One-step template-free synthesis of hollow core–shell α-Fe2O3 microspheres with improved lithium storage and gas-sensing properties

Abstract

Hollow core–shell α-Fe₂O₃ microspheres were easily prepared by a one pot hydrothermal method without employing any templates/substrates or surfactants. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and nitrogen adsorption–desorption isotherms. Results showed that the shell was constructed by aggregated α-Fe₂O₃ nanoparticles, while the core presented a novel porous structure. The morphology of the hollow core–shell α-Fe₂O₃ microspheres can be controlled by optimizing the experimental conditions. A possible formation mechanism was also proposed. As anodes in lithium ion cells, the hollow core–shell α-Fe₂O₃ microspheres show a high initial discharge capacity of 1465 mA h g⁻¹ and still a rather high capacity of 728 mA h g⁻¹ after 60 cycles. When applied as gas sensors, the hollow core–shell α-Fe₂O₃ microspheres exhibited high gas sensitivity toward NO₂ gas. The intrinsic hollow core–shell nature as well as high porosity of the core contributes greatly to the improvement of their performance as anode materials for lithium ion batteries and the superior sensitivities to NO₂ gas.