Exogenous inorganic anions assisted the transformation and formation of cubic ZnIn2S4 with excellent photocatalytic properties

Inorganic anions have a significant impact on the crystal structure of ZnIn2S4 due to their electronegativity and polarity. Using ZnSO4 and In(NO3)3 as metal precursors, the transformation of ZnIn2S4 from hexagonal to cubic phase and the controllable growth of active crystal plane achieved under simple experimental operation. The crystal structure, surface functional groups, morphology and physicochemical properties of the as-prepared materials were analyzed using modern instrument characterization techniques. In addition, tetracycline hydrochloride (HTC) and Cr(VI) solution were used as target pollutants to evaluate the photocatalytic performance of the materials, and the results showed that the higher relative content ratio of (311) crystal plane made the cubic ZnIn2S4 have better photocatalytic performance, that is, the photocatalytic activity of ZnIn2S4-pHH2SO4 was better, with the removal rates of HTC and Cr (VI) reaching 89.50 % and 98.21 %, respectively. Furthermore, EIS and Tafel curves indicated that ZnIn2S4-pHH2SO4 had a higher separation efficiency of photogenerated electrons and holes, and free radical capture experiments and EPR spectra showed that ·O2- and h+ were the main active species in the photocatalytic degradation of HTC, which establishes the relationship between the structure and properties of the material. The intermediates and possible degradation pathways of HTC were analyzed by 3D-EEM and LC-MS, and the photocatalytic degradation mechanism of HTC by ZnIn2S4-pHH2SO4 was proposed.