Electrostatically assembled construction of ternary TiO2-Cu@C hybrid with enhanced solar-to-hydrogen evolution employing amorphous carbon dots as electronic mediator

The huge demand for renewable hydrogen produced by water splitting has prompted people to conduct in-depth research on the hydrogen evolution reaction for the development of earth-abundant, non-precious, and multi-functional metal catalysts. Herein, a noble-metal-free ternary composite of TiO2-Cu@C was prepared by electrostatic self-assembly loaded copper nanoparticles and amorphous carbon dots (CDs) on porous TiO2 microrods. The good conductivity of the CDs was beneficial to promoting the charge transfer and separation, generating an enhanced solar-to-hydrogen performance on TiO2-Cu@C. The optimized TiO2-Cu@C reveals a stable and notable hydrogen evolution rate of 3911 μmol g−1h−1, which is 1.6 times that of TiO2-Cu and many times higher than that of TiO2. Instead of providing active sites for hydrogen production, the CDs act as an electronic mediator and provide another electron pathway to further enhance the activity of TiO2-Cu, where the photogenerated electrons on TiO2 could pass through the CDs to the copper cocatalyst and reduce water to hydrogen.