Construction of Z-scheme Ti/Ga co-doped ZnO heterostructure photocatalyst with graphitic carbon nitride for efficient visible-light-driven dye degradation

Innovative solar-driven heterostructure photocatalysts are promising for removing the organic contaminants in the water environment. In this work, a sequence of well-defined Z-scheme Ti-Ga co-doped ZnO/g-C3N4 (TGZ/CN) heterostructure photocatalysts were developed via a simple sol-gel method and the single-phase dispersion method in order to realize the cooperative improvement from the Ti/Ga co-doping and construction of heterostructure. The synthesized samples were analyzed by a variety of characterization techniques, and the photocatalytic activity was assessed by photodegradation of methylene blue (MB) under visible light irradiation. Compared to the ZnO and g-C3N4, the TGZ/CN composite demonstrated higher photocatalytic performance for the degradation of MB indicating an efficient photocatalytic degradation rate of 95.4% in 105 min under visible light. Moreover, the TGZ/CN photocatalyst exhibited excellent stability after five cycles of MB photodegradation. Furthermore, the as-prepared composites' possible photocatalytic mechanism was discussed in detail. The improved photocatalytic performance primarily resulted from the effectively reduced band gap of ZnO after Ti/Ga co-doping and the facilitated separation of photoexcited e(-)/h(+) pairs caused by the construction of Z-scheme heterojunction. This work offers novel insights in developing hybrids with highly efficient photocatalytic activity towards future environmental applications.