p-Type CaFe2O4 semiconductor nanorods controllably synthesized by molten salt method

Pure phase, regular shape and well crystallized nanorods of p-type semiconductor CaFe 2 O 4 have been fabricated for the first time by a facile molten salt assisted method, as confirmed by XRD , TEM, SEM and HRTEM. UV−vis diffuse reflectance spectra and Mott–Schottky plots show that the band structure of the CaFe 2 O 4 nanorods is narrower than that of the CaFe 2 O 4 nanoparticles synthesized by conventional method. The enhancement of the visible-light absorption is due to narrowness of the band gap in CaFe 2 O 4 nanorods. The appropriate ratio between the molten salt and the CaFe 2 O 4 precursors plays an important role in inhibiting the growth of the crystals along the (201) plane to give the desired nanorod morphology. This work not only demonstrates that highly pure p-type CaFe 2 O 4 semiconductor with tunable band structure and morphology could be obtained using the molten salt strategy, but also affirms that the bandgap of a semiconductor may be tunable by monitoring the growth of a particular crystal plane. Furthermore, the facile eutectic molten salt method developed in this work may be further extended to fabricate some other semiconductor nanomaterials with a diversity of morphologies.