Mixture Of CoO Research Articles

Sliding wear-induced compositional lamination in a VCoNi alloy at elevated temperatures, and its implications for reduced friction and wear

During tribological loading of metallic alloys at elevated temperatures, the thermo-mechanical coupling effect can lead to the development of a distinct tribolayer, profoundly influencing their tribological behavior. This study reports on the compositional lamination in the tribolayer during dry sliding wear of a VCoNi multi-principal element alloy at elevated temperatures. As the temperature increases from 25 °C to 600 °C, the alloy exhibits a remarkable 40% reduction in the coefficient of friction and a notable two-order-of-magnitude decrease in wear rate. The compositional lamination at 600 °C reveals a distinct tribolayer comprising a nanocrystalline-amorphous oxide glaze layer, a Ni-rich dealloyed layer, and a plastic deformation layer. Within the oxide glaze layer, three sublayers are identified, each featuring a nanocrystalline-amorphous nanocomposite structure with unique equiaxed nanograins. Specifically, the outermost sublayer comprises Co3O4, the intermediate sublayer contains a mixture of Co3O4 and Ni2V2O7, and the inner sublayer consists of V2O5. This multilayered structure is attributed to significant differences in the chemical affinity for oxygen among the constituent elements and their respective diffusion rates in the oxide scale. Significantly, the tribolayer formed at 600 °C exhibits a remarkable 70% increase in yield strength compared to its formation at 25 °C, correlating with a substantial reduction in wear. These findings present a novel avenue for designing self-adaptive, high-temperature wear-resistant alloys through the in-situ formation of a protective compositionally-laminated tribolayer.

Carbon nanotube as a nanoreactor for efficient degradation of 3-aminophenol over CoOx/CNT catalyst

Nanoreactors have been enlightened by enzymes to benefit from particular confinement for purpose of the acceleration of catalytic reactions and rendering them specific. Herein, we have first designed and synthesized the high-efficiency carbon nanotube-stabilized cobalt oxides nanoparticles (CoOx/CNT), via immobilization of CoOx nanoparticles onto carbon nanotube (CNT), for 3-aminophenol (3-AP) degradation via peroxymonosulfate (PMS) activation. Among them, carbon nanotube is used as a nanoreactor for efficient degradation of 3-AP over CoOx/CNT nanocomposite. The detailed physical characterizations illustrate that CoOx/CNT presented a nanotube-shaped structure, and some CoOx nanoparticles were encapsulated into CNT, and the molar ration of Co and O in CoOx was calculated to be 1:1.006, where CoO1.006 might be the mixture of CoO and Co3O4. The comparison with other carriers (including MoS2, CeO2, ZnO and ZrO2), CoOx/CNT provides the highest 3-AP degradation efficiency, highlighting the key role of CNT, as a nanoreactor, in CoOx/CNT for activating PMS to degrade 3-AP. The super-high catalytic activity of CoOx/CNT nanocomposite in the 3-AP degradation is owing to the specific confinement (encapsulation of some CoOx by carbon nanotubes). It seems the electron transfer from CNT to Co atom surface, enriched its surface electron cloud density, which is favorable for PMS activation. Quenching experiments and electron paramagnetic resonance (EPR) result have verified that SO4•- and OH• are the primary reactive oxygen species in 3-AP degradation over CoOx/CNT/PMS system. This study provides a new research orientation for the synthesis of efficient and stable carbon nanotube-encapsulated Co-based nanocatalyst for wastewater treatment.

CoOx ceramics synthesized by a facile and rapid combustion method and its application for thermochemical energy storage

Cobalt-based ceramics is one of the most promising candidates for thermochemical energy storage. In this paper, a novel cigarette butts assisted combustion synthesis method was proposed to synthesize nano-CoOx ceramics used for thermochemical energy storage. For this method, cigarette butts were selected as solid fuels. The cigarette butts were impregnated in cobalt nitrate solution, and the cobalt nitrate solution was absorbed, filled and dispersed uniformly in the cigarette butts. The wet cigarette butts were directly burned, and two combustion modes (smoldering and flaming) were considered. After the wet impregnated cigarette butts burned out, nano-CoOx was obtained. The commercial and sol-gel method prepared CoOx was also tested for comparison. Based on the characterization results, the CoOx obtained from the combustion synthesis method was a mixture of Co3O4 and CoO. In addition, CoOx synthesized in the smoldering combustion process (S250) had the highest BET specific surface area and better performance on thermochemical energy storage. The conversion rate was kept above 97% and the oxidation rate could maintain at a stable and higher value (∼175 μmol/min/g) after 30 cycles. For S250, the onset temperature gap between heat charging and discharging was the smallest (15.9 °C), suggesting that S250 could charge and discharge quickly and kept a complete reversibility in multiple cycles. The heat loss of S250 was the smallest and its heat grade was the highest. As a whole, direct combustion of the wet impregnated cigarette butts could be a feasible and rapid method to synthesize nano-CoOx ceramics, which exhibited superior performance on thermochemical energy storage.

An infrared study of antiferromagnetic medium and high entropy rocksalt structure oxides

The infrared reflectance of a set of antiferromagnetic entropy-stabilized rocksalt structure oxides is measured in order to study the effect of a random array of cations, spin–phonon coupling, and anharmonicity on phonon mode behavior. Samples were prepared by conventional solid state reaction from quaternary or quinary equimolar mixtures of CoO, ZnO, CuO, NiO, and MgO. They were characterized by magnetometry, x-ray diffraction, and reflectance spectroscopy. It is found that the Néel temperature (TN) depends on the concentration of magnetic ions. The far-infrared reflectance spectra consist of one strong reststrahlen band and a weaker low frequency band, which is unexpected in a rocksalt structure. The resonance frequency of the main transverse optical (ωTO) mode varies between 355<ωTO<386 cm−1 and is controlled by both the average reduced mass of a cation–anion pair and the average effective charge. Unlike the parent compounds CoO and NiO, no splitting of ωTO due to spin–phonon coupling appeared in the reflectance spectra below TN. This is possibly due to the high scattering rate of the associated transverse optical mode, which is connected to static disorder.

Catalytic Plasma Fischer–Tropsch Synthesis Using Hierarchically Connected Porous Co/SiO2 Catalysts Prepared by Microwave-Induced Co-assembly

Catalytic plasma-enhanced Fischer–Tropsch synthesis (FTS) for gas-to-liquid conversion was investigated using a recently developed novel nanostructured, hierarchically connected micro/meso-porous Co/SiO2 catalyst obtained through microwave irradiation-induced coassembly of the catalyst and catalyst support precursors ( Catalysts 2020, 10, 152). This catalyst structure with its micron-scale morphological and chemical heterogeneity is particularly suitable for catalytic plasma reactions. It is shown that a dielectric barrier discharge (DBD) can promote FTS over the catalysts at low temperatures and ambient pressure with 100% conversion without any deactivation over a prolonged time scale (175 h in the current study). In contrast to conventional FTS, the hydrogen conversion is higher in plasma FTS, demonstrating that a DBD can promote FTS for more methane and higher hydrocarbon formation. It is shown that the catalyst is not fully reduced and is a mixture of CoO and Co. Carbon deposition present due to incomplete heat treatment of the catalyst to remove the organic coating on SiO2 support results in catalyst deactivation, which can be eliminated by using high catalyst reduction temperature. Furthermore, the catalytic activity increases during the course of reaction due to the plasma-induced morphological changes in the catalyst structure. In the absence of a plasma, catalyst deactivation is very rapid, which is reversed by burning carbon deposit using DBD plasma in oxygen atmosphere at 150 °C. The results indicate that it is possible to develop a new sustainable, distributed FTS technology operating at low temperatures, ambient pressure, and small scale by optimizing the catalyst property, reactor design, and reaction parameters under plasma conditions.

Spectral analysis on CoOx films deposited by atomic layer deposition

Cobalt oxide (CoOx) films are deposited on SiO2/Si substrates using atomic layer deposition (ALD). The physical properties of CoOx films are characterized by atomic force microscopy (AFM), spectroscopic ellipsometry and X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The O content in the CoOx films deposited at different temperatures are analyzed by XPS, which reveals that the deposited CoOx film is a mixture of CoO and Co3O4. With increasing temperature, surface chemisorbed oxygen species are substantially decreased. The ratio of Co3O4 gradually decreases compared to that of CoO with increasing temperature. Our experimental results reveal that ALD can precisely deposit CoOx film; these materials can potentially be used in the fields of physics, chemistry, materials, green environments and clean energy.

DIRECTED SYNTHESIS OF MIXED-LIGAND-HETEROMETALLIC XYLARATOGERMANATES OF Co(II) WITH 1,10-PHENANTHROLINE / 2,2'-BIPYRIDINE

Coordination compounds with complex cations of Co 2+ with 1,10-phenanthroline, 2,2’-bipyridine and tetrameric xylaratogermanate anion were obtained. Their composition and structure were established by the methods of elemental analysis, IR-spectroscopy and thermogravimetric analysis. In the IR-spectrum of I , II bands of asymmetric υas(COO–) (~1686 cm -1 ) and symmetric υs(COO–) (~ 1442 cm -1 ) valence vibrations of carboxylate groups are presented. The presence of υ(C-O) (~ 1069 cm -1 ) band (alcoholic type) and d(C-OH) (~1144 cm -1 ) band, which is typical for the xylaric acid, indicates that not all hydroxyl groupsof the H 5 Xylar ligand are deprotonated. Absorption bands υ(Ge-O) (~737 cm -1 ), υ as (GeOGe) (~851 cm-1) are also detected. They indicate the binding of germanium to xylaric acid and formation of the Ge-O-Ge bridge. The deformation vibration band of the Ge-О-Н (~821 cm -1 ) indicates the implementation of the hydrolyzed form of germanium. There also appear n(ОН)H 2 O, ns(C–Harom.), ν(C-Carom.), n(C-Narom.), δ(С-H) bands, that are typical for crystallization water molecules and 1,10-phenanthroline ( I ), 2,2’-bipyridine ( II ). The thermal destructions of the both compounds are similar. On the thermograms of both compounds one low-temperature effect is presented at 80-270 °С(for I ) and 80-260 °С (for II ) respectively. According to the temperature of elimination and the weight loss (8,75% for I and 14,5% for II ), crystallization water molecules were calculated ( I – 12, II – 20). Due to the mass loss along the thermogravimetric curve at 900 °C, the final products of thermal destruction is a mixture of CoO + GeO 2 . The molecular formulas of complexes I , II are proposed in the accordance of the results of elemental analysis, IR spectroscopy and thermogravimetric analysis: [Сo(phen) 3 ] 2 [(OH) 2 Ge 2 (m-HXylar) 4 Ge 2 (m-OH) 2 ]∙12Н 2 О ( I ), [Сo(bipy) 3 ] 2 [(OH) 2 Ge 2 (m-HXylar) 4 Ge 2 (m-OH) 2 ]∙20Н 2 О ( II ). Their scheme of structure were suggested.

The role of surface N[sbnd]H groups on the selective hydrogenation of cinnamaldehyde over Co/BN catalysts

The surface chemistry of catalyst plays a vital role in the catalytic process. And the effects of surface groups of porous boron nitride (p-BN) on the hydrogenation reaction have not been studied in detailed. In this work, two main surface species of Co/p-BN catalyst were tuned thermally and their roles on the hydrogenation reaction were discriminated by α, β-unsaturated aldehyde hydrogenation reaction. The surface BO content decreased at higher reduction temperature and the cobalt phase changed from CoO to the mixture of CoO and Co0. The Co/p-BN-500 exhibited the highest selectivity to CO hydrogenation. And its turnover frequency (TOF) of 13.2 h−1 is close to the optimal value of reported cobalt catalysts. When the reaction proceeds, hydrogenation rate of CO increases but that of CC decreases gradually, thus a surface groups variation was expected at the initial period. Further in-situ FTIR spectra showed the band intensity of edge NH increases as the adsorption proceeds at 50°С but it decreases as the temperature rise to 200°С, in combined with the shift of CO adsorption peak, a intermolecular hydrogen bond between edge NH and the terminal CO group was suggested, which account for the better selectivity to CO than CC.

Two-Step Synthesis of Cobalt Oxide Nanowires via Electroless Deposition and Thermal Oxidation for Supercapacitor Applications

Cobalt (Co) nanowires were synthesized via electroless deposition in ethylene glycol under an external magnetic field then oxidized in air via thermal oxidation at 250 to 300 °C. The nanowires have lengths in the range of 10 to 14 µm while the diameter increases with oxidation temperature. This can be attributed to the partial melting of the nanowires during oxidation, resulting to sintering. The peaks in the XRD patterns show complete oxidation of Co nanowires, producing a mixture of Co3O4 and CoO. It was observed that Co3O4 and CoO peaks were more intense at 270 °C. There is a decrease in specific capacitance (F/g) with increase in scan rate due to poor electron exchange between active material electrode and electrolyte. Highest calculated specific capacitance was 339.28 F/g using nanowires oxidized at 270 °C at 1 mV/s scan rate.

Conventional and two step sintering of PZT-PCN ceramics

In this study, PZT-PCN ceramic was made via sol–gel seeding method and effects of conventional sintering (CS) as well as two-step sintering (TSS) were investigated on microstructure, phase formation, density, dielectric and piezoelectric properties. First, high quality powder was achieved by seeding method in which the mixture of Co3O4 and Nb2O5 powder was added to the prepared PZT sol to form PZT-PCN gel. After drying and calcination, pyrochlore free PZT-PCN powder was synthesized. Second, CS and TSS were applied to achieve dense ceramic. The optimum temperature used for 2 h of conventional sintering was obtained at 1150 °C; finally, undesired ZrO2 phase formed in CS procedure was removed successfully with TSS procedure and dielectric and piezoelectric properties were improved compared to the CS procedure. The best electrical properties obtained for the sample sintered by TSS in the initial temperature of T1 = 1200 °C and secondary temperature of T2 = 1000 °C for 12 h.

Promising anode material for lithium-ion cells based on cobalt oxide synthesized by microwave heating

High-performance anode material for lithium-ion cell based on cobalt oxide was synthesized through a combination of sol-gel route and subsequent microwave heating. The influence of microwave irradiation temperature of the precursor on the characteristics of the active materials formed was studied. The physicochemical, structural, and morphological properties of the materials were studied in addition to the electrochemical performance by cyclic voltammetry and charge-discharge cycling vs. Li+/Li. Microwave heating at 350 °C resulted in the formation of Co3O4, whereas at 450 and 550 °C, a mixture of Co3O4, CoO, and Co was formed. Co3O4 synthesized at 350 °C possessed porous morphology with high specific surface area and exhibited superior electrochemical performance with initial specific capacity of 982 mAh g−1 and coulombic efficiency of ~75% along with good cycle performance retaining ~87% of initial capacity after 60 cycles.

Thermodynamic Investigation of Cobalt-Oxide Based Material Systems for Lithium Ion Batteries

Conversion-type electrode materials based on transition metal oxides are promising anode materials for next-generation lithium-ion batteries (LIB) because of their high theoretic specific capacities. However, conversion materials generally suffer from relatively low cycling-stabilities due to the loss of inter-particle contacts which occurs as a result of the conversion reaction. Co3O4 is an interesting conversion material since it exhibits a much higher theoretical specific capacity (890 mAh/g) compared to extensively used graphite (372 mAh/g). In addition, mixtures of Co3O4 with CuO have been shown to lead to further improvements in cycling stability and specific capacity[1]. Since the conversion reaction mechanism is still not well understood, the aim of this work is to use experimental thermodynamics combined with modeling and simulation to better understand the electrochemistry of the conversion reaction for Co3O4. During electrochemical cycling of LIBs, compositional changes and phase transformations of the electrodes take place when lithium ions are added or removed according to the equation: 10 Li+ + Co3O4 + 10 e- ⇌ Li2O + 3 CoO + 8 Li+ + 8 e- ⇌ 3 Co + 4 Li2O. (1) The equilibrium phases and coulometric titration curves during lithiation/delithiation can be calculated using CALPHAD-based thermodynamic descriptions of the multi-component material systems. However, the development of CALPHAD-based thermodynamic descriptions requires reliable thermodynamic and phase diagram data. Thus, in the first step of this work, key thermochemical experiments and phase diagram investigations were performed to clarify inconsistencies in the existing literature data. The enthalpy of reduction of Co3O4 to CoO was determined using high temperature oxide melt and transposed temperature drop calorimetry. This reaction is of particular importance for conversion electrodes because it is an intermediate step in the conversion reaction (see equation (1)). Additionally, since reliable heat capacity data are needed to extrapolate the thermodynamic descriptions to temperatures relevant for battery applications, the heat capacity of Co3O4 in the temperature range of 240 to 1150 K was measured using differential scanning calorimetry. The experimental data were then compared to calculations performed using an existing thermodynamic description of the Co-O system[2] to assess its reliability for extrapolations to higher order systems. Since phase diagram data in the Li-Co system are limited, several intermetallic samples were prepared, heat treated at different temperatures and quenched to room temperature. The samples were subsequently investigated using SEM, powder XRD and ICP-OES. A thermodynamic description of the Li-Co sub-system was developed based on these results and used for a preliminary thermodynamic description of the multi-component Li-Co-O material system. Calculations using the preliminary thermodynamic description were compared to experimentally determined emf and phase diagram data at 673 K from Godshall et al.[3]. Finally, results of electrochemical cycling tests performed in this work using half cells with coin cell geometry were discussed in comparison to calculations from the thermodynamic description of the Li-Co-O material system. [1] D. Wadewitz, W. Gruner, M. Herklotz, M. Klose, L. Giebeler, A. Voss, J. Thomas, T. Gemming, J. Eckert, H. Ehrenberg, J. Electrochem. Soc. 2013, 160, A1333-A1339. [2] M. Chen, B. Hallstedt, L. J. Gauckler, J. Phase Equilib. 2003, 24, 212. [3] N. A. Godshall, I. D. Raistrick, R. A. Huggins, Mat. Res. Bull. 1980, 15, 561.

Site-selective high-resolution X-ray absorption spectroscopy and high-resolution X-ray emission spectroscopy of cobalt nanoparticles.

The special (macroscopic) properties of nanoparticles are mainly due to their large surface-to-volume ratio. Thus, the separate characterization of geometric and electronic properties of surface and bulk would be favorable for a better understanding of the properties of nanoparticles. Because of the chemical sensitivity of X-ray fluorescence lines, in particular those involving higher lying electronic states, high-resolution fluorescence-detected X-ray absorption spectra (HRFD-XAS) offer these opportunities. In this study, three types of wet-chemically synthesized Co nanoparticles, ∼6 nm in diameter with varying thicknesses of a protective shell, were investigated at the ID26 beamline of the European Synchrotron Radiation Facility. HRFD-XAS spectra at the Co K-edge, that is, X-ray absorption near-edge structure (HRFD-XANES) and extended X-ray absorption fine structure (HRFD-EXAFS) spectra, were recorded via detection of the Kβ1,3 fluorescence at specific energies. As these spectra are only partly site-selective due to a strong overlap of the emission lines, a numerical procedure was applied based on a least-squares fitting procedure, realized by singular value decomposition. The detailed analysis of the obtained site-selective spectra, regarding chemical composition and crystallographic phase, using measured and simulated FEFF9-based reference spectra, showed that the metallic core had mainly hexagonal close-packed structure with lattice constants matching bulk Co; the spectra for the shell could be satisfactorily fitted by a mixture of CoO and CoCO3; however, with an obvious need for at least a third compound. To obtain additional information about ligands attached to Co, valence-to-core X-ray emission spectra (VTC-XES) using the Kβ2,5 and the satellite structure Kβ″ and VTC-XANES spectra thereof were also recorded, by which the former results are confirmed. Further on, FEFF simulations indicate that a Co-N compound is a very likely candidate for the third component. The presented results clearly show that VTC-XES and HRFD-XAS are suitable tools for the detailed specification of the core and the surface of nanoparticles, in particular upon realizing "real" site-selectivity for XANES and EXAFS with a general strategy applicable to a wide range of systems.

Cobalt ferrite nanoparticles hosted in activated carbon from renewable sources as catalyst for methanol decomposition

High quality micro-mesoporous activated carbon was prepared from waste bio-mass (peach shells) and used as a host matrix of cobalt ferrite nanoparticles. The obtained materials were characterized by N2 physisorption, XRD, FTIR and Moessbauer spectroscopy and tested as catalysts for hydrogen production from methanol. Depending on the Co/Fe ratio formation of pure CoFe2O4 or a mixture of CoO and ferrite phases were observed for carbon supported bi-component materials, while under the same condition the silica support provides the formation of non-stoichiometric ferrite phase. The catalytic active phase which is formed by the influence of the reaction medium represents a complex mixture of non-changed ferrite, magnetite, Co–Fe alloy and/or Fe3C in different proportions.

Synthesis of hydrosols of oxygen-containing cobalt compounds

A procedure is developed for the synthesis of hydrosols of oxygen-containing cobalt compounds. The hydrosols are stable to aggregation for several weeks in the absence of additional stabilizers. It is established that the synthesized hydrosols contain crystalline particles formed from a mixture of CoO(OH) and Co3O4. According to transmission electron microscopy data, the most probable diameter of the particles is about 30 nm. The hydrosols are stable to aggregation at pH 6.2–8.0. In this pH range, the particles are positively charged and the values of their electrokinetic potential are no higher than 10 mV.

ChemInform Abstract: A New Organically‐Templated Cobalt Borophosphate with a Novel Borophosphatic Anionic Partial Structure.

Abstract(NH4)2(C4H12N2) [Co2B4P6O14(OH)2] ·H2O is hydrothermally synthesized from a mixture of CoO, NH4HB4O7, piperazine, H3PO4, and H2O (autoclave, 473 K, 5 d).

Oxidation Resistance of Co-10Cr-5Si-0.3Y Alloys at 800°C

The effect of the addition of 0.3 at.% Y on high temperature oxidation resistance of ternary Co-10Cr-5Si alloy in 0.1MPa O2 at 800°C was investigated. The addition of 0.3 at.% Y greatly increased the oxidation rate of the alloy and changed the approximate parabolic rate law into linear rate law. The scale formed on Co-10Cr-5Si-0.3Y alloy was double-layered, with formation of an outer layer of CoO and an inner region containing a mixture of CoO, Cr2O3, SiO2 and a trace of yttric oxide, coupled to the internal oxidation region of Si.

X-ray powder diffraction data of layered cobaltites with the compositions Ca3−xSrxCo4O9

Ca3−xSrxCo4O9 with different compositions (x=0, 0.15, 0.3, and 0.45) were synthesized from stoichiometric mixtures of Co3O4, CaCO3, and SrCO3, and their unit-cell parameters were determined. The powders were mixed with silicon standard powder, and XRD patterns were collected and analyzed using TOPAS. The compounds were determined to be monoclinic with space group of P2. Unit-cell parameters changed from a=4.8329(3) Å, b=4.5727(1) Å, c=10.8360(4) Å, and β=98.093(7)° when x=0, to a=4.8432(1) Å, b=4.6100(3) Å, c=10.8668(3) Å, and β=98.110(5)° when x=0.3. An unidentified second phase was observed when x=0.45.

Synthesis, phase study and magnetic characterisation of Co50Fe40Cu10 ternary alloy nanopowders prepared by mechanochemical alloying process

Mechanical milling and hydrogen reduction of pure oxide mixture and magnetic characterisation of Co–Fe–Cu ternary alloy nanopowders were investigated. A powder mixture of Co3O4, CuO and Fe2O3 with Co50Fe40Cu10 stoichiometry was first milled by a high energy planetary ball mill and then reduced in a hydrogen reduction system.The optimum condition of the reduction under the hydrogen atmosphere was 650°C and 1 h. The X-ray diffraction patterns exhibit that the powder has ordered bcc structure with b2–bcc space group and 2·87 Å lattice parameter. Mean crystallite sizes calculated from X-ray diffraction results and mean particle size observed from electron microscopes were over 75 nm. Magnetic evaluation of ternary alloy nanopowders showed a saturation magnetisation value about 143 Am2 kg–1 and a low coercivity value of 0·93 Am–1.

Synthesis, Crystal Structure and Thermal Decomposition Character of an Environmentally‐Friendly Energetic Coordination Compound of [Co(NH3)4(NO3)](NO3)·0.5H2O

AbstractA new coordination compound of [Co(NH3)4(NO3)]NO3·0.5H2O was synthesized by reacting Co(NO3)2 with NH3·H2O aqueous solution. It has been characterized by using elemental analysis, FT‐IR technology, and X‐ray single crystal diffraction analysis. It belongs to the monoclinic crystal system and P(2)/n space group with the unit cell: a=0.74618(1) nm, b=2.26114(4) nm, c=1.04282(2) nm, β=92.038(1) °. The central ion Co(II) displays a stable octahedral configuration, which was constructed with the central ion Co(II), four nitrogen atoms from NH3 molecules and two oxygen atoms from NO−3. The outer sphere was NO−3 and a common crystalline water molecule, which connected the inner sphere by electrostatic force and the intermolecular force. The intermolecular and intramolecular hydrogen bonds constructed a three‐dimensional network structure, which increased the stability of the whole crystal structure. In addition, thermal decomposition character of the title complex was investigated by using TG‐DTG, DSC and FT‐IR technologies. There are two endothermic peaks and one exothermic one in the process of thermal decomposition, and the decomposition residue at 300°C is the mixture of CoO and Co2O3.