomponent system for environmental remediation.