Synergistic effect in the heterostructure of ZnCo2O4 and hydrogenated zinc oxide nanorods for high capacitive response

Abstract

Herein, a novel heterostructure was fabricated by combining electrochemically and optically active materials to achieve a high capacitive response of 896 F g⁻¹ at 5 A g⁻¹. A network of ZnCo₂O₄ nanorods (NRs) was directly grown on a three-dimensional matrix of H : ZnO NRs (ZnCo₂O₄/H : ZnO NRs) that offered synergistic advantages by providing an optimum ion/charge transportation path, large electrochemically active surface area, and stable capacitive response during the electrolytic process. Furthermore, the fabricated solid-state asymmetric supercapacitor ZnCo₂O₄/H : ZnO NRs//activated carbon induced a large potential window of 1.5 V that offered excellent energy and power densities. In addition, optically active ZnCo₂O₄/H : ZnO NRs were also used for the conversion of optical energy over a broad wavelength range; thus, the as-fabricated asymmetric solid-state supercapacitor could easily provide the required power for the operation of a photodetector. Therefore, the unique heterostructure of ZnCo₂O₄/H : ZnO NRs not only presents excellent capacitive response but also demonstrates great potential for energy conversion.