High-Entropy Oxide (CaCu 3 Ti 3.85 Mn 0.05 Sn 0.1 O 12 ) as a Multifunctional Electrocatalyst for Supercapattery and Water Electrolysis

Abstract

In this study, a high-entropy oxide (CaCu3Ti3.85Mn0.05Sn0.1O12) was synthesized via semi wet route method playing a crucial role in advancing multifunctional electrocatalysis. Pre- and post-XPS analyses revealed a synergistic interaction among multication species, while Raman spectroscopy indicated enhanced crystallinity and atomic stabilization. HR-TEM/SEM/EDS and elemental mapping confirmed a homogeneous composition, characterized by densely agglomerated clusters intertwined with thread-like crystalline structures that promote redox transitions and facilitate active oxygen participation. The HEO electrode exhibited a high specific capacitance of 681.3 F g-1 at 1 A g-1, along with an energy density of 17.5 Wh kg-1 and a power density of 214.2 W kg-1 at the same current density. Furthermore, the material demonstrated outstanding bifunctional electrocatalytic performance in water splitting, achieving a low overpotential of 130 mV vs RHE at 10 mA cm-2 with a Tafel slope of 83.3 mV dec-1 for the OER, and 201 mV vs RHE with a Tafel slope of 185.7 mV dec-1 for the HER. Detailed investigations of charge-transfer dynamics provided insight into the structure performance relationship, supported by thermodynamic and kinetic analyses to determine the activation enthalpy and reaction order. Overall, the study highlights the immense promise of HEOs for integrated energy storage and conversion applications, contributing to the development of sustainable energy technologies.