Synthesis of TiO2/Ti3C2T /AgI Z-scheme photocatalyst for tetracycline hydrochloride photocatalytic degradation

A ternary composite photocatalyst with high catalytic activity (TiO2/Ti3C2Tx/AgI) was synthesized using the simple solvothermal and coprecipitation methods. The structure, morphology, photoelectric properties, and photocatalytic activity of the prepared materials were studied using various characterization techniques. The composite catalysts TiO2/Ti3C2Tx/AgI with different proportions of TiO2/Ti3C2Tx to AgI of 10%, 20%, 50%, 70%, and 90% were prepared by varying the amounts of AgNO3 and KI. Compared to AgI and TiO2/Ti3C2Tx, TiO2/Ti3C2Tx/AgI demonstrated a superior photocatalytic degradation activity for tetracycline hydrochloride (TCH) under simulated sunlight. The degradation rate of TCH with 70% TiO2/Ti3C2Tx/AgI composite photocatalyst reached 97%. The photoluminescence (PL) emission spectra showed that the recombination of photogenerated electrons of 70% TiO2/Ti3C2Tx/AgI was effectively inhibited after the formation of AgI, TiO2, and Ti3C2Tx heterojunctions. The electrochemical impedance spectroscopy (EIS) indicated that a rapid interfacial charge transfer of the 70% TiO2/Ti3C2Tx/AgI composite to the electron acceptors (Ti3C2Tx). Ti3C2Tx had high conductivity and can effectively accelerate the transfer and separation of photogenerated carriers as a charge medium. Therefore, the enhancement of photocatalytic activity of TiO2/Ti3C2Tx/AgI can be attributed to the Z-scheme heterojunction with non-metal Ti3C2Tx as the solid medium. In addition, the trapping agent experiment showed that superoxide radicals, singlet oxygen, and holes were the main active substances in the photocatalytic degradation of TCH by the TiO2/Ti3C2Tx/AgI composite.