Morphology-effects of four different dimensional graphitic carbon nitrides on photocatalytic performance of dye degradation, water oxidation and splitting

Graphitic carbon nitride (g-C3N4), as a new metal-free photocatalyst, has attracted more and more concerns in visible-light-driven photocatalysis field, because of its band gap at 2.70 eV which makes its absorption be in the visible range, and its unique structure which results in excellent photocatalytic performance. Not only the micro network structure of carbon nitride, but also its macro material morphology plays a key role in its photocatalytic performance. Herein, in order to compare the photocatalytic activity of various morphologies, four different g-C3N4 with bulky, spherical, flaky and tubular morphologies were prepared respectively by hydrothermal, solvothermal and thermal polymerization methods. The physical and photophysical properties of these g-C3N4 photocatalysts were characterized, and the effect of g-C3N4 morphology on the photocatalytic activity was investigated. The results showed that flaky g-C3N4 had the highest photocatalytic activity for the degradation of organic dyes such as MB, MO, and Rh B. While its photocatalytic oxygen reduction for H2O2 production and the photocatalytic water splitting for hydrogen evolution reached 3093 μmol g−1 h−1 and 1276 μmol g−1 h−1, respectively, which were better than those of the other three g-C3N4 morphologies. [Display omitted] •Four morphologies of g-C3N4 (BCN, FCN, SCN and TCN) were synthesized by different stretagies.•The band gaps of BCN, FCN, SCN and TCN were determinated by DFT calculations from DRS data.•Morphology-effects of 4 CNs on photodegradation of dyes, H2 and H2O2 evoluation were compared.•Under same conditions, FCN exhibited the most enhanced photocatalytic activity among the four.