Template-free synthesis of a novel porous g-C3N4 with 3D hierarchical structure for enhanced photocatalytic H2 evolution

• Porous g-C3N4 with 3D hierarchical structure was prepared by a temple-free method.
• Porous g-C3N4 features large surface area and low charge carrier recombination.
• Porous g-C3N4 exhibits superior visible-light photocatalytic H2-evolution activity.

Porous graphitic carbon nitride (g-C3N4) with three-dimensional (3D) hierarchical structure was fabricated via a template-free approach by using cyanuric acid as a polymerization inhibitor. The hierarchical porous structure has a remarkable effect on the surface properties and photocatalytic performance of g-C3N4 for photocatalytic H2 production under visible light irradiation (λ >420 nm). The photocatalytic H2-evolution rate over the hierarchical porous g-C3N4 is 68.5 μmol/h, which is about 4.8 times higher than that of pristine g-C3N4. Characterization results show that the formation of the 3D hierarchical porous structure results in the enlarged specific surface area, enhanced redox potential, and decreased recombination of photoinduced charge carriers of g-C3N4, contributing to the enhanced photocatalytic activity.