Eco-Friendly Synthesis of Zinc Cobaltite Using Piper nigrum Extract: Structural, Morphological and Electrochemical Properties for Energy Storage

Author : N. Varalakshmi, A. Lakshmi Narayana, O. M. Hussain

Abstract : Green synthesis strategies provide sustainable pathways for advanced energy materials by minimizing hazardous reagents and energy-intensive processes. In this work, zinc cobaltite (ZnCo₂O₄, ZCO) nanoparticles were synthesized using Piper nigrum (black pepper) extract as a natural reducing and stabilizing agent. XRD analysis confirmed the polycrystalline spinel phase, with greater crystallite sizes in ZCO @ pure compared to ZCO@300 and ZCO@500.Upon incorporation of black pepper extract. Electrochemical behavior was systematically evaluated using the Dunn plot method, where log(i) versus log(v) analysis provides mechanistic insight into charge storage. The slope values revealed distinct regimes: ZCO@500 exhibited a slope of ≈0.50, indicating diffusion-controlled dominance; ZCO@300 showed ≈0.58, consistent with a mixed mechanism leaning toward diffusion; and ZCO@300 with extract displayed ≈0.33, reflecting strong diffusion control. Among all samples, ZCO@500 demonstrated the highest specific capacitance, underscoring its suitability for high-performance supercapacitors. These findings highlight the dual role of Piper nigrum extract in tailoring crystallite size and optimizing electrochemical kinetics, establishing a green and scalable synthesis route for next generation energy storage materials.

Keywords : Zinc Cobaltite, piper nigrum extract, green synthesis, electrochemical properties, supercapacitors, structural characterization.

Conference Name : International Conference on Nanotechnology-Enhanced Energy Storage and Conversion (ICNEESC-26)

Conference Place : Hyderabad, India

Conference Date : 28th Feb 2026