Highly efficient photocatalytic degradation of different hazardous contaminants by CaIn₂S₄-Ti₃C₂T_x Schottky heterojunction: An experimental and mechanism study

The low charge transfer efficiency of isolated semiconductors is an urgent challenge in the photocatalytic degradation of hazardous contaminants. In this work, CaIn₂S₄/MXene Ti₃C₂T_x Schottky heterojunctions are synthesized via a simple hydrothermal method and applied for tetracycline hydrochloride degradation and Cr(VI) reduction. Results show that Ti₃C₂T_x 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-Ti₃C₂T_x 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-Ti₃C₂T_x hybrids also exhibit outstanding photo-stability in the present conditions, suggesting the potential for practical use.