A Copper(I) Telluride–Graphitic Carbon Nitride Heterostructure with p-Type Conductivity for Photocatalytic Hydroxyl Radical Generation and Hydrogen Evolution Reactions

There is a growing demand for developing sustainable materials for environmental cleanup and clean energy generation. p-Type Cu 2 Te nanorods are synthesized by surface modification with g-C 3 N 4 (denoted Cu 2 Te/g-C 3 N 4 ). The material is thoroughly characterized to elucidate its structure, morphology, chemical composition, band gap, surface defects, band position, and conductivity type. The optimized batch of Cu 2 Te/g-C 3 N 4 was revealed to be an excellent source of photocatalytic hydroxyl radicals, corroborated by the radical trapping method monitored by photoinduced electron paramagnetic resonance (EPR). The hydroxyl radical generation by Cu 2 Te/g-C 3 N 4 accounted for the photocatalytic degradation of methylene blue (MB) (a model dye), i.e., 97% degradation in 80 min ( k = 0.043 min –1 ). The photocatalytic degradation mechanism is discussed, including favorable band alignments in the heterostructure of Cu 2 Te/g-C 3 N 4, charge transfer, reactive oxygen species (ROS) generation, and identification of degradation intermediates. In addition, Cu 2 Te/g-C 3 N 4 exhibits a low overpotential for an alkaline hydrogen evolution reaction (HER) (η 10 = 107 mV). It is attributable to higher surface active sites due to surface modification by g-C 3 N 4 that favors adsorption/desorption of hydrogen intermediates, favorable wettability, lower charge transfer resistance, and faster charge kinetics (Tafel slope = 33.5 mV dec –1 ), high mass activity (6.13 A/g), and a specific activity of 0.024 mA/cm 2 at an overpotential of 200 mV.