Supersonic aerosol-deposited TiO₂ photoelectrodes for photoelectrochemical solar water splitting

Photoelectrochemical (PEC) water-splitting is a promising approach for economical and environmentally friendly hydrogen production. We report here the preparation of nanocrystalline TiO₂ films by aerosol deposition (AD) and their performance as photoelectrodes for PEC water splitting. The AD deposited films, 0.5 to 4 μm in thickness, were analyzed to establish the dependence of water splitting performance on film thickness, morphology, and crystallinity. Film thickness and annealing were found to strongly influence the photoelectrochemical water splitting performance. As-deposited TiO₂ films exhibited much higher photoelectrochemical activity than annealed TiO ₂ films. The as-deposited, 3 μm thick TiO₂ films exhibited the highest photocurrent density, 93 μA cm^-2 at -0.2 V vs. Ag/AgCl, under UV illumination (100 mW cm^-2). The same films annealed at 500 °C showed a much lower photocurrent density of 2.9 μA cm^-2 at 0.2 V vs. Ag/AgCl.