Highly photoactive Ti-doped α-Fe2O3 nanorod arrays photoanode prepared by a hydrothermal method for photoelectrochemical water splitting

Graphical abstract: Ti-doped α-Fe2O3 nanorod arrays were prepared for photoelectrochemical water splitting by a facile hydrothermal method. With the optimal Ti/Fe atomic ratio, the Ti-doped α-Fe2O3 nanorod arrays show a remarkable photocurrent density, which is 2 order of magnitude higher than that of undoped α-Fe2O3 nanorod arrays. - Highlights: • Ti-doped α-Fe2O3 nanorod arrays were prepared by hydrothermal method. • The effect of Ti ions on Ti-doped α-Fe2O3 was studied by electrochemistry techniques. • Ti-doped α-Fe2O3 exhibits a photocurrent density of 0.72 mA/cm2 at 0.23 V vs. Ag/AgCl. - Abstract: In this work, we report the Ti-doped α-Fe2O3 nanorod arrays prepared by a facile approach as well as their implementation as photoanodes for photoelectrochemical water splitting. Impedance measurements show that the Ti dopant serves as electron donor and increases the donor density of Ti-doped α-Fe2O3 nanorod arrays to 2.4 × 1019 cm−3, which is approximately 4 times higher than that of undoped α-Fe2O3 nanorod arrays. Photoelectrochemical impedance spectroscopy shows that photogenerated holes could be transferred from valence band of hematite to electrolyte more efficiently in Ti-doped α-Fe2O3 nanorod arrays. With the optimal Ti/Fe atomic ratio, Ti-doped α-Fe2O3 nanorod arrays exhibit a remarkable photocurrent density of 0.72 mA/cm2 at 0.23 V vs. Ag/AgCl, which is 2 order of magnitude higher than that of undoped α-Fe2O3 nanorod arrays. The enhancive photoelectrochemical activity of Ti-doped α-Fe2O3 nanorod arrays is attributed to the improved donor density and reduced recombination of the electron-hole pairs