Structural, optical, surface chemical, and electrochemical characterization of Aloe vera-assisted ZnO nanostructures for supercapattery applications

Abstract

Material advancement through green synthesis routes is rapidly gaining attention as a sustainable and scalable alternative for nanomaterial fabrication. In this study, zinc oxide nanostructures (Alv-ZnO NSs) were synthesized using Aloe vera gel as a natural reducing and stabilizing agent, eliminating the need for toxic reagents. This work presents the first comprehensive structural, optical, chemical, and electrochemical investigation of Aloe vera-assisted ZnO nanostructures using advanced characterization techniques, such as XRD, XPS, FESEM, and TEM. Rietveld refinement confirmed high crystallinity and phase purity, while thermal analysis showed excellent thermal stability with only ∼2% mass loss up to 750 °C. UV-vis and PL spectroscopy revealed a bandgap of 3.74 ± 0.10 eV and characteristic emissions associated with Zn vacancies and oxygen interstitials, respectively. XPS analysis showed a blue shift in Zn 2p and O 1s peaks, indicating oxygen-rich surfaces and defect sites that contribute to enhanced electrochemical performance. The electrode was characterised by 952.5 F g⁻¹ at 1 A g⁻¹ and 744.66 F g⁻¹ at 1 mV s⁻¹, with 72.9% retention at 10 A g⁻¹, establishing Alv-ZnO NSs as a sustainable, high-performance supercapattery material.