Facile synthesis of distinctive nitrogen defect-regulated g-C3N4 for efficient photocatalytic hydrogen evolution

Nitrogen defect engineering has been deemed to be a promising strategy to overcome the inherent shortcomings, i.e., sluggish charge separation and limited spectral response range, of g-C3N4 photocatalyst. Herein, the construction of nitrogen-deficient g-C3N4 has been developed via a simple approach of modulating the type of urea precursor. The experimental investigation and theoretical calculations reveal that this novel route endows g-C3N4 with distinctive nitrogen defects, accompanying the decreased bandgap and the formation of midgap states under the conduction band edge, thus remarkably broadening the visible-light harvesting capability. Furthermore, the N defect also results in enhanced electrical conductivity, which greatly improves the charge carrier transfer and separation for photoredox reaction. As a result, the novel g-C3N4, named DCN, delivers a significantly high visible-light-responsive H2 evolution rate of 6.0 mmol h-1 g-1 under visible light irradiation, which is more than 5 times higher than that of the g-C3N4 (CN) synthesized using the common urea precursor. This work opens a novel avenue to fabricate nitrogen defect-regulated g-C3N4 for highly efficient H2 evolution and must intrigue a new wave of research upsurge on this kind of photocatalyst.