Nickel sulfide sensitized TiO_2 nanotubes system as photo-anode: Will this system active under visible light and why

摘要

This work is dedicated to enhance the photo catalytic activity of the modified 2 nanotube under visible light exposure. The narrow band gap of semiconductor such as NiS can be incorporated onto TiO_2 nanotube (NiS/TiO_2-NT) to obtain a composite which may active under visible light. The TiO_2 nanotube was self-prepared by electro-oxidation of titanium plate in electrolyte containing ethylene glycol, NH4F, and water. Meanwhile, the incorporation of NiS onto TiO_2 film was prepared by successive ionic layer absorption and reaction (SILAR) method, in which nickel(II) ion and sulfide ion were used as the precursor of NiS, to obtain the NiS/TiO_2-NT film system. The obtained NiS/TiO_2-NT films were characterized by UVDRS, FTIR, SEM, XRD, and photo-electro-chemical work station. The resultsindicated that the peak of absorption spectra of NiS/TiO_2-NT fall within thevisible light region, which the final band gap was 2.85 eV; IR and XRD spectra were also revealed the characteristic peak of NiS/TiO_2-NT system. Photo-electrochemical investigation revealed that the evolution of photocurrent under visible light (100 W wolfram lamp), as much as 0.26 mA/cm~2 typically can be easily observed.