Enhanced photocatalytic water splitting activity of carbon-modified TiO_2 composite materials synthesized by a green synthetic approach

摘要

We report a green and facile approach for the preparation of carbon-modified (C-modified) TiO_2 composite materials by hydrothermal synthesis followed by pyrolytic treatment. The resultant materials were characterized by powder X-ray diffraction (XRD), nitrogen phys-isorption studies, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). The photocatalytic performances of these materials were evaluated by calculating the amount of hydrogen evolved from the decomposition of water under solar simulated irradiation conditions. An improvement was achieved from no H2 evolution at all with the bare TiO_2, to an evolution of 0.21 mLg~(-1)h~1 from a composite material modified with an optimum carbon loading of 3.62%. These results suggested that the interaction of carbon with predominantly rutile form of TiO_2 can promote shallow trapping of photogenerated electrons in the oxygen vacancies. This phenomenon consequently enhances the photocatalytic activity by minimizing charge carrier recombination, a characteristic demonstrated by fluorescence quenching of the TiO_2 emission.