Hematite nanorods with tunable porous structure: Facile hydrothermal-calcination route synthesis, optical and photocatalytic properties

One-dimensional hematite (α-Fe2O3) nanostructures have attracted much concern due to their distinguished utilizations in nanomagnetism, photoanodes, and gas sensors. In order to extend the applications of hematite, a facile fast nontoxic method to synthesize 1D hematite nanostructures is highly required. In this contribution, α-Fe2O3 nanorods with tunable porous structure and optical absorbance properties were successfully synthesized via a facile hydrothermal-calcination route. Uniform high aspect ratio α-FeOOH nanorods with a length of ca. 600 nm, diameter of ca. 30 nm, and aspect ratio of ca. 20 were synthesized via a mild hydrothermal treatment (150 °C, 6.0 h) of the co-precipitation of FeCl3 and NaOH solutions followed by a subsequent calcination (400 or 700 °C in the presence of NaCl). The presence of the CTAB with a mass ratio of 5.0% favored the preferential growth of the α-FeOOH nanorods with larger aspect ratio, while the thermal decomposition of α-FeOOH at 400 or 700 °C in the presence of NaCl led to the high aspect ratio (ca. 15) porous or low aspect ratio (ca. 5) nonporous α-Fe2O3 nanorods, respectively. The UV–vis spectra showed that the optical absorbance properties of the calcined porous/nonporous α-Fe2O3 nanorods were well tuned, and the photocatalytic evaluation revealed that the nonporous α-Fe2O3 nanorods exhibited higher degradation efficiency for RhB than porous α-Fe2O3 nanorods. The as-obtained α-Fe2O3 nanorods with tunable porous structure as well as the tunable optical and photocatalytic properties suggested their great potential applications in the near future.