Facile construction of silver-based solid solution heterophase for efficient visible-light-driven photocatalytic degradation of tetracycline

Silver-based solid solutions as photocatalysts exhibit potential applications owing to the unique crystal and electronic structures, but single phase usually encounters low separation efficiency of photoinduced carriers and poor visible-light absorption, causing low photocatalytic activity. Thus, it is meaningful to design novel solid solution photocatalysts to solve these issues. In this work, mixed-phase heterostructures of ?/?-AgAl0.4Ga0.6O2 solid solution are in-situ obtained by phase transformation of ?-AgAl0.4Ga0.6O2 pre-prepared by a simple solidstate reaction. The study of phase and microstructure demonstrates that the mixed-phase heterostructure includes two phases of ? and ?-AgAl0.4Ga0.6O2 with high crystallinity. Platelet-like ? phase is combined with polyhedral ? phase, yielding close contract and large interfaces owing to in-situ preparation by phase transformation. The UV?vis absorption edge of mixed-phase heterostructure can be controlled from 500 to 575 nm through the energy band overlap of two phases. The mixed-phase heterostructure exhibits the improved visiblelight photocatalytic performance. The degradation rate of tetracycline reaches 87% in comparison to the 31% for ? phase and the 69% for ? phase. This is mainly attributed to the enhanced carrier separation and migration efficiency verified by photoelectrochemical investigation. Especially, the photocurrent value of mixed-phase heterostructure is 5 and 7 times higher than those of ? phase and ? phase, respectively. Considering the practical applications, the effects of tetracycline concentration, photocatalyst dosage, pH, and coexistence anions on the photocatalysis performance were investigated for tetracycline degradation. In addition, the recyclability, oxidization species, possible photocatalytic mechanisms were also studied and proposed. This work might promote the prospective research of semiconductor photocatalysis in wastewater purification.

Automated summary

This study developed a high-crystallinity mixed-phase heterostructure of silver-based solid solution through phase transformation, which significantly improved visible-light photocatalytic performance, especially in the degradation of tetracycline. Enhanced carrier separation and migration efficiency were observed, showing potential for promoting future research in semiconductor photocatalysis for wastewater purification.