Highly Conjugated Graphitic Carbon Nitride Nanofoam\nfor Photocatalytic Hydrogen Evolution

Abstract

As\na metal-free photocatalyst, graphitic carbon nitride (g-CN)\nshows great potential for photocatalytic water splitting, although\nits performance is significantly limited by structural defects due\nto incomplete polymerization. In the present work, we successfully\nsynthesize highly conjugated g-CN nanofoam through an iodide substitution\ntechnique. The product possesses a high polymerization degree, low\ndefect density, and large specific surface area; as a result, it achieves\na hydrogen evolution rate of 9.06 mmol h^–1 g^–1 under visible light irradiation, with an apparent\nquantum efficiency (AQE) of 18.9% at 420 nm. Experimental analysis\nand theoretical calculations demonstrate that the recombination of\nphotogenerated carriers at C–NH_<i>x</i> defects was effectively depressed in the nanofoam, giving rise to\nthe high photocatalytic activity.