One-dimension TiO2 nanostructures with enhanced activity for CO2 photocatalytic reduction

Abstract

The one dimension (1D) TiO2 nanotubes and nanorods were successfully prepared via a one-step hydrothermal method. The structure and properties of the catalysts were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Electron paramagnetic resonance (EPR), N2 adsorption-desorption, UV–vis diffuse reflectance and photoluminescence (PL) spectroscopy. Meanwhile, the photoelectrochemical properties were recorded through Mott-Schottky, transient photo-current responses and electrochemical impedance spectroscopy curves (EIS). The results showed that 1D TiO2 nanostructures catalysts had a high specific surface area, enhanced visible light response and superior electron transport properties. The photocatalytic activities of catalysts for reduction CO2 were investigated under 9 h irradiation of a 300 W Xe arc lamp equipped with UV 420 nm bandpass filter. The maximum yields of CH4 over the TiO2 nanotubes (TNT) and TiO2 nanorods (TNR) were 19.16 μmol/g.cat and 12.71 μmol/g.cat, respectively, which were approximately 2.33 folds and 1.48 folds higher than TiO2 nanoparticles (TNP). The enhanced photocatalytic activity of TiO2 nanotubes and nanorods could be ascribed to the presence of oxygen vacancies and defects formed during the calcination process and its special structures, which accelerates the transfer of electrons. Besides, the better activity of TNT than TNR may be ascribed to its unique hollow tubular structure and larger surface area.