Surface Tuning for Promoted Charge Transfer in Hematite Nanorod Arrays as Water-Splitting Photoanodes

Hematite (alpha-Fe2O3) nanorod films with their surface tuned by W6+ doping have been investigated as oxygen-evolving photoanodes in photoelectrochemical cells. X-ray diffraction, field emission scanning electron microscopy, UV-visible absorption spectroscopy, and photoelectrochemical (PEC) measurements have been performed on the undoped and W6+-doped alpha-Fe2O3 nanorod films. W6+ doping is found to primarily affect the photoluminescence properties of alpha-Fe2O3 nanorod films. Comparisons are drawn between undoped and W6+-doped alpha-Fe2O3 nanorod films, WO3 films, and alpha-Fe2O3-modified WO3 composite electrodes. A close correlation between dopant concentration, photoluminescence intensity, and anodic photocurrent was observed. It is suggested that W6+ surface doping promotes charge transfer in alpha-Fe2O3 nanorods, giving rise to the enhanced PEC performance. These results suggest surface tuning via ion doping should represent a viable strategy to further improve the efficiency of alpha-Fe2O3 photoanodes.