Enhanced visible-light photocatalytic decomposition of 2,4-dichlorophenoxyacetic acid over ZnIn2S4/g-C3N4 photocatalyst

•A novel flower-on-sheet ZnIn2S4/g-C3N4 nanocomposite was synthesized.•ZnIn2S4/g-C3N4 showed high visible light catalytic activity for 2,4-D degradation.•The photocatalytic degradation pathway of 2,4-D was investigated. ZnIn2S4/g-C3N4 heterojunction photocatalyst was successfully synthesized via a simple hydrothermal method and applied to visible-light photocatalytic decomposition of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous phase. The flower-like ZnIn2S4 particles were dispersed on the surface of g-C3N4 nanosheets in the ZnIn2S4/g-C3N4 composite. The composite showed higher separation rate of electron-hole pairs as compared to ZnIn2S4 and g-C3N4. Consequently, the ZnIn2S4/g-C3N4 composite exhibited enhanced visible light photocatalytic decomposition efficiency of 2,4-D, within 20% ZnIn2S4/g-C3N4 composite owning the highest photocatalytic efficiency and initial rate. The initial rates of 2,4-D degradation on g-C3N4, ZnIn2S4, and 20% ZnIn2S4/g-C3N4 were 1.23, 0.57 and 3.69mmol/(gcath), respectively. The h+ and O2− were found to be the dominant active species for 2,4-D decomposition. The photocatalytic degradation pathways of 2,4-D by ZnIn2S4/g-C3N4 under visible light irradiation were explored. The ZnIn2S4/g-C3N4 composite displayed high photostability in recycling tests, reflecting its promising potential as an effective visible light photocatalyst for 2,4-D treatment.