Nano gold coated hierarchically porous zinc titanium oxide sol-gel based thin film: fabrication and photoelectrochemical activity

In this work, for the first time homogeneously distributed near periodic macroporous (HDPM) with nested mesoporous (hierarchically porous) semicrystalline zinc titanium oxide (ZTO) thin film on pure silica glass and fluorine doped tin oxide coated glass substrates was deposited by sol-gel dip coating technique from an optimized precursor solution of zinc nitrate hexahydrate and titanium isopropoxide with acetylacetone in low boiling solvents. The HDPM film formation was carried out by simple breath figure method where the pore formation occurred from the generated water droplets via molecular condensation onto the as-deposited cold solution film surface owing to solvent evaporation. Zinc to titanium ratio in precursor solution, room relative humidity and other critical parameters were tailored towards optimization of the periodic macropores formation. Gold nanoparticles (NPs) were further deposited onto the ZTO thin films by solution technique. Crystallinity, surface morphology and microstructure of the thin films were critically analyzed by X-ray diffraction, atomic force, scanning, and transmission electron microscopic studies. The photoelectrochemical (PEC) performance of the films was examined under visible light irradiation. A significant improvement in PEC activity was observed in nano Au coated hierarchically porous thin film. This facile fabrication process could be applied in different mixed metal oxide thin films for improving the PEC activity of the materials.