Redox-Guided Synthesis of Au–V2O5–MnO2 Nanoflower Composites with Enhanced Electrical Conductance for Supercapacitor Applications

Abstract

This paper details an approach for the synthesis of stable electroactive Au–V2O5–MnO2 nanoflower composites using a simple redox-mediated methodology under modified hydrothermal (MHT) conditions. The nanocomposite was characterized by various techniques like X-ray diffraction, scanning electron microscopy, high-resolution transmisson electron microscopy, and X-ray photoelectron spectroscopy. MnO2 and Au formed a profitable hierarchical network morphology in the interstitial sites of V2O5, and this kind of synergetic architecture exhibits an elevated specific capacitance (388 F g–1 at 1 A g–1) compared to commercial V2O5 (85 F g–1 at 1 A g–1) in a neutral electrolyte. The as-synthesized nanocomposite contributed more to energy storage with superior energy density (49 Wh kg–1 at 1 A g–1 current density) and power density (4 kW kg–1 at 10 A g–1 current density) and demonstrated improved stability compared to commercial V2O5 of up to 2000 continuous charge/discharge cycles in a two-electrode system. Temperature- and field-dependent [both direct-current (dc) and alternating-current (ac)] studies exhibited enhanced conductance due to the incorporation of Au and MnO2 and non-Ohmic electrical conduction, characterized by the onset voltage V0 (dc) and onset frequency f0 (ac). These two onset parameters followed power-law behavior with Ohmic conductance with two onset exponents (xV and xf). Such electrical transport properties were explained using intrachain hopping conduction of charge carriers within the layers of pristine V2O5 and hopping of charge carriers between the layers of V2O5 in the Au–V2O5–MnO2 nanocomposite and supported the interstitial incorporation of the compounds.