Abstract
CoO–ZnO-based composites have attracted considerable attention for the development of energy storage devices because of their multifunctional characterization and ease of integration with existing components. This paper reports the synthesis of CoO@ZnO (CZ) nanostructures on Ni foam by the chemical bath deposition (CBD) method for facile and eco-friendly supercapacitor applications. The formation of a CoO@ZnO electrode functioned with cobalt, zinc, nickel and oxygen groups was confirmed by X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), low and high-resolution scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analysis. The as-synthesized hierarchical nanocorn skeleton-like structure of a CoO@ZnO-3h (CZ3h) electrode delivered a higher specific capacitance (Cs) of 1136 F/g at 3 A/g with outstanding cycling performance, showing 98.3% capacitance retention over 3000 cycles in an aqueous 2 M KOH electrolyte solution. This retention was significantly better than that of other prepared electrodes, such as CoO, ZnO, CoO@ZnO-1h (CZ1h), and CoO@ZnO-7h (CZ7h) (274 F/g, 383 F/g, 240 F/g and 537 F/g). This outstanding performance was attributed to the excellent surface morphology of CZ3h, which is responsible for the rapid electron/ion transfer between the electrolyte and the electrode surface area. The enhanced features of the CZ3h electrode highlight potential applications in high performance supercapacitors, solar cells, photocatalysis, and electrocatalysis.
Highlights
IntroductionWith the increasing energy and power demands of the modern world, the continuous depletion of fossil energy and the continuous growth of the global economy has prompted considerable interest in the generation of renewable, clean and efficient energy ( in terms of the management, storage, and production of this precious energy) [1,2,3,4]
In recent years, with the increasing energy and power demands of the modern world, the continuous depletion of fossil energy and the continuous growth of the global economy has prompted considerable interest in the generation of renewable, clean and efficient energy [1,2,3,4]
Among the electrical energy storage, ultra-capacitors have fascinated researchers and received enormous industrial attention because of their high charge–discharge current capability, high power density, very high efficiency, stable cycling performance, environmentally friendly nature and extensive temperature range compared to fuel cells [5]
Summary
With the increasing energy and power demands of the modern world, the continuous depletion of fossil energy and the continuous growth of the global economy has prompted considerable interest in the generation of renewable, clean and efficient energy ( in terms of the management, storage, and production of this precious energy) [1,2,3,4]. Among the electrical energy storage, ultra-capacitors have fascinated researchers and received enormous industrial attention because of their high charge–discharge current capability, high power density, very high efficiency, stable cycling performance, environmentally friendly nature and extensive temperature range compared to fuel cells [5]. Major research has been directed towards the progression of supercapacitors with minimal sacrifice of the very high energy density and long cycling stability [8,9]. Supercapacitors are used widely in high power applications such as portable electronic devices, renewable energy storage devices, and hybrid electric vehicles [10]. Continuous research has been concerned with designing long cycling performance electrode materials with stability, electrolyte and assembly technology [12,13,14]. The study of electrode materials has become a field of intense research activity [15]
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