Nitrogen defects-rich porous graphitic carbon nitride for efficient photocatalytic hydrogen evolution.

Graphitic carbon nitride (CN) is considered as a promising photocatalyst for solar energy conversion. However, low specific surface area and fast electrons and holes recombination restrict the photocatalytic applications of CN material. Herein, a nitrogen defect-rich and highly porous CN nanostructure (CN-LT) was prepared by combining two strategies, i.e., LiOH treatment and heat etching. The as-prepared nitrogen defect-rich porous CN-LT not only has a larger specific surface area, as compared with pristine CN, but also the photogenerated electron-hole separation was boosted remarkably. Using Pt as a co-catalyst and lactic acid aqueous solutions as sacrificial reagent under visible light irradiation (λ > 400 nm), the hydrogen evolution reaction (HER) rate for CN-LT (1.54 mmol h g) was 19.25 times higher than that for pristine CN (0.08 mmol h g). While subjecting pristine CN to heat etching under the same experimental conditions, excepting the use of LiOH (CN-T), an increase in HER rate of 7.5 times was obtained. Our current study may shed more light on the enhancement of the photocatalytic activity of bulk CN materials by altering their microstructure.