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Hydrogen doped TiO2 photo-anodes for photoelettrochemical water splitting

Hydrogen-doped anatase titanium dioxide (H:TiO2) thin films were synthesized by a mild annealing in hydrogen atmosphere of amorphous TiO2 thin film deposited on ITO by RF-magnetron sputtering. Two kinds of TiO2 electrodes (amorphous and anatase) were tested for the H-doping in different annealing conditions. H:TiO2 samples were obtained only when heat treatment was carried out on amorphous TiO2 at 300°C in 1.0 bar of H2 pressure for 10 minutes. XPS experiments revealed that H atoms are linked to O in the film matrix, leading to a passivation of dangling-bonds. Band gap estrapolation from UV-vis spectroscopy measurements revealed a slight gap narrowing, in agreement with density functional theory DFT calculation. The catalytic activity resulted enhanced in H:TiO2, which exhibited an elevated current density of 0.99 mA/cm2 at 1.23 V vs. NHE in oxygen evolution reaction. Such an elevated activity has been accounted to the effect of dangling bond passivation performed by highly reactive H atoms, which reduce the density of carrier recombination centers.

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