Sol–Gel synthesis of Co3O4 nanoparticles as an electrode material for supercapacitor applications (original) (raw)
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Pseudocapacitance Properties of Co3O4 Nanoparticles Synthesized Using a Modified Sol-Gel Method
Materials Research, 2018
This work reports the synthesization of nanoparticles cobalt oxide (Co 3 O 4) with no secondary phase by a modified sol-gel method and its structural morphological and electrochemical characterizations. FTIR, XRD and Raman analysis showed the formation of spinel cobalt oxide with no secondary phase. TEM images revealed that an undefined morphology with average crystallite size estimated by Scherrer's equation was found to be 30 nm. Experiments of cyclic voltametric, galvanostatic chargedischarge and impedance spectroscopy were evaluated at 1 mol L-1 KOH and revealed an intrinsic pseudocapacitance. The studies of complex capacitance and complex power revealed the resistive and capacitive characteristics with a specific capacitance of 120 F g-1 .
IOP Conference Series: Materials Science and Engineering, 2017
In this work, Co 3 O 4 nanoparticles were synthesized by hydrothermal method at different temperatures. The synthesized Co 3 O 4 nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS) and nitrogen adsorption-desorption. The Co 3 O 4 nanoparticles prepared at the hydrothermal temperature of 140 ℃ and at the annealing temperature of 350 ℃ have a shorter crystal spacing distance associated to the (220) crystal planes, larger BET surface area and more bivalent cobalt on the surface than these of Co 3 O 4 nanoparticles prepared at higher hydrothermal temperature or higher annealing temperature. The supercapacitor performances of synthesized Co 3 O 4 nanoparticles were analysed by cyclic voltammograms (CVs), Galvano static charge/discharge (GCD) and the electrochemical impedance spectroscopy (EIS) in 6 M KOH aqueous electrolyte solution. The Co 3 O 4 nanoparticles produced at lower temperatures exhibit good pseudo capacitance behaviour. Also, owning to the low hydrothermal temperature and the annealing temperature of Co 3 O 4 nanoparticles, they can be relatively low cost in favour of a promising candidate for electrochemical supercapacitors.
Cubic spinel Co 3 O 4 nanoparticles with spherical (0D) and hexagonal platelet (2D) morphologies were synthesized using a simple solvothermal method by tuning the reaction time. XRD and HRTEM analyses revealed pure phase with growth of Co 3 O 4 particles along [111] and [110] directions. UV−vis studies showed two clear optical absorption peaks corresponding to two optical band gaps in the range of 400−500 nm and 700−800 nm, respectively, related to the ligand to metal charge transfer events (O 2-→ Co 2+,3+ ). Under the electrochemical study in two electrode assembly system (Co 3 O 4 /KOH/ Co 3 O 4 ) without adding any large area support or a conductive filler, the hexagonal platelet Co 3 O 4 particles exhibited comparatively better characteristics with high specific capacitance (476 F g −1 ), energy density 42.3 Wh kg −1 and power density 1.56 kW kg −1 at current density of 0.5 Ag −1 , that suited for potential applications in supercapacitors. The observed better electrochemical properties of the nanoporous Co 3 O 4 particles is attributed to the layered platelet structural arrangement of the hexagonal platelet and the presence of exceptionally high numbers of regularly ordered pores.
Synthesis By Sol Gel Method And Characterization Of Co3O4 Nanoparticles
A Co3O4 nanoparticles was synthesized by sol gel technique employed with appropriate reactants.in this case, we used metal salt and Tetrahydrofuran (THF) as starting material and the obtained product were calcined at 500 0 C & 550 0 C.the prepared nanoparticles were characterized by XRD, SEM, EDAX. Particle structure was confirmed by x-ray diffraction analysis; size was determined by Scherrer formula. SEM analysis showed that prepared nanoparticles were in Nano regime, somewhat round shaped and interlinked with each other. EDAX analysis showed that composition obtained was near stoichiometry.
Journal of Materials Engineering and Performance, 2018
A simple hydrothermal process was used to design self-assembled Co 3 O 4 nanoparticles in nanorod structure in the presence of graphene oxide as a template. The as-prepared Co 3 O 4 sample in a loose powder form was calcined at 450°C to get the well-crystalline phase of the same compound. The obtained Co 3 O 4 powder sample was characterized by using the powder XRD and SEM. The XRD pattern shows totally nine distinct reflection peaks of (111), (220), (311), (222), (400), (422), (511), (440), and (533) planes. The most intense peaks were chosen to evaluate the structural parameters. The lattice parameters (a), volume (V), and density (q) of the samples are 8.09 Å , 529.47 Å 3 , 6.06 g/cc, which are comparable to the value of lattice parameter (a = 8.056 Å), volume (V = 528.30 Å 3), and density (q = 6.055 gm/cc) for bulk Co 3 O 4. The average size of the Co 3 O 4 nanoparticles is 14 nm which is smaller than the SEM size of 50 nm corresponding to the agglomeration of tiny particles. Further, the formation of Co 3 O 4 nanoparticles were also confirmed by obtaining the band at 569, 1334,1337, 1566, and 3397 cm 21 in FTIR spectrum. Totally five characteristics peaks from Co 3 O 4 at 182.57, 456.49, 505.84, 605.80, and 618.02 cm 21 and peaks from GO-Co 3 O 4 at 182.57, 483.44, 505.84, 605.80, and 618.02 cm 21 corresponding to F 2g , E g , F 2g , F 2g, and A g modes of the crystalline Co 3 O 4 , respectively, in the Raman spectra. In the case of GO-Co 3 O 4 composite, lowintensity peaks of D and G bands are observed. The specific capacitance in rGO-Co 3 O 4 nanocomposite is about 65.15 Fg 21 .
Fabrication and Characterization of Nanoporous Co Oxide (Co3O4) Prepared by Simple Sol-gel Synthesis
Physical Chemistry Research, 2016
Cobalt oxide (Co 3 O 4) nanorods were prepared by a simple co-precipitation method using ethanol solution of cobalt nitrate as precursor and cetyl trimethylammonium bromide (CTAB) as surfactant. Morphological properties of the nanoparticles were characterized. XRD measurement exhibited the structure of Co 3 O 4 nanocrystals for annealed samples. The SEM images revealed that the particles changed from spherical shape to rod-like shaped by increasing annealing temperature. The TEM results exhibited that the size of cobalt oxide nanoparicles decreased from 25 nm for as-made particles to 50 nm for annealed samples with increasing temperature. The FTIR analysis confirmed the functional group presents in the cobalt oxide nanoparticles. The sharp peaks in FTIR spectrum determined the purity of Co 3 O 4 nanoparticles and existence of CoO group. Absorbance peak of UV-Vis spectrum showed the band gap energy of 3.69 eV corresponding to wavelength about 335 nm for as-prepared samples and the band gap energy of 3.49 eV corresponding to wavelength about 355 nm for annealed Co 3 O 4 nanoparticles. The results of magnetic measurements indicated a good coercive field and saturation magnetism around 447.81 G and 17.295 emu g-1 , respectively.
RSC Advances
In a reaction between cobalt (II) and ammonium oxalate in the presence of CTAB or F-127 as surfactant to control the particles size, the cobalt oxalate complex was formed. The precipitate was calcined and the resulted nano cobalt oxide was characterized by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) methods. The crystalline pure and nano-sized particles had an average size of less than 40 nm. Electrochemical properties were examined by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. A maximum specific capacitance of 351 F g −1 was obtained at a scan rate of 0.85 A g −1 in 2 M of KOH solution for Co 3 O 4 @Ni foam electrode (Co 3 O 4 @NF). Furthermore, the electrode exhibits excellent cycle life stability, and almost 98.6% of its initial specific capacitance was maintained after 1000 cycle tests.
Nanomaterials (Basel, Switzerland), 2017
A facile hydrothermal route to control the crystal growth on the synthesis of Co₃O₄ nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co₃O₄ nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co₃O₄ synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes.
CoO and Co3O4 nanoparticles with a tunable particle size
Ceramics International, 2014
In this work we described a simple method of CoO and Co 3 O 4 nanoparticles synthesis with the tunable particle size. Nanoparticles were prepared by thermal decomposition of cobalt glycerolate in a controlled oxygen/nitrogen atmosphere for 1 h in the temperature range from 450 1C to 650 1C. Cobalt glycerolate was prepared by the reaction of cobalt nitrate with glycerol under reflux for 4 h. Obtained nanoparticles were analyzed by X-Ray diffraction to obtain information about their phase composition and average particle size, which was calculated using the Scherrer equation. Scanning electron microscopy and transmission electron microscopy were also used to confirm the particle sizes. Cobalt oxides nanoparticles with defined size can be prepared only by changing of the decomposition temperature of cobalt oxides precursors. The prepared nanoparticles can be used as sensors, in lithium-ion batteries, or in various nanoelectric devices.