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 Cu2Te nanorods are synthesized by surface modification with g-C3N4 (denoted Cu2Te/g-C3N4). 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 Cu2Te/g-C3N4 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 Cu2Te/g-C3N4 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 Cu2Te/g-C3N4, charge transfer, reactive oxygen species (ROS) generation, and identification of degradation intermediates. In addition, Cu2Te/g-C3N4 exhibits a low overpotential for an alkaline hydrogen evolution reaction (HER) (η10 = 107 mV). It is attributable to higher surface active sites due to surface modification by g-C3N4 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/cm2 at an overpotential of 200 mV.