Preparation of Carbon Self-Doping Graphic Carbon Nitride Nanosheets for Photocatalytic H2 Evolution Performance under Visible-Light Irradiation

The photocatalytic activity of graphic carbon nitride (g-C3N4) was limited because of poor visible-light utilization and low photogenerated carriers separation. Herein, carbon self-doping g-C3N4 (CNNS-x, x mg represents the mass of TAPD in precursor) was simply prepared by one-step thermal co-polymerization of the homogeneous mixture of urea and 2,4,6-triaminopyrimidine (TAPD). The as-prepared CNNS-x was carefully characterized by powder X-ray diffraction (XRD), elemental analysis (EA), and X-ray photoelectron spectroscopy (XPS), which indicated that the pyrimidine was incorporated into the pi-conjugated graphic carbon nitride. Thus, the CNNS-x was endowed with narrower bandgap, higher electric conductivity, which are favorable for improving the efficiency of visible-light absorption and photogenerated carrier separation. As a consequence, all the CNNS-x show remarkably improved performance in photocatalytic hydrogen evolution activity under visible-light irradiation. The optimum sample (CNNS-30) showed an excellent hydrogen evolution rate (similar to 57 mu mol.h(-1)), which was up to 4 times higher than that of g-C3N4 nanosheets (CNNS).