Microwave-assisted green fabrication of nickel foam–reduced graphene oxide–nickel sulfide nanocomposite: Structural, spectroscopic, and electrochemical performance evaluation for supercapacitor applications

Prabaharan  Panchanathan; Maadathi  Sivakumar; Gunasekaran  Marudhai; Brindha Ganesan; Sivasankari Gnanam; Boobalan  Sivalingam; Devi  Selvaraj

doi:10.20450/mjcce.2026.3562

Authors

Prabaharan Panchanathan Department of Chemistry, Government Polytechnic College Tiruchirappalli– 620 022, India. and Department of Chemistry, Cauvery College for Women (A), Tiruchirappalli – 620 018, India, Affiliated to Bharathidasan University https://orcid.org/0009-0007-9562-4703
Maadathi Sivakumar Department of Chemistry, Cauvery College for Women (A), Tiruchirappalli –620 018, India. Affiliated to Bharathidasan University
Gunasekaran Marudhai Department of Chemistry, J J College of Engineering and Technology, Tiruchirapalli - 620 009
Brindha Ganesan Department of chemistry, V.S.B. Engineering College Autonomous Karur - 639111. India
Sivasankari Gnanam Department of Chemistry, Cauvery College for Women (A), Tiruchirappalli – 620 018, India, Affiliated to Bharathidasan University https://orcid.org/0000-0001-9745-8322
Boobalan Sivalingam Department of Chemistry, Indra Ganesan College of Engineering, Manikandam, Tiruchirappalli – 620012. India
Devi Selvaraj Department of Chemistry, Cauvery College for Women (A), Tiruchirappalli – 620 018, India, Affiliated to Bharathidasan University https://orcid.org/0000-0001-8811-5870

DOI:

https://doi.org/10.20450/mjcce.2026.3562

Keywords:

Green synthesis, Nickel sulfide nanoparticles, Reduced graphene oxide nanocomposite, Coccinia grandis leaf extract, Supercapacitor electrode materials

Abstract

A microwave-assisted green synthesis route was employed to fabricate a nickel foam–reduced graphene oxide–nickel(II) sulfide (Ni foam–rGO–NiS) nanocomposite using Coccinia grandis leaf extract as the bio-reducing and stabilizing agent for supercapacitor applications. The Ultraviolet - Visible (UV) spectrum revealed an absorption peak of 239 nm (rGO) and 313 nm (NiS), confirming the formation of a composite that facilitates efficient electron transfer between the two components, potentially reducing the band gap energy. Fourier Transform Infrared spectra (FTIR) confirmed successful loading of NiS nanoparticles onto rGO, with associated phytochemical functional groups acting as reducing, capping, and stabilizing agents. X-ray Diffraction (XRD) patterns validated formation of hexagonal NiS and reduction in the sheet structure of rGO, thereby elucidating the nature of the nanocomposite. The average crystallite size, estimated using the Debye–Scherrer equation, was approximately 2–5 nm (NiS) and approximately 30.4 nm (rGO). The surface morphology of the nanocomposite displayed an exfoliated wrinkled sheet structure, with NiS particles uniformly dispersed throughout. Elemental analysis verified that the material had achieved the expected purity levels, with no detectable impurities, while the Dynamic Light Scattering (DLS) indicated a particle size of approximately 100 nm in solution. The Ni foam–rGO–NiS electrode demonstrated significantly enhanced electrochemical performance. Cyclic voltammetry conducted at the same scan rate revealed intense redox peaks, thus confirming pseudocapacitive behavior. Electrochemical impedance spectroscopy (EIS) indicated low charge-transfer resistance with high electrochemical activity. This electrode achieved a high specific capacitance of approximately 633.3 F g^–¹ at 1 A g^–¹ and approximately 422.2 F g^–¹ at 5 A g^–¹, as well as exhibiting good rate capability and cycling stability, with 80–85% capacitance retention over 3000 cycles. The synergistic combination of highly conductive rGO, redox-active NiS, and porous Ni foam enhanced charge storage and transportation. The prepared green-synthesized, reduced graphene oxide–nickel(II) sulfide nanocomposite is proposed as a promising electrode nanomaterial for supercapacitor applications.

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