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

ZnIn 2 S 4 /g-C 3 N 4 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 ZnIn 2 S 4 particles were dispersed on the surface of g-C 3 N 4 nanosheets in the ZnIn 2 S 4 /g-C 3 N 4 composite. The composite showed higher separation rate of electron-hole pairs as compared to ZnIn 2 S 4 and g-C 3 N 4 . Consequently, the ZnIn 2 S 4 /g-C 3 N 4 composite exhibited enhanced visible light photocatalytic decomposition efficiency of 2,4-D, within 20% ZnIn 2 S 4 /g-C 3 N 4 composite owning the highest photocatalytic efficiency and initial rate. The initial rates of 2,4-D degradation on g-C 3 N 4 , ZnIn 2 S 4 , and 20% ZnIn 2 S 4 /g-C 3 N 4 were 1.23, 0.57 and 3.69   mmol/(g cat   h), respectively. The h + and O 2 − were found to be the dominant active species for 2,4-D decomposition. The photocatalytic degradation pathways of 2,4-D by ZnIn 2 S 4 /g-C 3 N 4 under visible light irradiation were explored. The ZnIn 2 S 4 /g-C 3 N 4 composite displayed high photostability in recycling tests, reflecting its promising potential as an effective visible light photocatalyst for 2,4-D treatment.