Increased Active Sites on Irregular Morphological α-Fe2O3 Nanorods for Enhanced Photoelectrochemical Performance

Uniform rectangular alpha-Fe2O3 nanorods (R-Fe2O3) and irregular alpha-Fe2O3 nanorods (D-Fe2O3) with a random size vertically aligned on fluorine-doped tin oxide were prepared with a facile one-step hydrothermal procedure. X-ray diffraction (XRD) measurements and Raman spectra confirm that the obtained samples are alpha-Fe2O3, and XRD patterns show that D-Fe2O3 has two extra (012) and (104) planes of hematite in addition to the identical peaks to R-Fe2O3. The carrier density of the D-Fe2O3 sample is four times larger than that of R-Fe2O3. Finally, the D-Fe2O3 photoelectrode exhibited a better photoelectrochemical (PEC) performance under visible illumination than that of R-Fe2O3, achieving the photocurrent density of 0.15 mA cm(-2) at 1.23 V versus reversible hydrogen electrode. In addition, incident photo-to-current conversion efficiency of D-Fe2O3 is nearly three times larger than that of R-Fe2O3. Hence, the improved PEC performance of D-Fe2O3 can be ascribed to higher carrier density resulting from the amount of oxygen vacancies and more activated exposed surface facets.