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

Uniform rectangular α-Fe 2 O 3 nanorods (R-Fe 2 O 3 ) and irregular α-Fe 2 O 3 nanorods (D-Fe 2 O 3 ) 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 α-Fe 2 O 3 , and XRD patterns show that D-Fe 2 O 3 has two extra (012) and (104) planes of hematite in addition to the identical peaks to R-Fe 2 O 3 . The carrier density of the D-Fe 2 O 3 sample is four times larger than that of R-Fe 2 O 3 . Finally, the D-Fe 2 O 3 photoelectrode exhibited a better photoelectrochemical (PEC) performance under visible illumination than that of R-Fe 2 O 3 , 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-Fe 2 O 3 is nearly three times larger than that of R-Fe 2 O 3 . Hence, the improved PEC performance of D-Fe 2 O 3 can be ascribed to higher carrier density resulting from the amount of oxygen vacancies and more activated exposed surface facets.