Improved Electrochemical Performance of Aqueous Hybrid Supercapacitors Using CrCo<sub>2</sub>O<sub>4</sub> Mesoporous Nanowires: An Innovative Strategy toward Sustainable Energy Devices
Awais Ahmad, Safia Khan, Muhammad Sufyan Javed, Sameh M. Osman, Hu Li, Saadat Majeed, Rafael Luque
Abstract
High-rate aqueous hybrid supercapacitors (AHSCs) have attracted relevant scientific significance owing to their expected energy density, supercapacitor-level power density, and battery-level energy density. In this work, a bimetallic nanostructured material with chromium-incorporated cobalt oxide (CCO, i.e., CoCr 2 O 4 ) was prepared via a hydrothermal method to form a stable cubic obelisk structure. Compared with CCO materials prepared using traditional methods, CCO displayed a nanowire structure (50 nm diameter), suggesting an enhanced specific surface area and a large number of active sites for chemical reactions. The electrode possessed a high specific capacitance (2951 F g –1 ) at a current density of 1 A g –1, minimum R ct (0.135 Ω), and the highest capacitance retention (98.7%), making it an ideal electrode material for AHSCs. Ex situ analysis based on X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed a favorable stability of CCO after 10,000 cycles without any phase changes being detected. GGA and GGA + U methods employed in density functional theory (DFT) also highlighted the enhanced metallic properties of CCO originating from the synergistic effect of semiconducting Cr 2 O 3 and Co 3 O 4 materials.