Maghemite (hematite) core (shell) nanorodsviathermolysis of a molecular solid of Fe-complex

Abstract

An Fe-metal complex with 2′-hydroxy chalcone (2′-HC) ligands [Fe(III) (2′-hydroxy chalcone)₃] is synthesized by a chemical route and is subjected to different thermal treatments. Upon thermolysis in air at 450 °C for 3 h the complex yields maghemite (γ-Fe₂O₃) nanorods with a thin hematite (α-Fe₂O₃) shell. X-Ray diffraction (XRD), Mössbauer spectroscopy, diffuse reflectance spectroscopy (UV-DRS), high resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometry (VSM) are used to characterize the samples. The stability of the ligand and the Fe-complex is further examined by using thermogravimmetric/differential thermal analysis (TGA/DTA). We suggest a residual ligand controlled mechanism for the formation of an anisotropic nanostructure in a crumbling molecular solid undergoing ligand decomposition. Since the band gap of iron oxide is in the visible range, we explored the use of our core shell nano-rod sample for photocatalytic activity for H₂ generation by H₂S splitting under solar light. We observed high photocatalytic activity for hydrogen generation (75 ml h⁻¹).