Synthesis of AgBr/Ti₃C₂@TiO₂ ternary composite for photocatalytic dehydrogenation of 1,4-dihydropyridine and photocatalytic degradation of tetracycline hydrochloride

In this work, AgBr/Ti3C2@TiO2 ternary composite photocatalyst was prepared by a solvothermal and precipitation method with the aims of introducing Ti3C2 as a cocatalyst and TiO2 as a compositing semiconductor. The crystal structure, morphology, elemental state, functional groups and photoelectrochemical properties were studied by XRD, SEM, TEM, XPS, FI-IR and EIS. The photocatalytic performances of the composites were investigated by the photodehydrogenation of diethyl 1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate (1,4-DHP) and the photodegradation of tetracycline hydrochloride (TCH) under visible light irradiation (& lambda; > 400 nm). The AgBr/Ti3C2@TiO2 composite photocatalyst showed enhanced photocatalytic performance in both photocatalytic reactions. The photocatalytic activity of the composite photocatalyst is dependent on the proportional content of Ti3C2@TiO2. With optimized Ti3C2@TiO2 proportion, the photocatalytic ability of the AgBr/Ti3C2@TiO2 composite was 24.5 times as high as that of Ti3C2@TiO2 for photodehydrogenation of 1,4-DHP and 1.9 times as high as that of pure AgBr for photodegradation of TCH. The enhanced photocatalytic performance of the AgBr/Ti3C2@TiO2 composite should be due to the formation of a p-n heterojunction structure between AgBr and Ti3C2@TiO2 and the excellent electronic properties of Ti3C2, which enhanced the visible light absorption capacity, lowered the internal resistance, speeded up the charge transfer and reduced the recombination efficiency of photo-generated carriers. Mechanism studies showed that superoxide free radical (O-2(-)) was the main active species. In addition, the composite photocatalyst also displayed good stability, indicating its reutilization in practical application.