Rich carbon vacancies facilitated solar light-driven photocatalytic hydrogen generation over g-C3N4 treated in H2 atmosphere
Youmei Li, Junbo Zhong, Jianzhang Li, Jianzhang Li
Abstract
Graphite carbon nitride (g-C 3 N 4 ) has caught far-ranging concern for its masses of advantages, for instance, the unique graphite-like two-dimensional lamellar structure , low cost, nontoxic, suitable bandgap of 2.7 eV and favorable stability. Whereas owing to the shortcomings of low solar absorptivity and fast recombination of photo-induced charge pairs, the overall quantum efficiency of photocatalysis for g-C 3 N 4 is suboptimal, resulting in limited practicality of g-C 3 N 4 (GCN). In our study, modified g-C 3 N 4 materials (HCN) with ample carbon vacancies (CVs) were obtained through calcinating of g-C 3 N 4 in H 2 atmosphere. Higher specific surface area and more active sites of HCN were induced by roasting of g-C 3 N 4 in H 2 . CVs that occurred in the N-(C 3 ) bond lead to the reduction of electron density around N, thus narrowing the bandgap of HCN-3h and enlarging corresponding light response capability. Under the synergistic function of abundant pore construction and CVs on HCN, the photo-excited e − /h + pairs can be memorably separated and transferred, which is favorable to photocatalytic efficiency. Among HCN, the HCN-3h sample has the highest H 2 generation rate of 4297.9 μmol h −1 g −1 , which achieves 2.3-fold higher than that of GCN (1291.7 μmol h −1 g −1 ). This paper brings forward a meaningful method of boosting the photocatalytic performance of photocatalysts by constructing abundant CVs.