GRAPHITIC CARBON NITRIDE MODIFIED BY SILICON FOR IMPROVED VISIBLE-LIGHT-DRIVEN PHOTOCATALYTIC HYDROGEN PRODUCTION

摘要

In this work, composites of silica and graphitic carbon nitride (g-C_3N_4) were conveniently synthesized through polymerization of melamine and ethyl silicate. Some basic physicochemical properties of these metal-free photocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), Fourier transform infrared spectrometer (FTIR) spectra, transmission electron microscope (TEM), UV-visible diffuse reflectance spectrum and N_2 adsorption-desorption measurement. The XRD patterns of all the prepared materials were dominated by the characteristic (002) peak at 27.5° of a graphitic structure, indicating that the induced Si did not destroy the crystal structure of g-C_3N_4. As the initial molar ratio of Si to C increased, enhanced photocatalytic activity was observed for H_2 evolution from a triethanolamine aqueous solution under visible-light irradiation over the series of composites. It was proved that the introduction of Si resulted in large surface area, which is favorable for reactant-transfer and charge-migration, beneficial for photocatalysis.