Dual heterojunctions and sulfur vacancies of AgInS2/rGO/MoS2 co-induced photocatalytic degradation of tetracycline hydrochloride

Abstract

The construction of dual heterojunctions in semiconductors can boost light harvesting, spatial separation of photogenerated electron-hole pairs, as well as photocatalytic efficiency. Sulfur vacancies, as prevalent point defects in semiconductors, can act as active sites for trapping electrons to maneuver charge transfer and separation and surface catalytic reactions. Moreover, the mechanism of synergy of dual heterojunctions and sulfur vacancies co-induced the formation of interfacial electric field should be revealed. In this paper, sulfur vacancies doped AgInS2/rGO/MoS2 dual heterojunctions were prepared via two-step hydrothermal method. Excellent photoelectrochemical performance was achieved on the AgInS2/rGO/MoS2 because sulfur vacancies served as “high-speed electrons trappers”, which may effectively inhibit the recombination of photogenerated charge carriers. Furthermore, the optimal AgInS2/rGO/MoS2, with the molar ratio of AgInS2 and MoS2 equaling 1:1, exhibited high photocatalytic efficiency in removing tetracycline hydrochloride under visible light irradiation. The remarkable photocatalytic activity of AgInS2/rGO/MoS2 can be attributed to the formation of multiple charge transfer pathways between the interfacial layers of Z-scheme heterojunction and rGO-n junction, deriving from the synergistic effect of dual heterojunction and sulfur vacancies. This work offers a promising way into designing dual-heterojunction and intrinsic defect co-induced photocatalysts for removing harmful antibiotic pollutants.