Core-shell structured Z-scheme AgS/AgIO composites for photocatalytic organic pollutants degradation.

Constructing direct Z-scheme system is a promising strategy to boost the photocatalytic performance for pollution waters restoration, but it is of great challenge because of the requirement of appropriately staggered energy band alignment and intimate interfacial interaction between semiconductors. Herein, a class of core-shell structured AgS-AgIO Z-scheme heterostructure photocatalysts are designed and developed. AgS is generated by the in-situ ion exchange reaction and anchored on the surface of AgIO, so the intimate interface between AgIO and AgS is realized. Integration of AgIO and AgS extends the ultraviolet absorption of AgIO to Vis-NIR region, and also promote the charge separation and migration efficiency, contributing to the enhanced photocatalysis activity for composite catalysts. The optimal AgS-AgIO-4 catalyst exhibits a MO photo-degradation rate constant of 0.298 h, which reaches 5.77 and 11.4-folds higher than that of AgIO (0.044 h) and AgS (0.024 h). The as-obtained composite catalyst exhibits universally photocatalytic activity in disintegrating diverse industrial pollutants and pharmaceuticals. Particularly, driven by natural sunlight, the AgS-AgIO-4 can effectively decompose MO. A plausible Z-scheme photocatalytic mechanism and reaction pathways of MO degradation over composite catalyst are systemically investigated and proposed.