Observation of synergistic effects in multiphase tungsten oxide (WO3) nanocomposite and its role in enhanced supercapacitive and photoluminescence properties

Abstract

Herein we report the synthesis of metal (W) and multiphase metal oxide (orthorhombic, tetragonal, and hexagonal-phase of WO3) nanocomposites through a simple hydrothermal process and the electrochemical performance of this composite displays enormous specific capacitance (CS) of 1885 F/g in 1 M H2SO4. The distinct phases of the metal tungsten and WO3 nanoplates have been identified by XRD, FTIR and Raman spectra. This study also demonstrates how the different intercalated ionic radius significantly alters the electrochemical performance with the W–O bond length and displays moderately higher CS in 1 M H2SO4 (1885 F/g) compared to 2 M KOH (821 F/g) electrolytes at 1 mV/s scan rate. The proton (H+ and K+) insertion dynamics is also explored by galvanostatic charge-discharge (GCD), scan rate-dependent electrochemical analysis and electrochemical impedance spectroscopy (EIS). The enhanced W5+ to W6+ intercalation efficiency of the individual phase of WO3 has been demonstrated by three imperfectly resolved arcs with slopes line in acidic solution of EIS spectrum, whereas a single arc with slope in the KOH solution indicates less reaction kinetics in base solution. Moreover, multiphase WO3 nanoplates show outstanding 96.6% capacitance retention in 1 M H2SO4 compared to 2 M KOH (86.2%) solution after 900 cycles at a 10 A/g current density. Based on W-WO3 nanoparticle's improved three-electrode activity, we have constructed a solid-state asymmetric supercapacitor (ASC), and it exhibits energy densities of 76.3 Wh/kg and 86.8 Wh/kg at power densities of 1125 W/kg in KOH and H2SO4 soaked devices, respectively. Linear dependence of the excitation-dependent luminance spectra (250 nm–300 nm) and clean PL spectra at the lowest excitation (1.5 W) make these multiphase WO3 nanoplates a promising candidate as UV-B detector materials. So the multifunctionality of the WO3 nanostructures makes it a potential candidate as a future-generation integrated device materials.