Template-free synthesis of nanocage-like g-C3N4 with high surface area and nitrogen defects for enhanced photocatalytic H2 activity

Abstract

Nanocage-like 3D porous graphitic carbon nitride (g-C₃N₄) with a high surface area and nitrogen defects was successfully prepared via a novel, template-free, cost-effective and hydrothermal-copolymerization route. Compared with pristine g-C₃N₄, the synergetic effect of nitrogen vacancies combined with a nanocage-like structure endowed it with a broad visible-light-responsive range, more exposed active lateral edges and catalytically active sites, as well as efficient separation of photogenerated carriers. As a consequence, the modified g-C₃N₄ exhibited prominent photocatalytic performance in water splitting for the hydrogen evolution reaction under visible light illumination. The optimized photocatalyst (DCN-550) showed a maximum photocatalytic H₂ evolution rate of 92.57 μmol h⁻¹, almost 20.3 times higher than that of pristine g-C₃N₄. Moreover, a possible mechanism for the photocatalytic hydrogen evolution and nanostructure formation process based on the experimental results was proposed. The new growth strategy developed here could inspire similar attempts to modify novel visible-light-driven photocatalysts through nanostructure design.