Cobalt Nitrate Research Articles

Iron(II)-Catalyzed Synthesis of Nitrated Dihydropyrazole via a Nitrification and C-H Activation/Cyclization Cascade Reaction.

A route for nitrification and C-H activation/cyclization of (E)-N-allyl-N'-benzylidenebenzenesulfonohydrazide and cobalt nitrate via an iron(II)-catalyzed cascade reaction to synthesize nitrated dihydropyrazoles has been developed. The method features convenient operation and good functional group tolerance. In addition, it employs insensitive and inexpensive FeSO4 as the catalyst and provides a direct approach for the preparation of dihydropyrazoles.

Nanoflower-like NiCoFe layered hydroxide by in-situ electrochemical corrosion as highly efficient electrocatalyst for water oxidation

Layered double hydroxides have been widely applied for oxygen evolution reaction (OER) in the alkaline water electrolysis. However, the issues of poor connection between the catalyst and nickel foam and the specific mechanisms for active sites has not been fully documented. In this study, the in-situ nickel foam etching in a mixed solution of ferric chloride and cobalt nitrate at low temperatures was adopted for NiCoFe layered ternary hydroxides (NiCoFe LTHs) synthesis with a better tight integration. Physicochemical characterization indicated that the NiCoFe LTHs could grow directly through corroding nickel foam with a nano-flower-like morphology and structures. That is favorable for electron transfer from the catalytic layer to the conductive substrate. With the transition metal ions interaction and the tight integration construction, NiCo1Fe4-LTH-T60/NF presented an enhanced electrolysis performance with the overpotential of 234 mV (1.464 V vs. RHE) at current density of 100 mA cm−2 in 1 M KOH electrolyte. The Tafel slope for NiCo1Fe4-LTH-T60/NF electrode was 36.19 mV dec−1 for an enhanced OER kinetics. Besides, it demonstrated faster interfacial charge transfer process, better intrinsic electrochemical activity and stability in large current stability testing. It was revealed that the synergistic effect of the transition metal ions interaction enhancement and the mechanism of oxygen evolution elementary reaction for NiCo1Fe4-LTH-T60/NF during the water electrolysis by the electrochemical and theoretical calculation. This work provides theoretical basis and experimental support for the design and synthesis of future OER catalyst and substrate, which is significant for hydrogen and oxygen generation from water electrolysis.

Cobalt(II) catalyzed Michael-type hydroamination of activated olefins

The aza-Michael addition reaction of primary and secondary amines to α,β-unsaturated olefins viz; acrylonitrile, phenyl vinyl sulfone and dimethyl maleate has been carried out using 5–10 mol% Co(NO3)2.6H2O as a catalyst in t-BuOMe at 80–100 °C, giving rise to the desired β-aminocarbonyl compounds or sulfones in moderate to good yields. A wide range of aromatic amines, even those bearing electron withdrawing groups could be added to activated olefins via this strategy. Addition of (hetero)aromatic amines were also feasible, while in case of 2-aminopyridine the reaction was found to be effective only when AgOTf was added along with the catalyst. The aliphatic amines; benzylamine, dibenzylamine, di-n-butylamine were also smoothly added to acrylonitrile and phenyl vinyl sulfone. The methodology describes cobalt(II) nitrate as an eco-friendly, cheap and shelf available catalyst suitable for performing the Michael-type hydroamination reactions.

Investigation of rare earth metal ions (Sm and Er) doped CoMoO4 polymorphs for photocatalytic dye degradation

Cobalt molybdate (CoMoO4) and its rare earth doped variants have emerged as promising photocatalysts for degrading dye pollutants in wastewater. The photocatalysts were prepared using a modified sol-gel method, employing ammonium heptamolybdate tetrahydrate and cobalt (II) nitrate hexahydrate as precursors. The incorporation of samarium and erbium as a dopant was hypothesized to improve the photocatalytic activity of CoMoO4 by altering its band structure and creating defect sites for improved dye adsorption and degradation. The structural and optical properties of the synthesized photocatalysts were characterized using various techniques. The photocatalytic performance of CoMoO4, Sm:CoMoO4 and Er:CoMoO4 was evaluated by monitoring the degradation of MB dye under light irradiation. The results reveal that Sm:CoMoO4 and Er:CoMoO4 catalysts achieve a degradation efficiencies of 99 % and 97 %, respectively, highlighting the potential of rare earth-doped CoMoO4 as an efficient photocatalyst for the remediation of dye contaminated wastewater.

Coordination Compounds of Cobalt(II) Nitrate and Perchlorate with Acetamide and Carbamide: Precursors for the Synthesis of Catalytically Active Tricobalt Tetraoxide

The reactions of cobalt(II) nitrate or perchloride with acetamide (AA) or carbamide (Ur) in an aqueous medium produce coordination compounds [Co(Ur)4](NO3)2 (I), [Co(Ur)6](NO3)2 (II), [Co(AA)4(H2O)2](NO3)2 (III), [Co(AA)4(H2O)2](NO3)2 ∙ 2AA (IV), [Co(Ur)6](ClO4)2, (V), [Co(AA)4(H2O)2](ClO4)2 (VI), and [Co(AA)6](ClO4)2 (VII). The compositions of the isolated complexes are determined by physicochemical methods, and the crystal and molecular structures of compounds II, V, VI, and VII are solved. Specific features of the thermal behavior of all synthesized compounds in a wide temperature range are studied in detail. These compounds are shown to be used as precursors in the preparation of nanosized Co3O4 using self-propagating high-temperature synthesis. The catalytic activity of thus synthesized Co3O4 in the model epoxidation of allyl alcohol is studied.

Facile Fabrication of Co-Doped Porous Carbon from Coal Hydrogasification Semi-Coke for Efficient Microwave Absorption.

A Co-doped porous carbon was successfully fabricated by a facile carbonizing procedure using coal hydrogasification semi-coke (SC) as the carbon and cobalt nitrate as the magnetic precursors, respectively. The mass ratio of the precursors was changed to regulate the microwave absorption (MA) capabilities. The favorable MA capabilities are a result of a synergistic interaction be-tween the dielectric loss from the carbon framework, the magnetic loss from nano-sized Co particles, and multiple scattering from the residual pores. At a thickness of 4.0 mm, the Co/C composite showed the lowest reflection loss of -33.45 dB when the initial mass ratio of cobalt nitrate and SC was 1:1. The effective absorbing bandwidth (EAB) could achieve 3.5 GHz at 2 mm thickness. This work not only opens up a new avenue for the facile fabrication of dielectric and magnetic loss combinations and their structural design, but it also creates a new route for the high value-added exploitation of SC.

An Unprecedented Tridentate-Bridging Coordination Mode of Permanganate Ions: The Synthesis of an Anionic Coordination Polymer-[CoIII(NH3)6]n[(K(κ1-Cl)2(μ2,2',2″-(κ3-O,O',O″-MnO4)2)n∞]-Containing Potassium Central Ion and Chlorido and Permanganato Ligands.

A unique compound (compound 1) with structural features including an unprecedented tridentate-bridging coordination mode of permanganate ions and an eight-coordinated (rhombohedral) κ1-chlorido and tridentate permanganato ligand in a potassium complex containing coordination polymer (CoIII(NH3)6]n[(K(κ1-Cl)2(μ2,2',2″-(κ3-O,O',O″-MnO4)2)n∞) with isolated regular octahedral hexamminecobalt(III) cation was synthesized with a yield of >90%. The structure was found to be stabilized by mono and bifurcated N-H∙∙∙Cl and N-H∙∙∙O (bridging and non-bridging) hydrogen bonds. Detailed spectroscopic (IR, far-IR, and Raman) studies and correlation analysis were performed to assign all vibrational modes. The existence of a resonance Raman effect of compound 1 was also observed. The thermal decomposition products at 500 °C were found to be tetragonal nano-CoMn2O4 spinel with 19-25 nm crystallite size and KCl. The decomposition intermediates formed in toluene at 110 °C showed the presence of a potassium- and chloride-containing intermediates combined into KCl during aqueous leaching, together with the formation of cobalt(II) nitrate hexahydrate. This means that the CoIII-CoII redox reaction and the complete decomposition of the permanganate ions occurred in the first decomposition step, with a partial oxidation of ammonia into nitrate ions.

Green synthesis of ZIF-67 nanoparticles via microfluidics: Towards sustainable nanomaterial production

This study explored the synthesis of zeolitic imidazolate framework-67 (ZIF-67) nanoparticles using a microfluidic reactor, focusing on the effects of reactant concentration, temperature, and flow rate on the material’s properties. Design Expert software was utilized to optimize these variables to enhance the synthesis process while preventing reactor clogging due to precipitate formation. The experiments varied concentrations of cobalt (II) nitrate hexahydrate and 2-methylimidazole, along with temperature and flow rates. After synthesis, the samples underwent extensive characterization, including FTIR, NMR, TEM, SAED, and XRD analyses. FTIR results confirmed the successful formation of ZIF-67, with varying conditions leading to shifts in peak positions and intensities, indicating changes in bonding and molecular structure. NMR spectra provided insights into the hydrogen environments within the nanoparticles. TEM and SAED analyses revealed that the nanoparticles predominantly exhibited a uniform rhombic dodecahedral morphology with diameters ranging from 5 to 10 nm. XRD patterns were consistent with simulated data, showing variations in peak positions and crystallinity with changes in synthesis conditions. The study highlighted that increasing reactant concentrations, temperature, and flow rate generally enhanced the production rate and crystallinity of ZIF-67, with 2-methylimidazole concentration having the most significant impact. The findings contributed to optimizing ZIF-67 synthesis, demonstrating the feasibility of using microfluidic reactors and green solvents for producing high-quality nanoparticles with controlled properties.

Co‐Based Metal–Organic Frameworks With Dual Redox Active Centers for Lithium‐Ion Batteries With High Capacity and Excellent Rate Capability

AbstractSmall molecule organic materials are widely used as anode materials for lithium‐ion batteries (LIBs) due to their high reversible capacity, designable structure, and environmental friendliness. However, they suffer from poor intrinsic electronic conductivity, severe dissolution, and low initial coulombic efficiency. Recently, metal–organic frameworks (MOFs) have demonstrated in metal‐ion batteries, outperforming some small molecule organic materials in terms of both cycling stability and rate capability. Herein, the first rational design and synthesis of a new cobalt‐based MOF (CoBPDCA), are reported employing cobalt(II) nitrate as the metal source and small organic molecules (2,2‐bipyridyl‐4,4‐dicarboxylic acid, BPDCA) as the ligands, which shows exceptional chemical stability and impressive electron conductivity. Most importantly, CoBPDCA electrodes deliver a high reversible capacity of 1112.9 mAh g−1 at 0.05 C (1 C = 1000 mA g−1) and outstanding high‐rate durability (166.3 mAh g−1 after 2500 cycles at 10 C). Employing a series of spectroscopic and morphological characterizations and density functional theory (DFT) calculations, it is revealed that these impressively electrochemical performances are contributed to the dual active redox centers of Co cations and BPDCA ligands (CN and CO groups), and the superb electron conductivity. This work might provide a new strategy and a deeper understanding of the other MOFs' development for LIBs.

Impact of Inverse Manganese Promotion on Silica-Supported Cobalt Catalysts for Long-Chain Hydrocarbons via Fischer–Tropsch Synthesis

One of the challenges in Fischer–Tropsch synthesis (FTS) is the high reduction temperatures, which cause sintering and the formation of silicates. These lead to pore blockages and the coverage of active metals, particularly in conventional catalyst promotion. To address the challenge, this article investigates the effects of the preparation method, specifically the inverse promotion of SiO2-supported Co catalysts with manganese (Mn), and their reduction in H2 for FTS. The catalysts were prepared using stepwise incipient wetness impregnation of a cobalt nitrate precursor into a promoted silica support. The properties of the catalysts were characterized using XRD, XPS, TPR, and BET techniques. The structure–performance relationship of the inversely promoted catalysts in FTS was studied using a fixed-bed reactor to obtain the best performing catalysts for heavy hydrocarbons (C5+). XRD and XPS results indicated that Co3O4 is the dominant cobalt phase in oxidized catalysts. It was found that with increase in Mn loading, the reduction temperature increased in the following sequence 10%Co/SiO2 < 10%Co/0.25%Mn-SiO2 < 10%Co/0.5%Mn-SiO2 < 10%Co/3.0%Mn-SiO2. The catalyst with the lowest Mn loading, 10%Co/0.25%Mn-SiO2, exhibited higher C5+ selectivity, which can be attributed to less MSI and higher reducibility. This catalyst showed the lowest CH4 selectivity possibly due to lower H2 uptake and higher CO chemisorption.

Preparation of Co0.5Cu0.5/CNR catalyst and its performance in hydrogen production by hydrolysis of ammonia borane

Cobalt nitrate and copper nitrate was mixed to prepare solution A. Phenyldicarboxylic acid and N,N-dimethylformamide was mixed to prepare solution B. Co/Cu Lavashield skeleton series materials (Co/Cu-MIL precursors) was then synthesized by mixing the above two solution via solvothermal method. The precursor was further carbonized to produce the MOFs derivatives, i.e. bimetallic carbon nanorods (CoxCu1–x/CNR) catalysts. The morphology and composition of the catalysts were explored by SEM, TEM, XRD, XPS and other characterization means. The results showed that CoxCu1–x/CNR was successfully obtained after calcination of Co/Cu-MIL at high temperature. The activity of the catalyst was optimal when x=0.5, the solvothermal temperature of 120 °C and the calcination temperature of 650 °C. The TOF value of the Co0.5Cu0.5/CNR catalyst for the hydrolysis of ammonia borane for the production of hydrogen was 2718.21 h–1 with activation energy of 51.64 kJ/mol. The catalyst had good cyclic stability. Although the activity decreased, the conversion of AB still maintained 100% after 10 cycles.

Study and characterization of zeolites for the removal of artificial radionuclides in wastewater samples from nuclear power plants

4A, 13X, phillipsite and chabazite zeolites have been characterized regarding their capacity to remove Cs+ and Co2+ ions from aqueous solutions. The aim is to simulate the decontamination process of radioactive wastewater, originating from the former Garigliano nuclear plant in Italy, which is contaminated with 137Cs and 60Co. The four zeolites, in powder state, have been tested with solutions containing cesium nitrate and cobalt nitrate hexahydrate, in both individual and combined configurations, at different solid/liquid ratios. The Cs+ and Co2+ concentrations have been monitored over time by inductively coupled plasma (ICP) spectrometry. The results demonstrate the high efficacy of 13X zeolite providing almost 100 % of removal of both elements in a relatively short time (20–30 min). These findings are the basis for the kinetic characterization of the zeolite using radioactive solutions and, hence, for the setup of an in-situ pre-pilot plant to carry out tests with contaminated wastewater at the Garigliano facility. 13X zeolite presents a promising alternative for decommissioning radioactive wastewater.

One-step hydrothermal fabrication of Co-MOFs/LDH superhydrophobic composite coating with corrosion resistance and wear resistance on anodic aluminum oxide

In recent years, metal–organic framework materials (MOFs) have garnered significant attention in the field of metal corrosion protection. In this study, novel Co-MOFs were synthesized using cobalt nitrate as the metal source and 4,4′-bipyridine as the organic ligand. A one-step solvothermal method was employed to synthesize a black MOFs/LDH composite coating, integrating corrosion resistance, friction reduction, and hydrophobicity into a single coating. The successful reaction between metal ions and organic ligands was confirmed through FTIR, FE-SEM, EDX, XRD, and XPS characterization tests. Cross-sectional SEM and EDX analyses demonstrated the successful synthesis of the coating. Electrochemical tests indicated that after 14 days of immersion in 3.5 wt% NaCl, the composite coating exhibited the lowest corrosion current of 2.23 × 10−9 A∙cm−2, outperforming the aluminum substrate (5.99 × 10−6 A∙cm−2) and anodized aluminum (7.08 × 10−7 A∙cm−2). Hydrophobicity tests showed that without additional modification with low surface energy substances, the composite coating had a contact angle of 154.7°, demonstrating excellent hydrophobicity. Tribological tests revealed that the composite coating exhibited superior tribological performance, with a friction coefficient of 0.3.

Two- and Three-Dimensional Polymeric Co(II) Terephthalates with 3,3',5,5'-Tetrabromo-4,4'-bipyridine (3,3'5,5'-BrBipy)

The reaction of 3,3',5,5'-tetrabromo-4,4'-bipyridine (BrBipy) with cobalt nitrate and terephthalic acid (H2Bdc) gave 2D and 3D metal-organic frameworks {[Co2(Bdc)2(BrBipy)2(H2O)4] · 4DMF} (I) and {[Co2(Ddc)4(BrDipy)] · · 2MeOH} (II), respectively. The structure of the complexes was studied by X-ray diffraction (CCDC nos. 2259216 (I) and 2259214) (II)).

One-step combustion synthesis of high-performance nanosized Co3O4 and Ag-Co3O4 catalysts for propane total oxidation

Devising an effective strategy to refine the physicochemical properties of Co3O4 and tune the Ag-Co interaction is pivotal for developing superior Ag-Co3O4 catalysts targeting VOCs abatement. In this study, nanosized Co3O4 and Ag-Co3O4 (Ag content of 0.5–5.0 wt%) catalysts were prepared via a facile one-pot urea combustion method. The as-prepared catalysts were characterized using various techniques and their performance in propane total oxidation was evaluated. Compared to its counterpart obtained through the direct decomposition of cobalt nitrate, the nanosized Co3O4 exhibited a larger surface area, more oxygen vacancies, better reducibility, and thus superior propane oxidation activity. The addition of Ag can further enhance the catalytic performance by significantly improving the redox properties of Co3O4. The best performance was achieved with the catalyst 3.5 wt% Ag-Co3O4, which mineralized 90 % of propane into CO2 at 200 °C and exhibited excellent cycling stability and long-term durability. In addition, 3.5 wt% Ag-Co3O4 demonstrated high activity under various conditions, including high propane concentration (6000 ppm), high space velocity (160,000 mL g−1h−1), and high water content (10 vol%), making it a promising candidate for practical VOCs removal.

Enhancement of hydrogen evolution activity of CoS2/MoS2 heterostructure catalysts by electronic structure modulation

MoS2 exhibits high catalytic ability; however, its wide band gap (1.73 eV) and poor intrinsic conductivity significantly restrict the enhancement of its catalytic activity. To enhance the electron transfer between the interface of heterojunctions and improve the hydrogen evolution reaction (HER) performance, the paper constructs a CoS2/MoS2 heterostructures by growing CoS2/MoS2-X on carbon cloth (CC) using a straightforward one-step method. It investigates the HER properties of the heterojunctions of various molar ratios of ammonium molybdate to cobalt nitrate. The results indicate that the CoS2/MoS2-X catalyst exhibits excellent electrocatalytic activity (73 mV@10 mA cm−2) and Tafel slope (80.42 mV dec−1) at 1.0 M KOH when the molar ratio of ammonium molybdate to cobalt nitrate is 1:1 (X = 5). CoS2/MoS2-5 exhibits good durability of over 100 h when current densities are 10 and 100 mA cm−2. Density functional theory (DFT) calculations indicate that heterostructures present an optimized Gibbs free energy of hydrogen adsorption (ΔGH*) close to zero, providing insight into the exceptional HER performance. This work provides a simple, effective and innovative strategy for preparing high-activity CoS2/MoS2 catalysts by modulation of electronic structure.

Fabrication of tricobalt tetraoxide thinfilm photocatalyst from cobalt nitrate deposition by a novel spark method

Tricobalt tetraoxide (Co3O4) thinfilm was successfully deposited for the first time by a novel sparking method through a two-step process, which includes cobalt nitrate deposition and subsequent thermal treatment at 300 °C. The formation mechanism of Co3O4 deposition by sparking process from highly pure cobalt wire is elucidated in detail. Deposited Co3O4 thinfilms under different spark repetition rates were intensely characterized and employed as an effective photocatalyst for degradation of organic dye. Notably, the maximum degradation of organic dye was observed for the catalytic thinfilm deposited at low repetition rate owing to its low band gap and porous morphology with smaller size grains, which may lead to the contribution of more charge carriers in the photocatalytic reaction.

THE INFLUENCE OF TEMPERATURE TREATMENT ON THE STRUCTURAL-PHASE COMPOSITION OF SUPPORTED Со-Мо/Al2О3 CATALYTIC SYSTEMS

Using the method of impregnation in an excess of impregnating solution and subsequent temperature treatment in the temperature range of 100-400 °C, the synthesis of γ-modified catalytic systems based on transition metals (Co, Mo) supported on active aluminum oxide was carried out and their physicochemical properties were studied. A distinctive feature of these systems was the use of polyoxometalate complexes (molybdenum blues) obtained by mechanical activation of commercial molybdenum disulfide as a source of molybdenum. The carrier was obtained by high-temperature treatment of industrial pseudoboehmite powder AlOOH (Ishimbay Specialized Chemical Plant of Catalysts LLC). This approach makes it possible to significantly simplify the synthesis of catalytic systems. At the same time, the reagents and technologies used are publicly available and are produced on the territory of the Russian Federation on an industrial scale. The resulting systems are expected to be used in hydrotreating processes (hydrodesulfurization and hydrodenitrogenation) of diesel fractions. The synthesis included the stage of obtaining an impregnating solution by adding a weighed portion of cobalt nitrate to an alcohol solution of molybdenum blue, and the stage of directly impregnating the carrier in an excess of the impregnating solution. After impregnation, the systems were calcined at various temperatures in order to study the genesis of the active components and the effect of temperature treatment on various physicochemical properties. The synthesized systems were studied using various physicochemical methods (XRD, IR spectroscopy). It was found that to completely eliminate the nitro group from the system, a temperature treatment of at least 400 °C is necessary. It was also shown that molybdenum blue can act as a source of Mo. For citation: Zhirov N.А., Akimov Al.S., Sudarev Е.А., Akimov A.S. The influence of temperature treatment on the structural-phase composition of supported Со-Мо/Al2О3 catalytic systems. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 44-49. DOI: 10.6060/ivkkt.20246708.3t.

Boosting mechanical properties of carbon fibers by gas-liquid dual-effect approach

The tensile strength and tensile modulus of existing carbon fibers (CFs) are 3 %–5 % of the theoretical values, which greatly limits the performance of CFs when used alone or as a reinforcing material. To increase the chemical reaction activity and roughness of the surface of CFs based on the enhancement of their mechanical properties, a comprehensive treatment of CFs was carried out by the gas-liquid dual-effect method. CFs were oxidized at high temperatures after immersion treatment using cobalt nitrate solution, and the effects of cobalt nitrate solution concentration, oxidation time, and calcination temperature on the surface morphology, functional groups, structural defects, and mechanical properties of CFs were investigated by the controlled-variable method. The results showed that when the concentration of cobalt nitrate solution was 0.2 molL-1, the calcination temperature was 200 °C, and the oxidation time was 4 h, the modification effect was the best. At this time, the tensile strength of CF is 6104.50 MPa, which is 40.35 % higher than that of the pure CF, and the tensile modulus is 378.56 GPa, which is 13.27 % higher than that of the pure CF, with a significant enhancement effect. It can offer feasible ideas for further research and development of CF composites, and provide an effective way to promote the industrialization of modified CFs for application.

Mechanically Mixed Thermally Expanded Graphite/Cobalt(II) Perrhenate—Co(ReO4)2—As Electrodes in Hybrid Symmetric Supercapacitors

A mechanically homogenized composite of expanded graphite and cobalt(II) perrhenate has been described. Cobalt(II) perrhenate was obtained in a reaction of perrhenic acid with cobalt(II) nitrate. A simple mortar homogenization method was used to enhance the intercalation of cobalt species within the carbon matrix. The specific capacitance of the composite was enhanced by 50% (to 78 F/g) in comparison to bare expanded graphite (52 F/g). The electrochemical characteristics were significantly improved, including better cyclability (7% capacitance loss), a lower resistance of the electrode material, and a lower iR drop, with respect to expanded graphite without cobalt(II) perrhenate active species. Expanded graphite, with its unique specific surface area and pore size diameter, was proved to be a potential and cheap carbon support.