Aloe vera-assisted synthesis of MnCo2O4 as a battery-type material for hybrid supercapacitor applications

Abstract

Material advancement in sustainable energy storage is increasingly driven by green chemistry approaches. In this context, we have investigated an Aloe vera-mediated synthesis route for MnCo₂O₄ nanostructures as a battery-type electrode material for hybrid supercapacitor applications. The material was synthesized via an eco-conscious, biogenic route using Aloe vera gel as a natural reducing and stabilizing agent. High-resolution synchrotron XRD and TEM analyses confirmed the formation of single-phase spinel nanocrystals with an average size of ∼12.7 nm, while FESEM revealed aggregated mesoporous clusters indicative of secondary particle formation. BET analysis demonstrated a moderate specific surface area of 43.27 m² g⁻¹ and a dominant pore size around 10 nm, supporting rapid ion transport and efficient electrolyte access. XPS spectra revealed the coexistence of Mn³⁺/Mn⁴⁺ and Co²⁺/Co³⁺ oxidation states, along with abundant oxygen vacancies and/or oxygen interstitials, collectively contributing to enhanced redox kinetics and charge storage capability. The material exhibited excellent electrochemical performance, delivering a high specific capacitance of 680 F g⁻¹ at 1 A g⁻¹ and retaining 282.7 F g⁻¹ even at 80 A g⁻¹ and 365.7 F g⁻¹ at a high scan rate of 200 mV s⁻¹. Furthermore, it showed remarkable long-term stability, with 84.5% capacitance retention after 5000 cycles. These findings establish the Aloe vera-derived MnCo₂O₄ as a green-engineered, high-rate capable, and durable electrode material for hybrid supercapacitor applications.