Preparation And Performance Of Mesoporous TiO₂-based Composites

Mesoporous TiO₂ nanotubes and Co-doped TiO₂ nanotubes were prepared using poly?ethylene-glycol?-Block-poly?propy-glycol?-block-poly?ethylene-glycol?as a soft template,TiOSO₄ as titanium precursor through a simple solvothermal route.A series of mesoporous TiO₂ nanotubes /reduced graphene oxide?RGO?and Co-doped TiO₂ nanotubes/RGO composites were synthesized via a hydrothermal method.In this method,graphene oxide?GO?was reduced to RGO,whereas GO were prepared using a modified Hummer's method.Their morphology and properties were determined using atomic force microscope,field emission scanning electron microscopy,transmission electron microscope,X-ray diffraction,UV-vis diffuse reflectance spectra,and Raman measurement.Results indicated that TiO₂ NT displayed tubular mesoporous structures with lengths ranging from about 3 ?m to 10 ?m,tube diameters ranging from about 400 nm to 600 nm,wall thickness of about 250 nm,and mesoporous walls of about 6 nm.The photocatalytic properties of TiO₂ nanotubes and Co-doped TiO₂ nanotubes were tested with papermaking wastewater under UV illumination.TiO₂ nanotubes and show an excellent performance in the removal of chroma.Co-doped TiO₂ nanotubes exhibited higher photocatalytic efficiency in chemical oxygen demand?CODCr?after Co doping.The removal of CODCr of sample Co-TiO₂-2 were about 94.98% after 12 h of photodegradation.The electrochemical performance of the TiO₂-based electrodes for supercapacitor was confirmed by cyclic voltammetry,electrochemical impedance spectroscopy,and galvanostatic charge–discharge in 0.50 mol L-1 Na₂SO₄ aqueous electrolyte solution.The Co-doped TiO₂NT/RGO composite electrode with 10.00 wt.% GO exhibited a specific capacitance of 27.50 Fg^-1 at a current density of 0.2 Ag^-1 in a symmetrical two-electrode cell,whereas the specific capacitance of TiO₂ was 0.70 Fg^-1.The Co-doped TiO₂NT/RGO composite electrode showed high rate capability and excellent long-term cycle stability.The outstanding performance of the Co-doped TiO₂NT/RGO composite electrode was attributed to the synergistic effects on capacitive behavior of Co-doped TiO₂ NT combined with high electronic conductivity of the RGO sheets.