Enhancement of photocatalytic activity of P25 TiO2 by vanadium-ion implantation under visible light irradiation.

An ion-implantation method was used to prepare V-ion-implanted P25 TiO2 photocatalysts. Their photocatalytic activity for the degradation of formic acid under visible light irradiation (lambda>450 nm) was investigated. Upon implantation of V ions into the lattice of P25 TiO2, the photoactivity was remarkably enhanced. HRTEM images showed that the implanted V ions existed in the form of VO2(T) in the lattice of P25 TiO2. The intensity of photoluminescence (PL) spectra of V-ion-implanted P25 TiO2 decreased with the increase of the amount of implanted V ions, indicating the decrease of electron-hole pair recombination. It was also observed that the lower the PL intensity of V-ion-implanted P25 TiO2, the higher the photoactivity.