Roles of Vanadium and Nitrogen in Photocatalytic Activity of VN-Codoped TiO2 Photocatalyst

Cu/N-codoped TiO2 prepared by the sol-gel method for phenanthrene removal under visible light irradiation

Cu/N-codoped TiO₂ nanoparticles were prepared by the modified sol-gel method, to study its efficiency for the removing of polyaromatic hydrocarbon (phenanthrene) from an aqueous solution. Urea and copper sulfate pentahydrate were used as sources of doping element for Cu/N-codoped TiO₂, respectively. The characterizations of the nanoparticles were done by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra. XRD revealed that all the nanoparticles were indexed to the anatase phase structure, with crystallite size range from 11 to 30 nm, which decreased with the doping of copper and nitrogen. The photocatalytic activities of Cu/N-codoped TiO₂ showed the highest activities than other TiO₂ nanoparticles (TiO₂ and N-doped TiO₂). The photodegradation efficiency of Cu/N-codoped TiO₂ on phenanthrene under visible light irradiation was slightly higher (96%) comparing to UV light irradiation (94%). Cu/N-codoped TiO₂ was found to be very efficient and economical for phenanthrene removal, because the smallest amount of Cu/N-codoped TiO₂ exhibited the best removal efficiency on phenanthrene.

Ni/Si-Codoped TiO2 Nanostructure Photoanode for Enhanced Photoelectrochemical Water Splitting

We synthesized Ni/Si-codoped TiO₂ nanostructures for photoelectrochemical (PEC) water splitting, by electrochemical anodization of Ti-1Ni-5Si alloy foils in ethylene glycol/glycerol solutions containing a small amount of water. The effects of annealing temperature on PEC properties of Ni/Si-codoped TiO₂ photoanode were investigated. We found that the Ni/Si-codoped TiO₂ photoanode annealed at 700 °C had an anatase-rutile mixed phase and exhibited the highest photocurrent density of 1.15 mA/cm² at 0 V (vs. Ag/AgCl), corresponding to a photoconversion efficiency of 0.70%, which was superior to Ni-doped and Si-doped TiO₂. This improvement in PEC water splitting could be attributed to the extended light absorption, faster charge transfer, possibly lower charge recombination, and longer lifetime.