One-step synthesis of few layers g-C3N4 with suitable band structure and enhanced photocatalytic activities

[Display omitted] •A self-exfoliation process based on heating melamine and urea is reported.•Two few layers g-C3N4 samples (M-CN and U-CN) are obtained, respectively.•The conductive band bottom of M-CN is significantly lower than that of U-CN.•The hydrogen evolution rate of M-CN is 37 times than that of the bulk g-C3N4.•The obtained M-CN exhibits much higher hydrogen evolution rate than that of U-CN. We report a one-step process to prepare high activity few-layers g-C3N4 by a self-exfoliated method. Two kinds of few layers materials are obtained from heating melamine (M-CN) and urea (U-CN), respectively. Although both materials exhibit similar high specific surface area, the conductive band position of M-CN (−1.89 eV) is obviously lower than U-CN (−1.45 eV). As a result, the M-CN sample exhibits a much higher hydrogen evolution rate than U-CN. Remarkably, the hydrogen evolution rate of M-CN is 37 higher than the bulk. Our results provide a new strategy for the preparing few-layers g-C3N4 for high photocatalytic performance.