High-entropy oxide (CaCu₃Ti_3.85Mn_0.05Sn_0.1O₁₂) as a multifunctional electrocatalyst for supercapattery and water...

In this study, a high-entropy oxide (CaCu₃Ti_3.85Mn_0.05Sn_0.1O₁₂) was synthesized via a semi-wet route, playing a crucial role in advancing multifunctional electrocatalysis. Pre- and post-XPS analyses revealed synergistic interactions among the multi-cation 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.