Aloe Vera-Assisted Synthesis of MnCo 2 O 4 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 MnCo 2 O 4 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 m 2 g -1 and a dominant pore size around 10 nm, supporting rapid ion transport and efficient electrolyte access. XPS spectra revealed the coexistence of Mn 3 ⁺/Mn 4 ⁺ and Co 2 ⁺/Co 3 ⁺ 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 high scan rate of 200 mV s -1 . Furthermore, it showed remarkable long-term stability. These findings establish the Aloe vera-derived MnCo 2 O 4 as a green-engineered, high-rate capable, and durable electrode material for hybrid supercapacitor applications.