Core–Shell (W@WO₃) Nanostructure to Improve Electrochemical Performance

Abstract

Two different approaches were developed to fabricate core–shell tungsten and tungsten oxide (W@WO3) nanostructures in combination with a hydrogen reduction technique. One is a combination of aerosol and pyrolysis approaches, which produce spherical tungsten oxide nanoparticles with a hexagonal crystal structure. The other is a combination of templating and impregnating approaches, which lead to tungsten oxide with a monoclinic crystalline structure. Subsequent hydrogen reduction lead to the formation of core–shell W@WO3 nanostructures with two different tungsten metallic phases. Structural and morphological characterizations were performed using X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The electrochemical performance of W@WO3 electrodes synthesized by two different approaches was studied using cyclic voltammetry, impedance spectroscopy, and galvanostatic charge–discharge methods. The capacity of core–shell W@WO3 nanostructures can reach 148 F g–1 compared with 21 F g–1 at 0.43 A g–1 for the WO3 sample, which is also higher than the reported literature value. It is shown that the W@WO3 nanostructures have significantly better electrochemical performance than WO3 alone.