Hierarchical Nanostructured TiO2 Films Prepared by Reactive Pulsed Laser Deposition for Photoelectrochemical Water Splitting

Hierarchical tree-like TiO2 nanostructures prepared by PL D are proposed as photoanodes for photoelectrochemical water plitting. The structural/morphological properties of the TiO2 nanostructures have been tuned via a fine control of the growth parameters (e.g., background gas pressure), of the mass of catalyst, and of the annealing treatments. A correlation between structural/morphological properties and photoelectrochemical behaviour was found. The best performances were associated with the sample prepared at 5Pa of oxygen, possibly because optimize d values of density/surface area, crystallinity and electron transport are achieved. The effect of the variation in the mass of deposited material, which leads to an increased thickness of the catalytic layers, clearly shows the existence of an optimal thickness value that can guarantee improved electron transfer. Thermal annealing at 650°C resulted in an increased degree of crystallinity which positive affe cts the photoelectrochemical response.