Enhanced photocatalytic water splitting activity of carbon-modified TiO2 composite materials synthesized by a green synthetic approach.

We report a green and facile approach for the prepn. of carbon-modified (C-modified) TiO2 composite materials by hydrothermal synthesis followed by pyrolytic treatment. The resultant materials were characterized by powder X-ray diffraction (XRD), nitrogen physisorption studies, Raman spectroscopy, XPS, diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM). The photocatalytic performances of these materials were evaluated by calcg. the amt. of hydrogen evolved from the decompn. of water under solar simulated irradn. conditions. An improvement was achieved from no H2 evolution at all with the bare TiO2, to an evolution of 0.21 mL g-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 TiO2 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 TiO2 emission. [on SciFinder(R)]