ECO-FRIENDLY FABRICATION OF MANGANESE–NICKEL–VANADIUM SULFIDE-BASED COMPOSITES WITH ZNO, TIO₂, AND AG FOR ENHANCED SUPERCAPACITOR PERFORMANCE

Abstract

We report a scalable, environmentally benign hydrothermal approach for synthesizing ternary manganese–nickel–vanadium sulfide (Mn–Ni–V–S) composites decorated with zinc oxide (ZnO), titanium dioxide (TiO₂), and silver nanoparticles (Ag NPs) for high-performance supercapacitor electrodes. The entire fabrication protocol employs water as the primary solvent and avoids hazardous organic precursors, rendering the synthesis green and sustainable. Structural characterization by X-ray diffraction (XRD), Raman spectroscopy, and high-resolution TEM confirms phase-pure sulfide nanostructures with intimate interfacial coupling. The BET surface area reaches 318.4 m² g⁻¹, indicating a highly porous architecture. Electrochemical evaluation in 2 M KOH reveals a specific capacitance of 1872 F g⁻¹ at 1 A g⁻¹, energy density of 58.6 Wh kg⁻¹, and 93.7% capacitance retention over 10,000 cycles. The synergistic contributions from multiple redox-active sulfide phases, Ag-mediated conductivity enhancement, and ZnO/TiO₂ heterojunctions collectively amplify the pseudocapacitive response. This work establishes a green-chemistry pathway toward next-generation energy storage materials.