Spectroelectrochemical analysis of conduction band edge shift in nanoporous TiO2 electrodes

• The shift of Vfb of TiO2 electrode is obviously dependent on the surface reaction.
• The properties of TiO2 thin-film obviously impact on the shift of Vfb.
• The mechanism of Vfb shift in substitutional dopant into TiO2 lattice is proposed.
• N and Mg2+ incorporation into titania lattice result in the negative shift of Vfb.

In this work, conduction band edge (Vfb) shift in the nanostructure TiO2 electrodes was investigated in detail using photoelectrochemical methods. The density of conduction band at a given applied potential was affected by the electrochemical reaction on the nano-TiO2 surface and spectroelectrochemistry techniques could determinate Vfb from the measured absorbance as a function of applied potential for the TiO2 electrodes. It is indicated that the increased thickness of TiO2 electrodes led to the positive shift of conduction band edge (Vfb), which resulted in the increased reaction rate of electrochemical reaction in nanostructure TiO2 electrode. The N and Mg2+ incorporation into the TiO2 lattice resulted in the negative conduction band edge, and an analytical dependence of the photoelectrochemical methods on the TiO2 surface performance found that the negative shift of Vfb could be attributed to the substitutional dopant into TiO2 lattice to decrease the electrochemical surface reaction in the photoelectrodes.