Morphology-Controlled synthesis of hematite nanocrystals and their optical, magnetic and electrochemical performance

A series of α-Fe₂O₃ nanocrystals (NCs) with fascinating morphologies, such as hollow nanoolives, nanotubes, nanospindles, and nanoplates, were prepared through a simple template-free hydrothermal synthesis process. The results showed that the morphologies could be easily controlled by SO₄²⁻ and H₂PO₄⁻. Physical property analysis showed that the α-Fe₂O₃ NCs exhibited shape-and size-dependent ferromagnetic and optical behaviors. The absorption band peak of the α-Fe₂O₃ NCs could be tuned from 320 to 610 nm. Furthermore, when applied as electrode material for supercapacitor, the hollow olive-structure exhibited the highest capacitance (285.9 F·g⁻¹) and an excellent long-term cycling stability (93% after 3000 cycles), indicating that it could serve as a candidate electrode material for a supercapacitor.