Processing graphitic carbon nitride for improved photocatalytic activity

In order to improve the photocatalytic activity of graphitic carbon nitride (g-C3N4), the as-prepared samples were processed by acid etching followed by thermal treatment. The specific surface area of the g-C3N4 increased from 11.5 to 81.5 m2/g, and many mesoporous pores were formed after hydrothermal and thermal treatment. Compared with the as-prepared g-C3N4, the photocatalytic activity of the treated g-C3N4 photocatalysts is significantly enhanced towards the degradation of RhB under visible light irradiation. The kinetic rate constant of the treated g-C3N4 is 6.3 times of that of the pristine g-C3N4. The enhancement of the photocatalytic activity of the catalysts can be ascribed to their improved specific surface area and the N-vacancy in g-C3N4. The N-vacancy in the structure of g-C3N4 decreases the bandgap of carbon nitride, thus enhances the visible light absorption. The higher specific surface area of the treated g-C3N4 enhances the adsorption towards RhB, and provides more active sites as well, thus higher photocatalytic activity was achieved.