Highly enhanced photocatalytic hydrogen evolution activity of graphitic carbon nitride with 3D connected mesoporous structure

In this report, we demonstrate on the preparation of mesoporous graphitic carbon nitride (gCN) with 3D porous structure using dicyandiamide as a CN precursor and KIT-6 as a template via hard-template replication method and its superior photocatalytic hydrogen evolution activity under simulated sunlight. The powder X-ray diffraction, nitrogen adsorption and near edge X-ray absorption fine structure (NEXAFS) results reveal that the prepared materials possess gCN crystal structure with ordered mesopores and a 3D porous structure and a high specific surface area (221 m²/g). UV–Vis and PL spectra show that the absorption edges of mesoporous gCNs are slightly blue-shifted and the PL intensity is remarkably suppressed. The photocatalytic hydrogen evolution activity of gCN-KIT-6 under solar simulated irradiation is 1.92 mmol·g⁻¹ h⁻¹ which is much higher than that of gCN with 2D mesoporous structure, gCN from silica nanoparticle and bulk nonporous gCN. This high photocatalytic activity of gCN-KIT-6 can be attributed to 3D structure and the retarded electron-hole recombination.