Phenyl-incorporated carbon nitride photocatalyst with extended visible-light-absorption for enhanced hydrogen production from water splitting

Developing and employing photocatalysts with extended visible-light-absorption has emerged as a fundamental issue for the enhanced capability of photocatalytic H₂ evolution from water splitting. Herein, a wide-spectrum light-responsive phenyl-grafted carbon nitride photocatalyst was synthesized. It was found that benzonquanmine-derived g-C₃N₄ (BCN) exhibits significantly extended light absorption (∼670 nm) compared with conventional melamine-derived g-C₃N₄ (MCN). Correspondingly, the photocatalytic H₂-evolution rate of BCN (2846 μmol h⁻¹ g⁻¹) is five times as that of MCN under visible-light irradiation. Particularly, an impressive H₂-evolution rate of 58 μmol h⁻¹ g⁻¹ could be achieved on BCN even under light irradiation beyond 620 nm. The outstanding photocatalytic H₂-evolution performance could be not only attributed to the enriched photons generated from the enhanced solar energy harvesting, but also to the distinctly inhibited rapid recombination of photogenerated electron-hole pairs resulting from the incorporation of phenyl groups. This work furnishes a new train of thought for the designing of carbon-nitride-based photocatalysts with enhanced capability of visible-light-utilization.