TiO2/Zn0.5Cd0.5S heterojunction for efficient photocatalytic degradation of methylene blue and its photocatalytic mechanism

[Display omitted] •The decolorization rate of 90%-TiO2/Zn0.5Cd0.5S reaches 94.2% at 240 min, which is 2.1 times that of Zn0.5Cd0.5S and 11.9 times that of TiO2.•According to the scavenger test, only O2–· is the active material that plays a major role in the degradation of methylene blue by TiO2/Zn0.5Cd0.5S photocatalyst.•In this paper, TiO2/Zn0.5Cd0.5S composites were prepared by coprecipitation-hydrothermal method, which resulted in the reduction of the forbidden band width of the materials. TiO2/Zn0.5Cd0.5S composites were prepared by co-precipitation-hydrothermal method.The two substances come together to form a heterojunction structure. After recombination, the band gap decreases, the response range to visible light becomes larger, the recombination efficiency of electron-hole pair becomes lower, and the electron transfer rate becomes faster. In the photocatalytic process, 90%-TiO2/Zn0.5Cd0.5S photocatalyst has the best effect, the decolorization rate reaches 94.2% at 240 min, and the reaction rate constant is 0.0142 min−1, respectively 2.1 times for Zn0.5Cd0.5S and 5.2 times that of TiO2, and the active group is O2–· during the degradation process.