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 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 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.

Surface-Sulfurized Zn-MOF Grown on Ni-Foam with Various Sulfurizing Agents for Aqueous Hybrid Supercapacitor Device Fabrication

“…If the b value lies between 0.5 and 1, then it corresponds to the combined contribution of EDLC and faradaic redox charge storage. 44 In Figure 7a,c, ZnSCO-TU@NiF and ZnSCO-S@NiF provide broad potential regions for faradaic redox contribution. These types of behaviors correspond to large diffusion resistance due to buried pores in the materials.…”

“…If the b value is 0.5, then it is fully faradaic for redox charge storage. If the b value lies between 0.5 and 1, then it corresponds to the combined contribution of EDLC and faradaic redox charge storage . In Figure a,c, ZnSCO-TU@NiF and ZnSCO-S@NiF provide broad potential regions for faradaic redox contribution.…”