Evaluation of the correlations between temperature, humidity, incident UV light and the photocatalytic activity of TiO2films using a rationale approach

The effect of temperature, humidity and incident UV light on the photocatalytic activity of two TiO2filmswith different microstructures (dense and mesoporous) was explored in terms of stearic acid degradation.Previous works reported in the literature suggest that the activity of TiO2films does not only depend onsingle factors but also on interactions between them. Hence, the design of experiments (DoE) approachwas used in this work to plan the experiments in a systematic way, simultaneously considering severalvariables. This approach provided an efficient working strategy to explore both individual and interactioneffects on the photocatalytic activity of the films. The statistical evidence found here revealed that singlefactors temperature and mesoporous microstructure have the strongest positive effect on the efficiencyof the films. In the case of temperature, this was explained by easier degradation and/or desorption ofreaction intermediates. On the other hand, the positive effect of the mesoporous microstructure wascorrelated with its large surface area. An interaction factor between temperature and incident UV lightalso affects the activity of the films. Results suggest that this phenomenon depends of the degree of filmhydration before the deposition of SA.