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

This paper details an approach for the synthesis of stable electroactive Au–V 2 O 5 –MnO 2 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. MnO 2 and Au formed a profitable hierarchical network morphology in the interstitial sites of V 2 O 5, and this kind of synergetic architecture exhibits an elevated specific capacitance (388 F g –1 at 1 A g –1 ) compared to commercial V 2 O 5 (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 V 2 O 5 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 MnO 2 and non-Ohmic electrical conduction, characterized by the onset voltage V 0 (dc) and onset frequency f 0 (ac). These two onset parameters followed power-law behavior with Ohmic conductance with two onset exponents ( x V and x f ). Such electrical transport properties were explained using intrachain hopping conduction of charge carriers within the layers of pristine V 2 O 5 and hopping of charge carriers between the layers of V 2 O 5 in the Au–V 2 O 5 –MnO 2 nanocomposite and supported the interstitial incorporation of the compounds.