One-step hydrothermal synthesis of rhombohedral ZnIn2S4 with high visible photocatalytic activity for aqueous pollutants removal

The phase composition of photocatalyst has a substantial effect on its photocatalytic activity. In this work, the rhombohedral phase ZnIn2S4 was synthesized by a one-step hydrothermal method by using inexpensive Na2S as a sulfur source with the assistance of NaCl. The Na2S as the S source can promote the generation of rhombohedral ZnIn2S4, and the addition of NaCl enhances the crystallinity of the as-prepared rhombohedral ZnIn2S4. The rhombohedral ZnIn2S4 nanosheets had a narrower energy gap, more negative conductive band potential, and higher separation efficiency of photogenerated carriers relative to the hexagonal ZnIn2S4. The as-synthesized rhombohedral ZnIn2S4 exhibited high visible photocatalytic activity with removal efficiencies of 96.7% in 80 min for the methyl orange, 86.3% in 120 min for ciprofloxacin hydrochloride and nearly 100% in 40 min for Cr(VI).