Activation of graphitic carbon nitride by solvent-mediated supramolecular assembly for enhanced hydrogen evolution

Developing earth-abundant photocatalysts with high activity and long term-stability for solar-driven hydrogen evolution reaction (HER) is an old but still tough challenge in the photocatalytic water splitting. Despite the remarkable progress that has been made in the preparation and modification of graphitic carbon nitride (g-C3N4), the most popular metal-free photocatalyst, there still exists a need to explore novel synthetic approaches for the controllable synthesis of g-C3N4-based photocatalytic materials toward improved HER performance. Herein, we propose a solvent-mediated supramolecular assembly approach to fabricate modified g-C3N4 nanoarchitectures based on the asymmetric polymerization of three precursors, melamine, cyanuric acid and barbituric acid. The resulting g-C3N4 nanostructure assisted by the supramolecular preorganization of precursors is favorable for visible light harvesting, charge carrier separation and solar HER performance. The hydrogen-evolution rate of the modified g-C3N4 sample derived from ethanol is three times higher than that of g-C3N4 calcined from the symmetric polymerization of melamine and cyanuric acid, implying the important role of barbituric acid. More importantly, the effects of solvent polarity on the morphology, composition, charge carrier dynamics and HER activity were evaluated.