Carbon Nitride (C_3N_4) Photocatalysts Synthesized from Different Methods for Photocatalytic Reaction Under Visible Light Irradiation

摘要

C_3N_4 have generally been synthesized with a solid-state(SS) method, which formed a graphitic feature with tri-s-triazine(C_6N_7) units. This study reports a solvothermal(ST) synthesis, in which the powders were obtained as low as 150-220 °C. X-ray diffraction analyses showed that the crystalline structure of ST changed from pseudocubic- to beta-C_3N_4 with increasing the solvothermal temperature, and C_3N_4 obtained from SS method displayed a graphitic structure with diffraction angles at 13.1° and 27.5°. The diffraction angles represented (100) plane of tri-s-triazine units and (002) plane of stacking of the conjugated-aromatic system, respectively. UV-Vis absorbance spectra showed that the band gap of SS was 2.6 eV, and that of ST samples were 1.9-2.45 eV. To evaluate the visible-light responded photocatalytic activity of the samples, degradation of methylene orange dyes was conducted. ST revealed a higher photo-activity, which result from its larger light absorbance in the visible regime compared to that of SS ones.