Morphologically tailored NiMn2O4nanocubic material for high energy-power density asymmetric supercapacitor and non-enzymatic H2O2 sensing

Abstract

Developing an advanced material for energy storage and sensors is considered a key solution to meet future energy demands and economic challenges. The inverse spinel-structured NiMn2O4 emerges as a promising electrode material for next-gen energy storage due to its notable power capability, high energy density, and excellent cyclic stability. Nanostructuring enhances features not achievable in bulk materials, with a mixed morphology of nano-cubic and nanoflakes optimizing surface-to-volume ratio for effective use in energy storage devices. The addition of PVP as a surfactant, transforms the diffusion-controlled behavior to a capacitive mechanism, enhancing energy density and cyclic stability. Electrodes exhibit a specific capacitance of 816 F g−1 at 1 A g−1 and stable cyclic behavior over 5000 cycles in 1 M KOH. The constructed ASC device shows 96% cyclic stability over 10,000 cycles, maintaining an energy density of 8.8 Wh kg−1 at 6400 W kg−1 and reaching a maximum of 36.55 Wh kg−1 at 400 W kg−1. Electronic structural characteristics explained through density functional theory (DFT) contribute insights. Furthermore, the non-enzymatic NiMn4/GCE H2O2 sensor demonstrates high sensitivity, a low detection limit, and remarkable selectivity against various biological interferences across a broad concentration range.