In situ engineered 0D interconnected network-like CNS decorated on Co-rich ZnCo2O4 2D nanosheets for high-performance supercapacitors

Abstract Co-rich ZnCo2O4 (ZCO) two-dimensional (2D) nanosheets are decorated with highly porous, glucose-derived, zero-dimensional (0D) interconnected network-like carbon nanospheres (CNS) using an in situ hydrothermal method. The content of CNS in the reaction is varied to produce two different composites (CNS@ZCO-I and CNS@ZCO-II). Their physicochemical properties are examined and compared with those of the pristine-CNS and ZCO samples. The non-stoichiometry of the elements in ZCO of the composites is quantified by X-ray diffraction using a Reitveld refinement and X-ray photoelectron spectroscopy. CNS@ZCO-II is found to be Co-rich in ZnCo2O4 compared to the other samples. The high surface area of the CNS and non-stoichiometry of Zn/Co in the composites provide a short ion/electron transport path distance, high electronic conductivity, additional electrochemical active sites, and stable structural integrity. This viable strategy offers a good interaction between the CNS and ZCO, which translates to better electrochemical activity as an electrode material for energy storage devices. The CNS@ZCO-II composite with a higher CNS concentration shows an excellent electrochemical performance of approximately 1116.24 F g−1 at 0.35 A g−1 (compared to the pristine-ZCO and CNS@ZCO-I composite).