Study On The Improvement Of Photocatalytic Hydrogen Evolution Of G-CN By Annealing

As a two-dimensional photocatalyst,graphitic carbon nitride?g-CN?has been widely concerned by researchers in recent years.In this paper,we use a simple thermal strategy to prepare tri-s-triazine-based crystalline carbon nitride nanosheets?CCN-nanosheets?with a thickness from 2 to 5 nm via annealing.The number of amino groups in the as-obtained samples significantly decreases compared with the samples before treatment?bulk-CCN?,which optimizes the grain boundaries and narrows the band gap.Meanwhile,density functional theory?DFT?calculation demonstrates the distinct adjustment for the electronic structure of the sample from deamination.Combining the characteristics of two-dimensional morphology with high crystallinity,CCN-nanosheets demonstrates a high specific surface area of 154.2 m² g^-1,a suitable conductive band potential,improved photo-generated electron-hole pairs separation rate and high carrier transport efficiency.As a consequence,CCN-nanosheets exhibits an outstanding hydrogen evolution rate of 203?mol h^-1?18 times higher than that of bulk-CCN?and excellent cycling stability.It is anticipated that this facile and effective strategy for tailoring nanostructure and grain boundary would open up a new way for improving the photocatalytic performance of g-CN.