Solution synthesis of nanometric layered cobalt oxides for electrochemical applications (original) (raw)
Related papers
2018
Crystalline β-cobalt hydroxide (β-Co(OH)2) of different morphologies have been successfully synthesized with the addition of sodium hydroxide to cobalt nitrate solution and aging in the mother liquor. The rate of NaOH addition, ranging from 0.1 mL/min to 10 mL/min, influences the surface morphology with the obtained storage capability of the respective electrode. Characterization of the β-Co(OH)2 was fully developed, including X-ray diffraction, scanning and transmission electron microscopy, and BET analyses. At a lower rate of NaOH addition, particles are like platelets, while for a higher rate (≥2 mL/min) grains are fused together forming a larger crystallite size. This result is supported by the X-ray diffraction structural analysis, where the phase evolution of (002) plane becomes distinct for the higher rate of NaOH addition. Lithium cobalt oxide (LiCoO2) was synthesized through oxidation from the as-prepared β-Co(OH)2 and LiOH. The electrochemical perfor...
Nanostructured Materials, 1999
Cobalt oxide was prepared from synthetic cobalt nitrate solutions through two step process; electrolysis of cobalt nitrate solution to produce cobalt hydroxide and then preparation of cobalt oxide by calcination of cobalt hydroxide. Cathodic reduction of cobalt nitrate solution at pH ~4 with a cobalt concentration of 28g/L at a current density of 200A/m 2 lead to formation of β-Co(OH) 2 with a current efficiency of 41%. On increasing current density, the current efficiency has increased and reached a maxima of 59% at an applied current density of 500 A/m 2. The effect of Co(II) concentration was studied and found that with increase in Co(II) concentration from 28g/ L to 42 g/L the current efficiency increased to 59% at an applied current density of 200 A/m 2. The β-cobalt hydroxide when calcined at 300°C the corresponding β-Co 3 O 4 was obtained. The morphology and structure of both the cobalt hydroxide and oxide were characterized by scanning electron microscope (SEM) and X-ray diffractometer (XRD) and the discharge capacity of cobalt oxide was measured.
Cobalt oxide preparation from waste LiCoO 2 by electrochemical–hydrothermal method
Journal of Power Sources, 2002
Cobalt ions, extracted from waste LiCoO 2 by using a nitric acid leaching solution, are potentiostatically transformed into cobalt hydroxide on a titanium electrode and cobalt oxide is then obtained via a dehydration procedure. In linear sweep voltammetry, distinct cathodic current peak is observed and indicates that hydroxide ions are formed near the electrode via the electroreduction of dissolved oxygen and nitrate ions give rise to an increase in the local surface pH of the titanium. Under appropriate pH conditions, island-shaped cobalt hydroxide is precipitated on the titanium substrate and heat treatment of the cobalt hydroxide results in the formation of cobalt oxide. #
The thermal decomposition and microwave heating of Co 3 [Co(CN) 6 ] 2 leads to formation of nanostructured porous cobalt oxide (Co 3 O 4 ). Here, we report Co 3 [Co(CN) 6 ] 2 as a novel single source precursor for the synthesis of phase pure Co 3 O 4 particles at 650°C under mixed argon/oxygen atmosphere as evidenced from X-ray diffraction (XRD) patterns. During thermal decomposition, release of gaseous products like CO 2 , N x O y , (CN) 2 facilitate the formation of a highly porous Co 3 O 4 whose morphology and particle size distribution were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. Porous Co 3 O 4 shows high discharge capacity of 1131 mA h g À 1 with 96% coulombic efficiency against Li/Li þ reference electrode.
Materials Technology, 2020
Ni 1-x Co x O 1-δ (Where x = 0.01, 0.03, 0.05, 0.07, 0.09) (CNO) based nanostructured materials were synthesized by facile soft chemical route and characterised for application as electrodes in electrochemical supercapacitors. The prepared materials were studied by XRD, FITR, particle size, EDAX equipped with SEM, TEM and electrochemical studies such as CV, GCD and impedance analysis. XRD has confirmed the presence of the FCC crystalline structure. FTIR results have shown peaks at ~450 cm −1 which are relevant to metal oxide. The existence of nanosized particles were confirmed by particle size measurements. SEM analysis has further shown the appearance of spherical-shaped particles with average grain size ranging from 19.7 to 37.74 nm in the samples. The EDAX data has reflected the occurrence of appropriate elements as per stoichiometry calculations. The TEM analysis carried-out on Ni 0.91 Co 0.09 O 1δ has confirmed the presence of polycrystalline behaviour. Among the samples, Ni 0.91 Co 0.09 O 1δ electrode material has achieved more capacitance (338.13Fg −1).
Electrochimica Acta, 2012
Layered materials Li1.2(Mn0.32Ni0.32Fe0.16)O2 Cobalt free cathodes Li2MnO3 Solid solution a b s t r a c t Cobalt free, eco-friendly layered Li 1.2 (Mn 0.32 Ni 0.32 Fe 0.16 )O 2 compounds were synthesized using the adipic acid assisted sol-gel method. The structure and morphology of the prepared materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The XRD results revealed that all of the materials possess a layered ␣-NaFeO 2 structure with R3m space group. The TEM images confirmed the presence of carbon on the surface of the synthesized material.
Journal of Applied Electrochemistry, 1991
The application of a periodic perturbing potential to a cobalt electrode immersed in alkaline solutions at room temperature allows accumulation of a hydrous cobalt hydroxide overlayer which becomes a precursor to the production of a rough Co3 04 spinel film through subsequent thermal treatment at 480 ~ C. The optimal working conditions for the application of this procedure are discussed. The properties of the resulting overlayers were determined through voltammetry, X-ray analysis, infrared spectroscopy, thermal gravimetric and differential thermal analysis, and SEM micrography. The explanation of the entire process is given in terms of sequential electrochemical oxidation and reduction reactions involving different Co-containing species. The electroreduction reactions including the HER, play an important role in determining the characteristics of the resulting Co304 overlayer.
Electrochemical Performance of Iron-Doped Cobalt Oxide Hierarchical Nanostructure
Processes
In this study, hydrothermally produced Fe-doped Co3O4 nanostructured particles are investigated as electrocatalysts for the water-splitting process and electrode materials for supercapacitor devices. The results of the experiments demonstrated that the surface area, specific capacitance, and electrochemical performance of Co3O4 are all influenced by Fe3+ content. The FexCo3-xO4 with x = 1 sample exhibits a higher BET surface (87.45 m2/g) than that of the pristine Co3O4 (59.4 m2/g). Electrochemical measurements of the electrode carried out in 3 M KOH reveal a high specific capacitance of 153 F/g at a current density of 1 A/g for x = 0.6 and 684 F/g at a 2 mV/s scan rate for x = 1.0 samples. In terms of electrocatalytic performance, the electrode (x = 1.0) displayed a low overpotential of 266 mV (at a current density of 10 mA/cm2) along with 52 mV/dec Tafel slopes in the oxygen evolution reaction. Additionally, the overpotential of 132 mV (at a current density of 10 mA/cm2) and 109 mV...
Cobalt Oxide Nanomaterials by Vapor-Phase Synthesis for Fast and Reversible Lithium Storage
The Journal of Physical Chemistry C, 2010
The design and assembly of suitable nanosystems are key issues in the development of smaller and more efficient lithium batteries. To this regard, cobalt oxides possess very favorable properties for use as negative electrode materials. In this work, we describe a convenient synthesis route to cobalt oxide nanomaterials (both single-and mixed-phase CoO and Co 3 O 4 ) supported on Ti. The systems are grown by chemical vapor deposition starting from an innovative second-generation molecular source, Co(hfa) 2 · TMEDA (hfa ) 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate, TMEDA ) N,N,N′,N′-tetramethylethylenediamine). Controlled variations of the substrate temperature and O 2 pressure in the reaction atmosphere enabled tailoring both the phase composition and the system morphology. The electrochemical properties of the obtained nanosystems were evaluated by galvanostatic measurements and impedance spectroscopy. The results showed excellent cycling performances and very high specific capacity values, offering attractive perspectives for the use of the present systems as advanced anode materials in Li-ion batteries.