Photocatalytic hydrogen generation using a nanocomposite of multi-walled carbon nanotubes and TiO2 nanoparticles under visible light irradiation

Nanocomposite catalysts (MWNT-TiO2) were prepared hydrothermally from multi-walled carbon nanotubes (MWNTs) and titanium sulfate as the titanium source, and then systematically analyzed using electron microscopy, Raman, FT-IR, and UV-vis spectroscopy. Pt-loaded nanocomposites, pristine TiO2 and MWNTs were examined for their photocatalytic activity on splitting water with triethanolamine as an electron donor. Under visible light irradiation (lambda > 420 nm), hydrogen was successfully produced over the Pt/MWNT-TiO2, while no capacity to split water showed on the Pt-loaded pristine TiO2 and MWNTs. Under full spectral irradiation of a Xe-lamp, a hydrogen generation rate of up to 8 mmol g(-1) h(-1) or more was achieved. The significant photocatalytic activity of the nanocomposites was attributed to the synergetic effect of the intrinsic properties of its components such as an excellent light absorption and charge separation on the interfaces between the modified MWNTs and TiO2, resulting from direct growth of TiO2 nanoparticles on the surface of the MWNTs during the hydrothermal process.