Exploring nanoscale engineering for elevated electrochemical performance: A multiscale experimental and computational investigation of Co3O4@TiO2 nanocomposites

Abstract

The novelty of this work lies in the utilization of Co₃O₄@TiO₂ as a supercapacitor material, where Cobalt's abundance offers a sustainable and cost-effective source, while titanium's lightweight nature enhances the energy density. Together, this composite achieved an impressive power density of 4284 W kg⁻¹ and energy density of 32.6 Wh·kg⁻¹ at a current density of 1.7 A g⁻¹, demonstrating its high-performance capabilities in energy storage application. The Co₃O₄@TiO₂ composite was successfully prepared using a sequential process involving centrifugation, and calcination for Co₃O₄ nanopill synthesis, while TiO₂ nanofibers were synthesized using a hydrothermal reaction followed by centrifugation and calcination. X-ray diffraction (XRD) analyses in conjunction with Scanning electron microscopy (SEM) detect the well-embedded Co₃O₄ nanopills, TiO₂ nanofibers, and their phases within the composite structure. The composite achieves an exceptional specific capacitance of 555 F g⁻¹ at 2 A g⁻¹ and maintains 85.7 % capacitance retention at 10 A g⁻¹ after 10,000 galvanostatic charge–discharge (GCD) cycles. Impedance spectroscopy results reveal that the composite exhibits great capacitive behavior, with a series resistance of 0.4 Ω. Furthermore, a Co₃O₄@TiO₂ two-electrode arrangement demonstrates competent cyclic stability after 10,000 cycles. In addition, the Butler-Volmer numerical model is utilized in finite element modeling to simulate the potential distribution and concentration profiles of Co₃O₄²⁺ and Co₃O₄³⁺ ions within a one-dimensional (1-D) electrode-electrolyte configuration, facilitating the analysis of electron transfer kinetics.