Flame doping of indium ions into TiO₂ nanorod arrays for enhanced photochemical water oxidation

Indium (In) ions were diffused into a TiO₂ (In-TiO₂) photoelectrode via a facile and efficient flame doping method resulting in improved photo-induced carrier separation. The dopant concentration was systematically investigated, and a volcano-type relationship between the dopant concentration and photoelectrochemical (PEC) performance was observed. The optimum incident photon-to-current efficiency and photocurrent density of In-TiO₂ were 38.6% and 0.70 mA cm^-2 at 1.23 V, respectively, 2.1 and 11.2 times the values of pristine TiO₂, respectively. In doping resulted in improved charge separation and lower surface adsorption energies for reactant molecules, as evidenced by experimental and computational methods.