Hematite is a potential candidate for hydrogen production by photoelectrochemical (PEC)
decomposition of water due to its good bad gap and excellent chemical stability. However, its poor
conductivity limits its PEC performance. Titanium has been predicted to be a good choice of dopant for
improving the conductivity. Most of the Ti-doped hematite films are produced by solution based
method. However, such procedure may introduce impurities. RF sputtering is a clean vacuum deposition
technique, which is perfect for the synthesis of metal oxide. In this paper, we report our synthesis of Tidoped
hematite thin films by RF magnetron co-sputtering of iron oxide and titanium targets at various
conditions. Our work shows that the structure and morphology of iron oxide can be modified by
controlling the doping concentration of titanium. Moreover, we confirmed that the PEC performance of
Ti-doped iron oxide film is significantly better than the undoped one.
Ceramic semiconductor photoelectrodes made of the Fe2O3-Nb2O5 solid solutions were synthesized. The spectral and
capacitance-voltage characteristics of the photoelectrodes were determined, and the dynamic polarization with chopped
light was investigated. The anodic photocurrent onset potential, the flat band potential and the shallow and deep donor
density of these materials were determined. The threshold photon energies corresponding to the inter-band optical
transitions near the edge of the fundamental absorption of the semiconductor photoelectrode were calculated. Analysis
of the frequency dispersion of the real and imaginary parts of the complex impedance of photoelectrochemical cell was
carried out. On the basis of this analysis, equivalent circuits describing the structure of the double electrical layer of the
semiconductor - electrolyte interface were proposed and their parameters were calculated. The main limiting steps of the
electrode processes, which determine the electrode polarization and current, are determined.
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