Disordered nitrogen-defect-rich porous carbon nitride photocatalyst for highly efficient H2 evolution under visible-light irradiation

Precursor types play crucial factors for synthesizing high-efficiency graphitic carbon nitrides (GCNs). Herein, biuret was employed as a new precursor to prepare a disordered nitrogen-defect-rich porous GCN (BCN). The crystallinity, structure and performance properties for BCN were explored by making systematic comparisons with other commonly available GCNs which were derived from conventional precursors under the identical conditions. Biuret could be the optimal choice for the preparation of high-performance GCN according to the reports so far. BCN not only possessed long-range atomic disordered structure, but also contained numerous nitrogen defects embedded into the in-planes of the disordered GCN networks, leading to extended visible-light absorption (absorption edge at 525 nm), improved separation of photoexcited charge carriers, and rich available reactive sites. The large surface area and high porosity of BCN also provided plenty of reactive sites. Consequently, ultrahigh photocatalytic H2 production and excellent O2 production performance were achieved for BCN, the AQY for H2 production achieved 45.5% at 420 nm, which was one of the highest values for GCN-based photocatalysts. [Display omitted] •Graphitic carbon nitride was prepared by direct thermal polymerization of a kind of new precursor–biuret.•Biuret-derived graphitic carbon nitride (BCN) possessed disordered structure with nitrogen vacancies and cyano groups.•BCN behaved favorable visible-light absorption ability with the absorption edge at about 525 nm, the bandgap was 2.45 eV.•BCN behaved ultrahigh photocatalytic H2 production performance, and the AQY achieved 45.5% at 420 nm.