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 300C 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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