Electrodeposited nanostructured α-Fe2O3 thin films for solar water splitting: Influence of Pt doping on photoelectrochemical performance

Electrochemically deposited α-Fe2O3 thin films, whose composition was tuned by Pt doping, were investigated as photoanode for photoelectrochemical water splitting. Morphological and structural characteristics of the nanostructured α-Fe2O3 thin films were studied by scanning electron microscopy and X-ray diffraction techniques. The films were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy to determine the effect of Pt doping on the α-Fe2O3 structure. The photoelectrochemical performance of the films was examined by linear sweep voltammetry and electrochemical impedance spectroscopy. Results of these studies showed that Pt doping increased the density of small-sized nanoparticles in α-Fe2O3 thin films. The Pt doped films exhibited higher photoelectrochemical activity by a factor of 1.4 over un-doped α-Fe2O3 films. The highest photocurrent density of 0.56 mA cm−2 was registered for 3% pt doped film at 0.4 V versus Ag/AgCl in 1 M NaOH electrolyte and under standard illumination conditions (AM 1.5 G, 100 mW cm−2). This high photoactivity can be attributed to the high active surface area and increased donor density caused by Pt doping in the film. Electrochemical impedance analysis also revealed significantly low charge transfer resistance of Pt doped films, indicating its superior electrocatalytic activity for water splitting reaction compared to un-doped α-Fe2O3 thin films.