Aloe Vera-Grown NiO Nanopyramids Store Charge at High Rates

Researchers have synthesized nickel oxide (NiO) nanopyramids using Aloe vera as a green synthesis aid and report that the defect-rich material delivers high specific capacitances as a supercapacitor electrode. According to the study published in Discover Materials, the electrode achieved 674 F g−1 at a current density of 0.5 A g−1, retaining 468 F g−1 at 4 A g−1 and 358 F g−1 at 10 A g−1, which the authors cite as evidence of strong rate capability.

The work centered on correlating the material’s electronic structure, local coordination environment, and defect characteristics with its charge-storage behavior.

Synchrotron X-ray absorption spectroscopy provided a detailed view of the hybridization between Ni-3d and O-2p orbitals, along with the nickel oxidation state and the local coordination environment around the metal centers.

Optical measurements added a further layer of characterization. UV-Vis analysis indicated a bandgap wider than that of bulk NiO, while photoluminescence spectra showed defect-related emissions, consistent with the presence of structural imperfections introduced during the plant-assisted synthesis.

X-ray photoelectron spectroscopy supported this picture, revealing mixed Ni2+/Ni3+ oxidation states with significant contributions from oxygen vacancies.

Electrochemical testing showed that the charge storage was diffusion-controlled pseudocapacitance. The authors note that the combination of defect-engineered electronic structure and this pseudocapacitive behavior underpins the electrode’s performance across a wide range of current densities.

The team positions the study as filling a gap in the literature on Aloe vera-derived NiO by integrating UV-Vis and photoluminescence data, synchrotron-based X-ray absorption spectroscopy, and XPS analysis with electrochemical evaluation in a single correlated framework. Prior reports on plant-derived NiO electrodes had not, in the authors’ view, combined this full set of structural and spectroscopic probes with charge-storage measurements.

The reported capacitance values decline as current density rises, from 674 F g−1 at 0.5 A g−1 to 358 F g−1 at 10 A g−1, a typical trade-off between stored charge and charging rate. The authors conclude that Aloe vera-derived NiO, with its defect-engineered electronic structure, is a sustainable, high-performance candidate electrode material for next-generation hybrid supercapacitors. As with any early-access, peer-reviewed accepted article, the published version remains subject to final editorial edits.

Subject of Research: Green-synthesized defect-rich NiO nanopyramids characterized by synchrotron XRD, XAS and XPS for supercapacitor electrodes

Article Title: Electronic structure, local coordination, and defect insights of aloe vera-derived NiO for supercapacitor applications

Article References: Bhatt, M., Gautam, K., & Sinha, A. K. (2026). Electronic structure, local coordination, and defect insights of aloe vera-derived NiO for supercapacitor applications. Discover Materials. https://doi.org/10.1007/s43939-026-01046-y

Image Credits: AI Generated

DOI: 10.1007/s43939-026-01046-y

Keywords: NiO, Aloe vera, green synthesis, supercapacitor, pseudocapacitance, oxygen vacancies, synchrotron XRD, X-ray absorption spectroscopy, XPS, bandgap, nanopyramids, energy storage