The undoped and cobalt doped TiO2 sols were prepared using sol-gel method. After addition of triethylamine into the respective sol at room temperature, nitrogen and （Co, N） codoped TiO2 sols were obtained. Various thin film electrodes were prepared from the sols using dip-coating approach. These films were characterized by XRD, SEM, XPS, UV-Vis absorption spectroscopy and photocurrent action spectra, and their photoelectrochemical response mechanisms under visible light were also discussed. The results show that the （Co, N） codoped TiO2 electrode exhibits an enhanced incident photon to current efficiency under visible light in comparison with the Co-doped and N doped TiO2 alone. Codoping dose not shift the position of energy band edges of the electrodes where nitrogen exists in the form of NOx. The enhanced photoresponse observed can be attributed to the increase in surface area, light absorbance, interface charge transfer rate of photogenerated carriers and cooperation effect between the doping species.
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