Self-assembled 3D hollow carbon nitride with electron delocalization for enhanced photocatalytic hydrogen evolution

For the first time in this work, three-dimensional hollow carbon nitride (SA-3DCN) with unique electron delocalization feature was prepared by introducing salicylic acid (SA) into the hydrothermal process of melamine (M) and cyanuric acid (CA). The aromatic ring structure of SA imbedded into the structure of g-C₃N₄ could not only adjust its energy band structure and extend the optical absorption, but also trap photogenerated electron and enhance the charge separation efficiency. Besides, the hollow three-dimensional structure made the active sites well and evenly dispersed. Thus the photocatalytic hydrogen production rate of SA-3DCN-1.0 was significantly enhanced, up to 1.52 mmol h⁻¹ g⁻¹, 110 folds higher than that of pristine g-C₃N₄. This work offers a creative thought to regulate the delocalized π electrons of multidimensional hollow semiconductors to enhance the photocatalytic hydrogen production.