Numerical analysis of titanium vapor in CVD furnace toward growing titanium oxide nanowires on diatom frustules

Abstract

To address the problem of low energy conversion efficiency in DSSC, a lot of ways have been applied to improve the light scattering and electrons transport abilities of photoanode. However, few have studied fabricating TiO2 nanowires on diatom frustules as photoanode material. To make better experimental design for the successful growth of TiO2 nanowires on diatom frustules with thermal evaporation method, a COMSOL Multiphysics model focused on the gas flow, heat transfer and mass transport based on momentum, energy, mass conservation equations was built to simulate the process of Ti vapor transport in a CVD furnace. The time required for a complete distribution of Ti vapor to reach steady state was estimated, Ti vapor concentration and flux variation with the change in experimental conditions, such as heating temperature, tube pressure and Ar flow rate were studied as well. The numerical simulation results indicated that higher heating temperature and higher tube pressure caused a higher Ti vapor concentration and flux along the tube, while higher Ar flow rate caused a higher Ti vapor flux but a lower concentration along the tube. With this model, growth characteristics of TiO2 nanowires on diatom frustules can be explained numerically.