Microwave-assisted synthesis of RuTe2/black TiO2 photocatalyst for enhanced diclofenac degradation: Performance, mechanistic investigation and intermediates analysis

Abstract Seeking active and low-cost cocatalysts is a vital task for solving the sluggish kinetics of photocatalysis process in environmental management. Herein, we report a novel and high-efficiency crystallized RuTe2 cocatalyst, and loaded it onto black TiO2 to form photocatalytic heterostructure (denoted as RuTe2/B-TiO2) for diclofenac (DCF) degradation. To the best of our knowledge, the RuTe2 as a cocatalyst for photocatalysis based on swift electron capture has not been documented yet. The degradation efficiency of DCF over 0.5% RuTe2/B-TiO2 reached 95.2% for 120 min, which is 1.2 times higher than that of pure B-TiO2. In addition, the effects of different calcination temperatures, catalyst amounts, DCF concentrations and solution pH of the as-prepared catalysts were also investigated in depth. Spectroscopy/electrochemistry showed that 0.5% RuTe2/B-TiO2 exhibited a narrower band gap, more active sites and better electrical conductivity than pure B-TiO2. Experiments with trapping agents have shown that •O2- was the main active substance under irradiation. Furthermore, intermediates for the photodegradation of DCF were detected by liquid chromatography mass system (LC-MS) and density functional theory (DFT) calculations. Finally, the degradation pathway was rationalized and a possible photocatalytic mechanism for 0.5% RuTe2/B-TiO2 was proposed.