Abstract
•Morphology altered, Chrysanthemum to Marigold -flower like ZnO/ZnCo2O4 composite.•Non-stoichiometry of the elements in ZnO/ZnCo2O4 composites were quantified.•At low-reaction time synthesized composite exhibited a higher specific capacitance, 705.1 F g−1 (@ 0.3 A g−1).•The composite has shown ~ 90% of its initial specific capacitance over 2500 cycles.
Strategic way of regulating and changing the morphological structures of metal oxides always direct to be contributed with different electrochemical properties for redox reactions in energy storage systems. Here in, we have engineered the morphologically controlled zinc cobaltite and zinc oxide (ZnO/ZnCo2O4) composite via an in situ solvothermal route. By varying the reaction time of the solvothermal synthesis, the morphology of the composite has significantly been transformed from Chrysanthemum to Marigold -flower like ZnO/ZnCo2O4 composite. The morphological variations are identified by scanning electron microscopy (SEM) images. The two phases of composites are quantified by refinement of X-ray diffraction data and is endorsed by X-ray photoelectron spectroscopy. By using these two analyses, the non-stoichiometry of the elements (Zn, Co and O) have quantified. Two composites not only demonstrate different physico-chemical properties but also contribute different electrochemical properties. Low reaction time synthesized ZnO/ZnCo2O4 composite has shown higher specific capacitance than the higher reaction time synthesized composite. The ZnO/ZnCo2O4 composite indicates specific capacitance of 705.1 F g−1 (at 0.3 A g−1), which is due to the Co-rich, higher surface area and lower charge transfer resistance of the low reaction time synthesized composite against the counterpart.