TiO2-Co3O4 Core-Shell Nanorods: Bifunctional Role in Better Energy Storage and Electrochromism

Abstract

A suitably designed heterostructured TiO2-Co3O4 core-shell nanorod array has been found to exhibit improved supercapacitive as well as electrochromic properties as compared to the nanowires of either of the oxides when used individually. The core-shell nanostructures have been grown on an FTO coated glass substrate by preparing TiO2 nanorods through hydrothermal reaction followed by growing a Co3O4 shell layer by electrodeposition. The core-shell electrode shows high specific and areal capacitance of ∼342 F/g and ∼140 mF/cm2 (at scan rate of 100 mV/s), respectively. Such an improvement in supercapacitive behavior, as compared to the behavior of the existing ones, is likely due to increased surface area and modified charge dynamics within the core-shell heterojunction. Additionally, these core-shells also exhibit stable and power efficient bias induced color change between transparent (sky blue) and opaque (dark brown) states with coloration efficiency of ∼91 cm2/C. Porous morphology and strong adhesion to the surface of transparent conducting glass electrode give rise to superior cyclic stability in both energy storage and electrochromic applications, which make these core-shell structures suitable candidates for future electronic devices. © 2018 American Chemical Society.