Ti-doped hematite nanostructures for solar water splitting with high efficiency

Ti-doped hematite nanostructures have been synthesized for efficient solar water splitting by adding TiCN as the Ti precursor in a hydrothermal method. Ti-doped hematite nanostructures show an urchin-like morphology with nano feature size, which increases the effective surface area compared to undoped nanostructures. A remarkable plateau photocurrent density value of 3.76 mA/cm(2) has been observed for Ti-doped nanostructures under standard illumination conditions in 1M NaOH electrolyte, which is 2.5 times higher than that for undoped nanostructures (1.48 mA/cm(2)). The photocurrent at 1.23V vs. RHE (1.91 mA/cm(2)) is also enhanced to be over 2 times higher than that for undoped nanostructures (0.87 mA/cm(2)). X-ray photoelectron spectroscopy and x-ray absorption spectroscopy have been used to investigate the electronic structure of Ti-doped hematite, which suggest the increased donor density of hematite by Ti doping. The remarkable plateau current density in Ti-doped hematite nanostructures can be attributed to both the favorable urchin-like morphology and the Ti doping. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759278]