Mechanism insight into enhanced photocatalytic hydrogen production by nitrogen vacancy-induced creating built-in electric field in porous graphitic carbon nitride nanosheets

We purposefully develop a precursors-reforming strategy to exquisitely introduce an appropriate amount of N vacancies in the conjugation plane of porous g-C3N4 nanosheets. Most importantly, the mechanism for enhancing photocatalytic hydrogen evolution by the vacancy-induced generation of a built-in electric field is profoundly revealed. [Display omitted] •Porous g-C3N4 with moderate N vacancies is obtained by precursor-reforming strategy.•N vacancies facilitate the enhancement of built-in electric fields between melons.•Synergy of built-in electric fields, textures, and reaction kinetics improves HER.•Performance enhancement mechanisms are insightfully elucidated. An appealing and efficient route to modify the catalytic behavior of g-C3N4 (gCN) is to control textures and defects at the molecular scale, which is beneficial to enhancing its built-in electric field (BIEF) and accelerating the photogenerated charge carrier separation. Herein, we deliberately design a precursors-reforming strategy for enhancing the BIEF of gCN porous microstructures through constructing N vacancies to accelerate charge separation. The N vacancies can not only enhance the BIEF, thus accelerating photocharge delocalization, but also promote reaction kinetics. Also, the porous structures offer a large number of active sites to expedite the reaction and shorten the migration distance of photogenerated carriers to the surface. As anticipated, the modified gCN exhibits a much higher photocatalytic performance, around 7.1 times that of the bulk gCN. This work will provide a fascinating method to combine textures and electronic structure regulation for gCN-based photocatalysts.