Highly efficient photocatalytic degradation of different hazardous contaminants by CaIn2S4-Ti3C2Tx Schottky heterojunction: An experimental and mechanism study

[Display omitted] •Ti3C2Tx MXene acts as cocatalyst for tetracycline hydrochloride degradation and Cr (VI) reduction.•High charge separation efficiency is achieved by introducing the Ti3C2Tx.•Enhanced visible light harvesting and Schottky junction result in enhanced photocatalytic performance.•The photogenerated h+, ·O2− and e− dominate the degradation and reduction process. The low charge transfer efficiency of isolated semiconductors is an urgent challenge in the photocatalytic degradation of hazardous contaminants. In this work, CaIn2S4/MXene Ti3C2Tx Schottky heterojunctions are synthesized via a simple hydrothermal method and applied for tetracycline hydrochloride degradation and Cr(VI) reduction. Results show that Ti3C2Tx as a cocatalyst can limit the charge recombination and boost the absorption of visible light, thus promoting the photocatalytic efficiency of pure CaIn2S4. An optimized CaIn2S4-Ti3C2Tx hybrid has the highest catalytic rate in the degradation of tetracycline hydrochloride (96%) and reduction of Cr(VI) (98%). Studies probing the mechanism indicate that the photogenerated superoxide radicals and holes play a key role in the tetracycline hydrochloride degradation process, while electrons are core to the Cr(VI) reduction reaction. Besides the high photocatalytic efficiency, the CaIn2S4-Ti3C2Tx hybrids also exhibit outstanding photo-stability in the present conditions, suggesting the potential for practical use.