Research Article

Solvent-Engineered Synthesis of V₂O₅ for Enhanced Supercapacitor Performance

Abstract

Vanadium pentoxide (V₂O₅) is considered a promising electrode material for supercapacitors due to its rich redox chemistry, high theoretical capacitance, and layered structure conducive to ion intercalation. However, its practical performance is often limited by poor electrical conductivity and structural instability during cycling. In this study, a series of vanadium pentoxide (V₂O₅)-based electrode materials were synthesized via a solvothermal route by varying the ratio of isopropyl alcohol (IPA), glycerol, and deionized (DI) water to investigate their influence on structural, morphological, and electrochemical properties for supercapacitor applications. X-ray diffraction (XRD) confirmed the orthorhombic phase of V₂O₅ in all samples, while UV–Vis spectroscopy showed solvent-driven modulation of optical bandgaps, indicating altered electronic structures. X-ray photoelectron spectroscopy (XPS) revealed mixed-valence vanadium states and oxygen vacancies, particularly in glycerol-rich samples. Surface morphology examined through scanning electron microscopy (SEM) revealed solvent-dependent architectures from compact aggregates in water-only samples to highly porous, flower-like assemblies in mixed solvent systems. Notably, Sample 3, prepared with 40:20:10 mL of IPA, glycerol, and DI water, exhibited a 3D nanosheet-based morphology, confirmed by transmission electron microscopy (TEM), which enhances ion accessibility and shortens diffusion pathways. Energy-dispersive X-ray spectroscopy (EDS) elemental mapping verified the homogeneous distribution of V and O elements across all samples, confirming compositional consistency. Electrochemical studies, including cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS), demonstrated that Sample 3 delivered the highest specific capacitance (~104 F g⁻¹), excellent redox reversibility, and low charge-transfer resistance. These results highlight the critical role of solvent engineering in tuning the morphology and electrochemical performance of V₂O₅-based electrodes, making them promising candidates for high-efficiency supercapacitors.