Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors

Abstract

Nanoporous/cracked structures of cobalt oxide (Co 3 O 4 ) electrodes were successfully fabricated by electroplating of zinc-cobalt onto previously formed TiO 2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400°C. The structure and morphology of the obtained Co 3 O 4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co 3 O 4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co 3 O 4 electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 1 M NaOH solution. The electrochemical data demonstrated that the electrodes display good capacitive behavior with a specific capacitance of 430 F g -1 at a current density of 1.0 A g -1 and specific capacitance retention of ca. 80 % after 10 days of being used in electrochemical experiments, indicating to be promising electroactive materials for supercapacitors. Furthermore, in comparison with electrodes prepared by simple cathodic deposition of cobalt onto TiO 2 nanotubes(without dealloying procedure), the impedance studies showed improved performances likely due to nanoporous/cracked structures of electrodes fabricated by dealloying of zinc, which provide fast ion and electron transfer routes and large reaction surface area with the ensued fast reaction kinetics.

Electrochemical Studies of Inkjet Printed Semi-Transparent NiCo2O4/ITO Supercapacitor Electrodes

“…The near-linear rise of the curve at lower frequencies could either be assigned to a Warburg impedance (associated to a diffusion process, most likely the transport of OH − ions within the pores of NCO electrodes during the redox reactions) or to a constant phase element CPE with an n value close to 0.5 (associated to a circuit element intermediate between a resistor and a capacitor, in line with the hybrid supercapacitor behavior of the material). Fitting an appropriate electrical circuit to the data ([R u (R p CPE p )([R ct W]CPE dl )]; inset of Figure 16) accounts for the above-mentioned processes and is also similar to those appearing in the literature [41,42]. Estimated values of the circuit components are presented in Table 2, and an interpretation follows.…”

Enhanced solar-driven photoelectrochemical water splitting using nanoflower Au/CuO/GaN hybrid photoanodes

“…57–59 Generally, CPE may manifest as a result of (i) the nature of the electrode, (ii) porosity, and (iii) the inhomogeneity of the electrode–electrolyte interface. 60,61 CPE is described in eqn (8): 62 where CPE T and CPE P are constants that are independent of frequency and w represents the angular frequency. The constant phase element is identified by two values of CPE T and CPE P .…”

“…The capacitance corresponding to the double layer formed between the active electrode and the electrolyte can be indicated by the constant phase element (CPE) [57][58][59]. Generally, CPE may manifest as a result of (i) the nature of the electrode, (ii) porosity, and (iii) the inhomogeneity of the electrode-electrolyte interface 60,61. CPE is described in eqn (8): 62 CPE T and CPE P are constants that are independent of frequency and w represents the angular frequency.…”

Effect of Time on a Hierarchical Corn Skeleton-Like Composite of CoO@ZnO as Capacitive Electrode Material for High Specific Performance Supercapacitors

“…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 (particularly 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].…”