Construction and application of α-Fe2O3 nanocubes dominated by the composite interaction between polyvinyl chloride and potassium ferrocyanide

Abstract

The present work provides a novel route for the preparation of hematite (α-Fe₂O₃) nanocubes by a facile, one-step procedure through a noncovalent composite interaction between polyvinyl chloride (PVC, a polymer) and potassium ferrocyanide (PF, a coordination compound) with an initial molar ratio of 20 : 1. Field-emission scanning electron microscopy analysis reveals the formation of well-ordered α-Fe₂O₃ nanocube granules featuring a uniform and smooth outer surface. Control experiments show that the composite ratios of PVC to PF played a crucial role in generating the nanocubic structure. Temperature-dependent sintering experiments proved that the α-Fe₂O₃ nanocubes were derived from a structural transformation from nanoplates emerging at lower temperatures, suggesting a condition optimization process of the 2D plate structure to the 3D cubic structure. The one-step synthesis of the nanoplates at lower temperatures is considered to be related to the composite interaction between PVC and PF. A series of independent experiments including Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and conductivity were performed to explain the presence of the composite interaction. Interestingly, we found that the composite interaction has improved considerably the physical properties of the polymer (e.g., crystallization degree and glass transition temperature) and the coordination compound (e.g., conductivity and microwave absorption ability). Finally, our data indicate that the as-prepared α-Fe₂O₃ nanocubes exhibited a higher lithium storage capacity and better cycling performance than the α-Fe₂O₃ nanoparticles with irregular shapes. We believe that the present results open up many opportunities in nanostructural materials of metal oxides associated with the composite interaction between a polymer and a coordination compound.