Hydrogen-assisted Synthesis of Defective Triazine/heptazine Homostructured Nanosheets for Efficient CO Photoreduction.

Homostructure construction has been proven to be an effective method for boosting the photocatalytic activity of polymeric carbon nitride. However, the contribution of the intrinsic activity of molecular fragments in the catalytic performance of homostructured carbon nitride is yet to be explored. In this paper, a facile hydrogen-assisted strategy was used to synthesize triazine/heptazine intermolecular homojunctions (g-CN(MU-H)) with an ultrathin and defective structure, via the co-pyrolysis of melamine and urea precursors. Experimental characterizations and theoretical calculations indicated the copolymerization of triazine- and heptazine-based carbon nitride generated a homostructured interface with a large build-in electric field for efficient separation of photogenerated carriers. Owing to the synergestic effect between the homostructured interface and nitrogen vacancies, as-synethesized g-CN(MU-H) exhibited an outstanding activity for photocatalytic CO reduction, with 14.45 μmol h CO yield, which was 23.5 and 3.64 times higher than those of bulk g-CN and g-CN(M-H) synthesized from a single precursor, respectively. In this study, We provided a novel route for optimizing the charge separation efficiency of CO photoreduction catalysts by constructing intramolecular homojunction.