Modelling of photo-electrocatalytic behaviour of TiO2 nanotubes under solar light irradiation

A mathematical model of the photo-electrochemical processes occurring during irradiation with solar light has been implemented, to evaluate the optimal geometry of TiO2 nanotubular structures for the different applications. The model accounts for generation and recombination of charge carriers, as well as for transport phenomena in solid phase. Electrochemical reactions at the surface and chemical processes in liquid phase are also modelled. The solar irradiation has been discretised in the UV and visible range, and adsorption coefficients as a function of the wavelength have been used. The model has been solved for oxidation of water, as well as for oxidation of organic compounds with different reactivity. The effect of such variables as light intensity, electric potential and reactivity of the organic compounds on space distribution of charge carriers in solid phase, oxygenated radicals and organic compounds in liquid phase, have been determined. The model provides a versatile tool to assess the performances of nanotubular electrodes at microscale and makes possible the optimal design of the nanostructure.