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This study investigates the potential of cerium (Ce) doping to improve the performance of cobalt oxide (Co₃O₄) nanoparticles as battery-type supercapacitor electrodes. Pure Co₃O₄ nanoparticles were synthesized via a solution combustion method and then doped with 2.5 % (Ce-Co 3 O 4) and 5 % Ce (CeO 2 -Co 3 O 4). Comprehensive characterization, including X-ray diffraction (XRD), Raman spectroscopy, and field emission scanning electron microscopy (FESEM), was used to analyze the impact of Ce doping on the material properties. XRD analysis confirmed the successful incorporation of Ce into the Co₃O₄ structure, with distinct CeO 2 phases forming at higher doping levels. Ce doping resulted in decreased crystallite size and peak intensity, indicating reduced crystallinity and increased defect concentration. Raman spectroscopy corroborated these findings, showing a redshift that suggests weakened metal-oxygen bonds and smaller grain sizes due to Ce³⁺ incorporation. FESEM images demonstrated that Ce doping effectively reduced nanoparticle agglomeration, with 2.5 % doping leading to smaller particles and 5 % doping promoting a 2D flake-like morphology with increased porosity. Nitrogen adsorption-desorption measurements revealed a significant increase in surface area and pore volume for CeO 2 -Co₃O₄, facilitating improved electrolyte diffusion and reduced resistance, thereby enhancing electrochemical performance. Evaluation of the electrochemical properties of undoped and Ce-doped Co₃O₄ materials revealed a battery-like response in a three-electrode configuration. Notably, the CeO 2 -Co 3 O 4 exhibited a superior specific capacity of 603.3 C g−1 at a current density of 1 A g−1, significantly exceeding the values of 368.5 C g−1 and 127.1 C g−1 achieved by Ce-Co 3 O 4 and undoped Co 3 O 4 , respectively. Furthermore, the CeO 2 -doped Co 3 O 4 demonstrated exceptional cyclic stability, retaining 87 % of its initial capacity after undergoing 5000 charge-discharge cycles at a high current density of 10 A g−1. These results suggest that Ce doping is a promising strategy for optimizing Co₃O₄-based battery-type electrode materials, potentially leading to the development of high-performance and cost-effective energy storage systems. [ABSTRACT FROM AUTHOR]

This study introduces CTAB-loaded Co₃O₄ nanoparticles (NPs) as a highly efficient solution for removing Brilliant Yellow (BY), Reactive Yellow (RY) and Methyl Orange (MO) dye from contaminated water. Synthesized via a co-precipitation and hydrothermal method, these NPs were characterized using UV-Vis, FTIR, XRD, TEM, and SEM. The Co₃O₄ NPs, with a crystallite size of 11.88 nm and an average particle size of 13 nm, achieved 100% photocatalytic degradation of BY dye (120 mg/L) within 140 min. Additionally, the NPs demonstrated promising photocatalytic activity against RY and MO dyes. The synergy between CTAB and Co₃O₄ NPs enhances dye degradation, positioning them as a cost-effective and efficient solution for wastewater treatment. This work highlights the environmental potential of CTAB/Co₃O₄ NPs in addressing water pollution challenges. [ABSTRACT FROM AUTHOR]

There is a rising interest in nanocomposites with unanticipated features that are different from traditional materials to fulfill the demands of these applications. Cobalt oxide (Co3O4) nanoparticles, and cobalt oxide with multi-walled carbon nanotubes (Co3O4/ MWCNTs) as nanocomposites were created. In this study, cobalt oxide nanoparticles (Co3O4 NPs) were synthesized via co-precipitation method chemical using CoCl2 salt as a source of cobalt nanoparticles and sodium hydroxide solution as a factor agent at room temperature. The cobalt hydroxide (Co(OH)2) precipitate was obtained, then it calcinated the cobalt hydroxide precipitate at 600°C to obtain the cobalt oxides nanoparticles (Co3O4 NPs). Also, MWCNTs were prepared by a locally manufactured reactor at 423 k. Binary composites were prepared by solution method using cobalt oxide nanoparticles dispersion over MWCNTs surfaces. The structural, morphological, and spectral properties were confirmed and investigated by using FE-SEM, Raman spectroscopy, and (XRD), respectively. The surface area and pore size obtained by BET and BJH showed that the binary nanocomposites (Co3O4/MWCNTs) have a higher surface area than their pristine cobalt oxide and multi-walled carbon nanotubes nanoparticles. The adsorption processes of nanocomposites have attracted significant care from the scientific public because of their distinctive possessions and aptitude to reduce and adsorb Cu+2 and Ni+2 as heavy metals from water pollution. As a result, Co3O4 and its nanocomposite with MWCNTs were used to remove copper and nickel ions from the dilute aqueous solution.

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In this study, Co3O4 nanoparticles were used as nanocatalyst for two different series of nitrogen-containing heterocyclic compounds, including pyrrole (Pyo) derivatives and pyrano [2, 3-c]pyrazole (Pya[2, 3-c]Pyz) derivatives. In the synthesis of derivatives, using 15 mol% and 10 mol% of the catalyst for Pyo derivatives and Pya[2, 3-c]Pyz derivatives, respectively, an efficiency between 83% and 96%, were observed. In addition, novel derivatives of Pyo and Pya[2,3- c]Pyz were synthesized and their structures were confirmed. In general, the advantages of using cobalt nanoparticles compared to previous reports include the synthesis of new derivatives, lower temperature used in the synthesis of derivatives, shorter synthesis time and high efficiency. The biological properties of the synthesized products, such as antibacterial, antifungal, and antioxidant properties, were tested and investigated. In antibacterial and antifungal tests, IZD, MIC, MBC, and MFC were measured and reported. In antioxidant activity, IC50 was calculated and reported. High reusability, green and environmentally friendly, synthesis of new derivatives and synthesis of products with higher efficiency and shorter time were the important benefits of using cobalt nanoparticles as a catalyst. In antioxidant tests, the IC50 for synthesized Pyo derivatives and Pya[2, 3-c] Pyz derivatives were between 12.2 and 13.71 μg/mL, and 16.18--17.75 μg/mL, respectively. In antimicrobial testes, the MIC for synthesized Pyo derivatives and Pya[2, 3-c]Pyz derivatives were between 2 and 4,096 μg/mL, and 2--2048 μg/mL, respectively. The results showed that the antioxidant property of Pyo derivatives were more than Pya[2, 3-c] Pyz derivatives, but the antimicrobial effect of Pya[2,3-c] Pyz derivatives were more than Pyo derivatives. The antioxidant results proved that the activity of Pyo derivatives and Pya[2, 3-c] Pyz derivatives does not depend on the substitutions of the derivatives and is close to each other. Therefore, based on this, a proposed mechanism for stability of DPPH by Pyo derivatives and Pya[2, 3-c] Pyz derivatives were suggested. Finally, based on the more stable resonance structures of Pyo derivatives, compared to Pya[2, 3-c] Pyz derivatives, its high antioxidant property was justified. Pya[2, 3-c] Pyz derivatives has two heterocyclic rings connected together pyrano and pyrazole, but Pyo derivatives has only one heterocyclic ring (pyrrole). So high antimicrobial property of Pya[2, 3-c] Pyz derivatives compared to Pyo derivatives can be attributed to having two bioactive heterocyclic rings. [ABSTRACT FROM AUTHOR]

The present study explores the influence of Cobalt oxide nanoparticles(Co3O4 NPs) on the physicochemical characteristics of Poly(vinylalcohol)/ Chitosan (PVA/Cs) blend. Using a variety of techniques, the pure blend and the nanocomposites' composition, structure, optical, thermal, and mechanical properties, and antibacterial activity were characterized. The Co3O4 NPs were produced by precipitation method utilizing cobalt salt as the raw material. The crystalline nature of the nanoparticles and semi-crystalline behavior of the PVA/Cs are demonstrated by the XRD data. Adding nanoparticles to the pure blend reduced the intensity of the semi-crystalline. The rise in absorption intensity observed in UV-visible spectra upon the incorporation of Co3O4 NPs into the PVA/Cs blend indicates an improved dispersion of the nanoparticles within the blend. When Co3O4 NPs are added, the energy band-gap Egdir and Egind of PVA/Cs–Co3O4 samples greatly decrease. According to TGA data, the thermal stability of nanocomposites was significantly higher than that of the PVA/Cs blend, and it rose as the concentration of nanoparticles increased. When compared to neat PVA/Cs film, mechanical property investigation of PVA/Cs–Co3O4 nanocomposites films revealed enhanced features. The effectiveness of the PVA/Cs–Co3O4 nanocomposite films in inhibiting the growth of microorganisms was assessed by evaluating their antimicrobial activity (ANMAC) against a range of bacteria and fungi. The inclusion of Co3O4 NPs led to an increase in activity against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria as well as fungi Candida albicans and Aspergillus niger (C. albicans and A. niger). The addition of Co3O4 NPs to the PVA/Cs blend effectively improved the material's optical, thermal, mechanical, and antibacterial properties. This remarkable improvement stems from the Co3O4 NPs, which were introduced into the PVA/Cs blend in different amounts, leading to the development of novel nanocomposites. The outstanding properties of Co3O4/PVA/Cs nanocomposite films suggest their potential for applications in optoelectronics and food packaging. [ABSTRACT FROM AUTHOR]

Spinel Co3O4 nanoparticles smaller than 10 nm were effectively produced in this study using a Co-precipitation method under optimal conditions. The as-synthesized Co3O4 nanoparticles were found to have great purity and a cubic Co3O4 phase structure with good crystallinity and crystallite size of approximately 9.3 nm, as determined by X-ray diffraction investigation. The Transmission Electron Microscope and Scanning Electron Microscope definitively verified the spherical nanoparticle structure with high density and consistent orientations. The high-resolution-TEM investigation revealed that the produced spinel Co3O4 nanoparticles are single-crystalline and free from observable imperfections. The HR-TEM results indicated that Co3O4 nanoparticles exhibit distinct lattice fringes that correspond to the interplanar spacings identified in the XRD investigation. The energy-dispersive X-ray spectroscopy investigation definitively verified the high purity and stoichiometric production of the nanoparticles. The FT-IR spectra of Co3O4 nanoparticles showed absorption peaks at v1 = 540 cm−1 and v2 = 656 cm−1, confirming the spinel phase structure of the nanoparticles. UV–Vis spectroscopy was utilized to confirm the existence of two distinct band gaps in Co3O4 nanoparticles at energy levels of 3.4 eV and 4.21 eV. Obtaining Co3O4 nanoparticles smaller than 10 nm with specific properties allows for the development of innovative and effective optoelectronic devices with customized features. [ABSTRACT FROM AUTHOR]

In the present investigation, pure and different concentrations (2%, 4%, 6%, 10%) of Ag-doped Co3O4 nanoparticles have been synthesized by the sonochemical method and subsequent calcination at different high temperatures. Structural, optical, morphological properties and elemental composition of synthesized nanoparticles have been characterized using X-ray diffraction, UV–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. According to X-ray diffraction results, no peaks related to silver or silver oxide were observed in the diffractograms of doped samples. Blue shift was observed in the absorption curve of Ag-doped Co3O4 nanoparticles compared to undoped Co3O4 nanoparticles. From transmission electron microscopy measurements, 2%, 4% and 6% Ag-doped Co3O4 nanoparticles thermal annealed at 500 °C exhibit sphere-like and irregularly structured morphology, while 10% Ag-doped Co3O4 nanoparticles have a rhombohedral-like, hexagonal and spherical morphology. The dielectric constant value (ɛʹ) was found to decrease with increasing frequency and it can be explained by Maxwell–Wagner model. The value of the dielectric constant increased with increasing of temperature from 25 to 100 °C and the highest value was observed for Ag0.1Co2.9O4/PVA sample at 100 °C temperature. [ABSTRACT FROM AUTHOR]

To investigate a highly active catalyst for CER and explore low concentrations of Cl− electrocatalytic product Cl2, Co3O4/GF catalysts were constructed by a methanesulfonic acid system plating and calcination process. SEM shows Co3O4/GF-0.1 has a uniform distribution of nanoparticles. TEM, XRD, and XPS results confirmed the formation of Co3O4. The catalytic activity in high concentrations of Cl− and low concentrations of Cl− are discussed. LSV suggests Co3O4/GF-0.1 with an initial potential of 1.06 V, The overpotential at a current density of 10 mA cm−2 is 232 m V, Tafel slope 109.26 mV dec−1, the CER reaction order is 0.54 at 1, 2 and 3 M NaCl, and 0.18 at 4, 5 and 6 M NaCl, too high concentration of Cl− slow down control of speed. In low concentration solution, the CER reaction order is 0.99, which can achieve the degradation rate of 90.8% in 50 ppm ammonia nitrogen. The apparent constant and the concentration of Cl− conform to the equation K = 1.44 × 10–3 C00.95. From low concentration to high concentration, energy consumption decreased, and Faraday efficiency increased. Electrode with jECSA = 0.52 mA cm−2, 3D structure GF has a large specific active area that promotes the diffusion of Cl−. This work provides analysis methods and ideas for the preparation of the high activity and stability CER catalyst at low Cl− concentrations in the actual water body. [ABSTRACT FROM AUTHOR]

The hydrothermal method has been utilized to synthesize graphitic carbon nitride (g-C3N4) polymers and cobalt oxide composites effectively. The weight percentage of g-C3N4 nanoparticles influenced the electrochemical performance of the Co3O4-g-C3N4 composite. In an aqueous electrolyte, the Co3O4-g-C3N4 composite electrode, produced with 150 mg of g-C3N4 nanoparticles, revealed remarkable electrochemical performance. With an increase in the weight percentage of g-C3N4 nanoparticles, the capacitive contribution of the Co3O4-g-C3N4 composite electrode increased. The Co3O4-g-C3N4-150 mg composite electrode shows a specific capacitance of 198 F/g. The optimized electrode, activated carbon, and polyvinyl alcohol gel with potassium hydroxide were used to develop an asymmetric supercapacitor. At a current density of 5 mA/cm2, the asymmetric supercapacitor demonstrated exceptional energy storage capacity with remarkable energy density and power density. The device retained great capacity over 6k galvanostatic charge–discharge (GCD) cycles, with no rise in series resistance following cyclic stability. The columbic efficiency of the asymmetric supercapacitor was likewise high. [ABSTRACT FROM AUTHOR]

In this study, we report on the preparation and characterization of Co 3 O 4 nanoparticles (NPs) embedded in polyaniline-Camphor Sulfonic Acid (PANI-CSA) polymer matrix via electrochemical polymerization method. Developing conductive organic films with tunable optical properties are crucial for many novel optoelectronic applications. Thus, incorporation of metallic oxide nanoparticles (Co 3 O 4 NPs) into polymer matrix (PANI-CSA) represents an alternative approach to address these desired features. As a result of careful optimization of several growth conditions, PANI-CSA/Co 3 O 4 hybrid nanocomposites with high crystalline and homogeneous structures were successfully synthesized on ITO substrates. The impact of Co 3 O 4 NPs concentrations on the structural and optical properties has been extensively investigated. A variety of structural and optical techniques, including FTIR, UV-VIS spectroscopy, and XRD, were employed to characterize the prepared hybrid nanocomposites. The initial findings and analysis reveal that the integration of Co 3 O 4 NPs into PANI-CSA matrix have a trifunctional role in reducing π-polaron and Urbach energies (E U) whereas increasing π-π* band gaps. A further increase in NPs concentration up to 12 wt % results in continuous increase in the absorbance bands and absorption coefficients, indicating improved optical properties as compared to the control sample (PANI-CSA without NPs). The observed redshifts in absorbance band positions are attributed to narrowing of the optical band gap caused by interactions between PANI-CSA chains and Co 3 O 4 NPs. FTIR spectra confirmed the exact chemical composition of PANI-CSA/Co 3 O 4 nanocomposites, exhibiting broadened and less intense peaks compared to the control sample, indicating their interaction at the molecular levels. Additionally, XRD measurements indicate that no peaks of other phases were detected in all nanocomposites, demonstrating their purity and crystallinity. Finally, A single oscillator model by Wemple-DiDomenico (WDD) coupled with a Sellmeier dispersion relation based on one term has been utilized to model the typical electronic transition excitation energies, dispersion energies, optical conductivities, and many other optical desperation parameters for PANI-CSA and PANI-CSA/Co 3 O 4 at various concentrations. For instance, in response to increased NPs content, linear optical susceptibility, third-order nonlinear optical susceptibility, and nonlinear refractive index decrease. In contrast, the ratio of free carriers to effective mass (N/m) increased from 4.73 × 1039 to 4.91 × 1039 m−3 kg−1 with increasing NPs concentration. Based on the observed results, these hybrid nanocomposites possess improved properties, indicating their potential use as active materials in a variety of novel optoelectronic applications. [ABSTRACT FROM AUTHOR]

Developing high‐performance anode current collectors with three‐dimensional structure and lithiophilic layers is of great importance to further advance the application of lithium metal batteries. However, relatively few research has focused on the transition of substrate and the intrinsic structure stability after electrodeposition of lithium on substrates, which leads to an incomplete understanding of the behavior of lithium deposition. Herein, a lithium metal anodes host with a highly stable and 3D structure has been effectively produced through in situ development of nanoflake arrays embedded with Co3O4 obtained from ZIF on nickel foams (Co3O4‐NF). And the actual lithium deposition sites and lithium deposition process on Co3O4‐NF are elucidated via a combination of characterization techniques and electrochemical analytical methods. Consequently, the resulting Co3O4‐NF@Li anodes could effectively inhibit lithium dendrite formation and mitigate volume expansion, demonstrating a significantly extended and consistent lifespan of 800 cycles (1600 h) at 1 mA cm−2 with low overpotential and insignificant voltage fluctuation for the process of lithium stripping and plating in symmetric cells. Herein, it is aimed to examine the transitions of metal oxides as a lithiophilic site for the lithium metal anode. It offers novel perspectives and approaches for the design of dendrite‐free lithium metal anodes. [ABSTRACT FROM AUTHOR]

D-penicillamine (D-PA) is a sulfur-containing drug that has been used for various health conditions. However, like any medication, overdosing on D-PA can have adverse effects and may require additional treatment. Therefore, developing simple and sensitive methods for sensing D-PA can play a crucial role in improving its efficacy and reducing its side effects. Sensing technologies, such as electrochemical sensors, can enable accurate and real-time measurement of D-PA concentrations. In this work, we developed a novel electrochemical sensor for detecting D-PA by modifying a carbon paste electrode (CPE) with a multi-walled carbon nanotube-Co3O4 nanocomposite, benzoyl-ferrocene (BF), and ionic liquid (IL) (MWCNT-Co3O4/BF/ILCPE). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA) were employed to explore the electrochemical response of D-PA on the developed sensor, the results of which verified a commendable electrochemical performance towards D-PA. Under optimized conditions, the developed sensor demonstrated a rapid response to D-PA with a linear dynamic range of 0.05 μM–100.0 μM, a low detection limit of 0.015 μM, and a considerable sensitivity of 0.179 μA μM−1. Also, the repeatability, stability, and reproducibility of the MWCNT-Co3O4/BF/ILCPE sensor were studied and showed good characteristics. In addition, the detection of D-PA in pharmaceutical and biological matrices yielded satisfactory recoveries and relative standard deviation (RSD) values. [ABSTRACT FROM AUTHOR]

In this study, Co3O4 nanoparticles were used as nanocatalyst for two different series of nitrogen-containing heterocyclic compounds, including pyrrole (Pyo) derivatives and pyrano [2, 3-c]pyrazole (Pya[2, 3-c]Pyz) derivatives. In the synthesis of derivatives, using 15 mol% and 10 mol% of the catalyst for Pyo derivatives and Pya[2, 3-c]Pyz derivatives, respectively, an efficiency between 83% and 96%, were observed. In addition, novel derivatives of Pyo and Pya[2,3-c]Pyz were synthesized and their structures were confirmed. In general, the advantages of using cobalt nanoparticles compared to previous reports include the synthesis of new derivatives, lower temperature used in the synthesis of derivatives, shorter synthesis time and high efficiency. The biological properties of the synthesized products, such as antibacterial, antifungal, and antioxidant properties, were tested and investigated. In antibacterial and antifungal tests, IZD, MIC, MBC, and MFC were measured and reported. In antioxidant activity, IC50 was calculated and reported. High reusability, green and environmentally friendly, synthesis of new derivatives and synthesis of products with higher efficiency and shorter time were the important benefits of using cobalt nanoparticles as a catalyst. In antioxidant tests, the IC50 for synthesized Pyo derivatives and Pya[2, 3-c] Pyz derivatives were between 12.2 and 13.71 μg/mL, and 16.18–17.75 μg/mL, respectively. In antimicrobial testes, the MIC for synthesized Pyo derivatives and Pya[2, 3-c]Pyz derivatives were between 2 and 4,096 μg/mL, and 2–2048 μg/mL, respectively. The results showed that the antioxidant property of Pyo derivatives were more than Pya[2, 3-c] Pyz derivatives, but the antimicrobial effect of Pya[2,3-c] Pyz derivatives were more than Pyo derivatives. The antioxidant results proved that the activity of Pyo derivatives and Pya[2, 3-c] Pyz derivatives does not depend on the substitutions of the derivatives and is close to each other. Therefore, based on this, a proposed mechanism for stability of DPPH by Pyo derivatives and Pya[2, 3-c] Pyz derivatives were suggested. Finally, based on the more stable resonance structures of Pyo derivatives, compared to Pya[2, 3-c] Pyz derivatives, its high antioxidant property was justified. Pya[2, 3-c] Pyz derivatives has two heterocyclic rings connected together pyrano and pyrazole, but Pyo derivatives has only one heterocyclic ring (pyrrole). So high antimicrobial property of Pya[2, 3-c] Pyz derivatives compared to Pyo derivatives can be attributed to having two bioactive heterocyclic rings.

Developing high‐performance anode current collectors with three‐dimensional structure and lithiophilic layers is of great importance to further advance the application of lithium metal batteries. However, relatively few research has focused on the transition of substrate and the intrinsic structure stability after electrodeposition of lithium on substrates, which leads to an incomplete understanding of the behavior of lithium deposition. Herein, a lithium metal anodes host with a highly stable and 3D structure has been effectively produced through in situ development of nanoflake arrays embedded with Co3O4 obtained from ZIF on nickel foams (Co3O4‐NF). And the actual lithium deposition sites and lithium deposition process on Co3O4‐NF are elucidated via a combination of characterization techniques and electrochemical analytical methods. Consequently, the resulting Co3O4‐NF@Li anodes could effectively inhibit lithium dendrite formation and mitigate volume expansion, demonstrating a significantly extended and consistent lifespan of 800 cycles (1600 h) at 1 mA cm−2 with low overpotential and insignificant voltage fluctuation for the process of lithium stripping and plating in symmetric cells. Herein, it is aimed to examine the transitions of metal oxides as a lithiophilic site for the lithium metal anode. It offers novel perspectives and approaches for the design of dendrite‐free lithium metal anodes.

An electrochemical sensor for anti-inflammatory drug flufenamic acid, based on cobalt oxide (Co3O4) modified carbon paste electrode (CPE), has been fabricated. Co3O4 NPs was synthesized and characterized by UV-visible spectrophotometry, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The novel 0.5%(w/w)Co3O4/CPE sensor was also evauatedusing the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It showed a much-enhanced electroactive surface area and low charge transfer resistance (Rct), revealing that it has greatly enhance electron transfer process. Square wave voltammetry (SWV) was utilized as a sensitive method for the determination of very low concentrations of flufenamic acid. Under the optimized conditions, the limits of detection (LOD) and quantification (LOQ) of 0.5%Co3O4(w/w)/CPE were 4.8×10–9 M (1.35 ng/mL) and 1.6×10–8 M (4.50 ng/mL), respectively. After validation of the fabricated sensor, it was successfully applied for sensitive and selective determination of the drug in spiked human serum with LOD and LOQ of 4.5×10–8 M (12.65 ng/mL) and 1.5×10–7 M (42.18 ng/mL). [ABSTRACT FROM AUTHOR]

[Display omitted] The sluggish reaction kinetics and unfavorable shuttling effect are regarded as obstacles to the practical application of lithium-sulfur (Li-S) batteries. To resolve these inherent drawbacks, we synthesized novel multifunctional Co 3 O 4 @NHCP/CNT as the cathode materials consisting of carbon nanotubes (CNTs)-grafted N -doped hollow carbon polyhedrons (NHCP) embedded with cobalt (II, III) oxide (Co 3 O 4) nanoparticles. The results indicate that the NHCP and interconnected CNTs could provide favorable channels for electron/ion transport and physically restrict the diffusion of lithium polysulfides (LiPSs). Furthermore, N doping and in-situ Co 3 O 4 embedding could endow the carbon matrix with strong chemisorption and effective electrocatalytic activity toward LiPSs, thus prominently promoting the sulfur redox reaction. Benefiting from these synergistic effects, the Co 3 O 4 @NHCP/CNT electrode exhibits a high initial capacity of 1322.1 mAh/g at 0.1 C, and a capacity retention of 710.4 mAh/g after 500 cycles at 1 C. Impressively, even at a relatively high current density of 4 C, the Co 3 O 4 @NHCP/CNT electrode achieves a high capacity of 653.4 mAh/g and outstanding long-term cycle stability for 1000 cycles with a low decay rate of 0.035% per cycle. Hence, the design of N -doped CNTs-grafted hollow carbon polyhedrons coupled with transition metal oxides would provide effective promising perspective for developing high-performance Li-S batteries. [ABSTRACT FROM AUTHOR]

Three types of Co3O4 catalyst, namely Co3O4 nanoparticles (denoted as Co3O4-NPs, ∼12 nm in diameter), Co3O4 nanoparticles encapsulated in mesoporou s SiO2 (denoted as Co3O4@SiO2), and Co3O4 nanoparticles inside microporous SiO2 hollow sub-microspheres (denoted as Co3O4-in-SiO2), were explored to catalyze the combustion of lean methane. It was found that the methane conversion over the three catalysts has the order of Co3O4-NPs ≈ Co3O4@SiO2 > Co3O4-in-SiO2 due to the different catalyst structure. The comparison experiments at high temperatures indicate the Co3O4@SiO2 has a significantly improved anti-sintering performance. Combined with the TEM and BET measurements, the results prove that the presence of the mesoporous SiO2 layer can maintain the catalytical activity and significantly improve the anti-sintering performance of Co3O4@SiO2. In contrast, the microporous SiO2 layer reduces the catalytical activity of Co3O4-in-SiO2 possibly due to its less effective diffusion path of combustion product. Thus, the paper demonstrates the pore size of SiO2 layer and catalyst structure are both crucial for the catalytical activity and stability.

The design of hybrid electrocatalysts with abundant active sites and long term stability is crucial for efficient oxygen evolution reaction (OER) application. Cobalt oxide is considered as one of the most promising electrocatalysts to replace noble metal due to its low cost, availability, and electrocatalytic activity towards the oxygen evolution reaction in alkaline media. However, nano-scale cobalt oxide suffers from severe surface self-agglomeration during the OER process, so that leading to poor activity and durability. Herein, ultra-small cobalt oxide nanoparticles are anchored on the surface of nitrogen doped porous 3D graphitic carbon nano-spheres (N-ACS@Co 3 O 4) to increase the amount of exposed active site and avoid the self-agglomeration. The obtained electrocatalyst (N-ACS@Co 3 O 4) is enriched with abundant oxygen vacancies and exhibits a superior OER activity (Overpotential of 237 mV at 10 mA.cm−2) and exceptional stability for at least 30 h in alkaline electrolyte (1 M KOH). The DFT calculations demonstrate that the strong adsorption of Co 3 O 4 on N-doped graphene can prevent its agglomeration, and therefore improves the stability of Co 3 O 4 nanoparticles during OER process in line with the experimental results. • Cobalt oxide nanoparticles are synthesized on the surface of nitrogen doped carbon. • The hybrid composite enhances the conductivity, charge transfer and generate additional defect active sites. • The N-ACS@Co 3 O 4 exhibits a superior OER activity and exceptional long-term durability. • DFT calculations demonstrate a strong adsorption of Co 3 O 4 on N-doped graphene. • The strong adsorption of Co 3 O 4 prevents its agglomeration, and improves the stability. [ABSTRACT FROM AUTHOR]

Lithium batteries, as a type of advanced battery technology, have extremely high application value. However, lithium-ion batteries are prone to aging and malfunction after prolonged charging and discharging, which affects their performance. The correct selection of electrode materials can improve the service life of lithium-ion batteries. In order to optimize the electrochemical materials of lithium-ion batteries, this study conducted electrochemical analysis on graphene oxide (GO) and Co3O4 (GO/Co3O4) nanocomposites used as anodes of longacting lithium-ion batteries. The GO/Co3O4 nanocomposites were synthesized by using hydrothermal method, and the properties of GO/Co3O4 nanocomposites were analyzed. X-ray diffraction (XRD) analysis showed that Co3O4 nanoparticles were uniformly formed on the surface of GO nanosheets. The GO/Co3O4 nanocomposite electrode had 50% by weight (wt) of Co3O4 according to electrochemical characterizations of the GO, Co3O4, and GO/Co3O4 electrodes in lithium-ion batteries. The capacity was found to increase when the Co3O4 content was increased to 50% of the sample, while the capacity decreased as Co3O4 concentration increased. The GO/Co3O4 nanocomposite electrode that contained 50 wt% Co3O4 exhibited excellent cyclic stability, delivering more than 1,115 mA h/g at a current density of 0.1 A/g with minimal capacity loss, a Coulombic efficiency that approached almost 99.5% over 500 cycles, and good capacity retention (95%). Therefore, GO/Co3O4 nanocomposite could be an appropriate electrode material with improved cycling stability. The results of this study provided a good direction for the optimization of electrode materials and electrochemical research in lithium batteries. [ABSTRACT FROM AUTHOR]

The connection between the active components and supports in a catalyst is important for the high activity and long‐term stability during catalysis. Here, Co3O4 nanoparticles embedded in F, N‐doped graphene (Co3O4/F, N‐doped G) are synthesized by silicon‐hydrogen bond reduction. F and N atoms doped graphene interacts with Co3O4 nanoparticles to optimize oxygen reduction reaction (ORR) catalytic activity. The optimal Co3O4/F, N‐doped G‐2 catalyst with Co loading of 3.38 wt% shows a half‐wave potential of 0.852 V vs RHE in 0.1 M KOH solution. Furthermore, Co3O4/F, N‐doped G‐2 catalyst outputs an extremely high open circuit voltage of 1.47 V and an excellent power density of 280 mW cm−2 at current density of 450 mA cm−2 when applied to the primary Zn‐air batteries. Due to the synergetic effects from Co3O4 and supports (F, N‐doped G), Co3O4/F, N‐doped G‐2 catalyst also shows excellent stability and anti‐toxicity, and has good practical application prospects. [ABSTRACT FROM AUTHOR]

In this paper, we report a successful one-step synthesis of Co3O4 Nanoparticles/Laser induced graphene (NPs/LIG) composite by using 1064 nm laser with irradiating cobalt salts impregnated basswood slices in air. The prepared Co3O4 NPs/LIG composites show uniformly distributed nanoparticles on the high-quality 3D graphene. It can be directly used as working electrode for electrochemical reactions without the need for extra post-treatment and exhibits remarkable performance for electrocatalytic OER reaction with an overvoltage of 325 mV at current density of 10 mA·cm−2 and Tafel slope of 66.63 mV·dec−1. Due to its great capability of fabrication precision, simplicity and high speed, this technique indicates immense potential in large scale electrochemical micro-sensor manufacture.

The hydrothermal method has been utilized to synthesize graphitic carbon nitride (g-C3N4) polymers and cobalt oxide composites effectively. The weight percentage of g-C3N4 nanoparticles influenced the electrochemical performance of the Co3O4-g-C3N4 composite. In an aqueous electrolyte, the Co3O4-g-C3N4 composite electrode, produced with 150 mg of g-C3N4 nanoparticles, revealed remarkable electrochemical performance. With an increase in the weight percentage of g-C3N4 nanoparticles, the capacitive contribution of the Co3O4-g-C3N4 composite electrode increased. The Co3O4-g-C3N4-150 mg composite electrode shows a specific capacitance of 198 F/g. The optimized electrode, activated carbon, and polyvinyl alcohol gel with potassium hydroxide were used to develop an asymmetric supercapacitor. At a current density of 5 mA/cm2, the asymmetric supercapacitor demonstrated exceptional energy storage capacity with remarkable energy density and power density. The device retained great capacity over 6k galvanostatic charge–discharge (GCD) cycles, with no rise in series resistance following cyclic stability. The columbic efficiency of the asymmetric supercapacitor was likewise high.

Numerous researches have been directed toward enzyme-free biosensors to alleviate the shortcomings encountered with enzymatic biosensors, in particular the intricate enzyme immobilization procedure. Herein, Co3O4/electrospun carbon nanofiber (ECNF) nanocomposites are successfully prepared to be employed as enzyme-free biosensors for diagnosis of glucose. Two parameters including the carbonization time and the amount of Cobalt(ii) acetate tetrahydrate precursor are optimized, which are 5 h and 0.5 g, respectively. The 0.5 Co3O4/ECNF-5 h nanocomposite delivers superior sensitivity (475.72 μA·mM−1·cm−2), broad linear range (2–10 mM), and detection limit (LOD) less than 1 mM (0.82 Mm). In addition, the electrode shows excellent selectivity. The chronoamperometric analysis of 0.5 Co3O4/ECNF-5 h nanocomposite is performed by adding successively glucose analyte and interfering agents to the 0.1 M sodium hydroxide solution. No significant amperometric signal to the interfering agents including uric acid, ascorbic acid, and dopamine is delivered by this electrode, testifying the great selectivity of the electrode toward the diagnosis of target analyte (glucose) in spite of the existence of interfering species. Taking the aforementioned explanations into account, it can be concluded that the Co3O4/ECNF nanocomposite can be an appropriate free-stand electrode for high-performance enzyme-free glucose biosensor.

Senna auriculata flower extract was utilized in this study for the bio generation of cobalt oxide (Co 3 O 4) nanoparticles. Powder X-ray diffraction (XRD), Fourier Transformed Infrared spectra (FTIR), UV–Visible spectroscopic analysis, and field-emission scanning electron microscopy (FESEM) were used to analyze the resulting Co 3 O 4 nanoparticles. These nanoparticles having a crystallite size of 31.94 nm were highly crystalline and had a cubic spinal structure, as indicated by the high-intensity peaks of the XRD spectra. The Co 3 O 4 nanoparticle's remarkable dispersion and spherical shape are highlighted in the FESEM image. Additionally, these biosynthesized Co 3 O 4 nanoparticles have shown efficient antibacterial efficacy against gram (+) and gram (−) bacteria, including Staphylococcus aureus, Streptococcus mutans, Klebsilla pneumonia, and E. coli, along with antifungal efficacy against Aspergillus flavus and Aspergillus Niger under in-vitro environmental conditions. The observed zone of inhibition values against all bacteria and fungi ranged from 22 ± 0.61 mm to 26 ± 0.81 mm and 20 ± 0.42 mm to 33 ± 0.67 mm, respectively. The Senna auriculata flower extract-assisted Co 3 O 4 nanoparticles showed minimum inhibitory concentration values that ranged from 8 to 20 μg/ml against isolated bacteria. This result shows that the Co 3 O 4 nanoparticles exhibited high antibacterial and anti-fungal behaviour with significant differences between other synthesize procedures and the control (Positive control). [ABSTRACT FROM AUTHOR]

To obtain microwave-absorbing materials with high absorptivity, broad bandwidth, and lightweight properties, Co3O4/lotus seedpod carbon (Co3O4/LSC) composites were reduced under a hydrogen pressure of 3 MPa. As the reduction temperature increases, the phases of the Co3O4/LSC composites change from Co3O4 to CoO/Co. At 200 °C (named as the 3200 nanocomposite), partial Co3O4 changes to CoO, the Co3O4 completely transfers into CoO with a little Co detectable at 300 °C (3300 nanocomposite), and the concentration of Co increases more than that of the 3300 nanocomposite once temperature is raised to 400 °C (3400 nanocomposite). Moreover, the morphology of the Co3O4/LSC composites changes from irregular particles to a sintering state in the reduction process. When 3200, 3300, and 3400 nanocomposites are compared, the 3400 nanocomposite exhibits the highest permittivity and best microwave absorption performance: the 3400 nanocomposite exhibits a strong reflection loss of −60.63 dB (2.0 mm, 18.0 GHz) and an absorption bandwidth of 14.10 GHz (4.7 mm, 3.9–18.0 GHz). The hydrogenated LSC/Co3O4 nanocomposite has a strong absorption capacity and wide effective bandwidth, is lightweight, and can be used as a high-performance biomass-based microwave-absorbing material. [ABSTRACT FROM AUTHOR]

D-penicillamine (D-PA) is a sulfur-containing drug that has been used for various health conditions. However, like any medication, overdosing on D-PA can have adverse effects and may require additional treatment. Therefore, developing simple and sensitive methods for sensing D-PA can play a crucial role in improving its efficacy and reducing its side effects. Sensing technologies, such as electrochemical sensors, can enable accurate and real-time measurement of D-PA concentrations. In this work, we developed a novel electrochemical sensor for detecting D-PA by modifying a carbon paste electrode (CPE) with a multi-walled carbon nanotube-Co3O4 nanocomposite, benzoyl-ferrocene (BF), and ionic liquid (IL) (MWCNT-Co3O4/BF/ILCPE). Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CHA) were employed to explore the electrochemical response of D-PA on the developed sensor, the results of which verified a commendable electrochemical performance towards D-PA. Under optimized conditions, the developed sensor demonstrated a rapid response to D-PA with a linear dynamic range of 0.05 μM–100.0 μM, a low detection limit of 0.015 μM, and a considerable sensitivity of 0.179 μA μM−1. Also, the repeatability, stability, and reproducibility of the MWCNT-Co3O4/BF/ILCPE sensor were studied and showed good characteristics. In addition, the detection of D-PA in pharmaceutical and biological matrices yielded satisfactory recoveries and relative standard deviation (RSD) values.

In this study, rosemary leaf extract was effectively used to synthesize cobalt oxide nanoparticles (Co3O4 NPs) using a rapid, low-cost, and environmentally friendly approach. The prepared Co3O4 NPs were examined using various analytical techniques. However, UV spectrum analysis displayed two sharp absorption peaks at ~350 and 745 nm. The dynamic light scattering and zeta potential measurements were used to evaluate the particle size and the effective stabilization of the synthetic nanoparticles in the suspensions. A semi-triangular pyramidal shape of the Co3O4 NPs with a wide particle-size distribution could be observed in the scanning electron microscopy images. The energy-dispersive X-ray spectrum confirmed their successful synthesis, as the experimental atomic percentages agreed with the theoretical values. Moreover, X-ray diffraction analysis revealed that the synthesized Co3O4 NPs had a cubic crystalline structure corroborating that of theoretical Co3O4. Additionally, the Co3O4 NPs were not toxic at ≤62.5 µg/mL for Hep G2 and at ≤31.25 µg/mL for Mcf7. Therefore, these unique environmentally friendly Co3O4 NPs at this safe concentration could be studied in the future for their therapeutic activity. [ABSTRACT FROM AUTHOR]

The green, sustainable, and inexpensive creation of novel materials, primarily nanoparticles, with effective energy-storing properties, is key to addressing both the rising demand for energy storage and the mounting environmental concerns throughout the world. Here, an orange peel extract is used to make cobalt oxide nanoparticles from cobalt nitrate hexahydrate. The orange peel extract has Citrus reticulata, which is a key biological component that acts as a ligand and a reducing agent during the formation of nanoparticles. Additionally, the same nanoparticles were also obtained from various precursors for phase and electrochemical behavior comparisons. The prepared Co-nanoparticles were also sulfurized and phosphorized to enhance the electrochemical properties. The synthesized samples were characterized using scanning electron microscopic and X-ray diffraction techniques. The cobalt oxide nanoparticle showed a specific capacitance of 90 F/g at 1 A/g, whereas the cobalt sulfide and phosphide samples delivered an improved specific capacitance of 98 F/g and 185 F/g at 1 A/g. The phosphide-based nanoparticles offer more than 85% capacitance retention after 5000 cycles. This study offers a green strategy to prepare nanostructured materials for energy applications. [ABSTRACT FROM AUTHOR]

In the present study, nanocomposite (NC) of cetyl trimethyl ammonium bromide (CTAB) coated cobalt oxide nanoparticles (Co3O4 NPs) with graphene oxide (GO), i.e., CTAB@Co3O4@GO, was synthesized for superoxide dismutase mimic (SOD) activity. The NPs and NC were characterized using various analytical tools. X-ray diffraction patterns, Fourier transform infrared and scanning electron microscope–energy dispersive spectrum confirmed the presence of both GO and Co3O4 NPs in NC. Transmission electron microscope micrographs of NC showed GO nanosheets having CTAB-coated Co3O4 NPs on their surface. The NC was evaluated for SOD mimic activity using pyrogallol as a substrate. NC displayed maximum activity as compared to pristine GO and Co3O4 NPs. The results signified that the surfactant coating and embedding the NPs in the GO matrix helped in increasing the interaction of NC with the substrate molecules. Kinetics data was modelled using Michaelis–Menton equation. The calculated Km and Vmax values of NC were 0.0675 mM and 0.146 mol s–1, respectively. Lower value of Michaelis constant Km as compared to the reported values, confirm its edge over other SOD mimics. Thus CTAB@Co3O4@GO NC holds potential for replacing natural enzyme in SOD-based enzymatic assay. [ABSTRACT FROM AUTHOR]

The widespread presence and distribution of metal-based nanoparticles (NPs) in soil is threatening crop growth and food security. However, little is known about the fate of Co 3 O 4 NPs in the soil-soybean system and their phytotoxicity. The study demonstrated the effects of Co 3 O 4 NPs on soybean growth and yield in soil after 60 days and 140 days, and compared them with the phytotoxic effects of Co2+. The results showed that Co 3 O 4 NPs (10–500 mg/kg) had no significant toxic effect on soybeans. Soil available Co content was significantly increased under 500 mg/kg Co 3 O 4 NPs treatment. Compared with Co2+, Co 3 O 4 NPs mainly accumulated in roots and had limited transport to the shoots, which was related to the particle size, surface charge and chemical stability of Co 3 O 4 NPs. The significant accumulation of Co 3 O 4 NPs in roots further led to a significant decrease in root antioxidant enzyme activity and changes in functional gene expression. Co 3 O 4 NPs reduced soybean yield after 140 days, but interestingly, at specific doses, it increased grain nutrients (Fe content increased by 17.38% at 100 mg/kg, soluble protein and vitamin E increased by 14.34% and 16.81% at 10 mg/kg). Target hazard quotient (THQ) assessment results showed that consuming soybean seeds exposed to Co 3 O 4 NPs (≥100 mg/kg) and Co2+ (≥10 mg/kg) would pose potential health risks. Generally, Co 3 O 4 NPs could exist stably in the environment and had lower environmental risks than Co2+. These results help to better understand the environmental behavior and plant effect mechanisms of Co 3 O 4 NPs in soil-plant systems. [Display omitted] • Co 3 O 4 NPs was mainly enriched in soybean roots. • Co 3 O 4 NPs reduced the expression of genes related to stress resistance in soybean. • Co 3 O 4 NPs increased the nutritional quality at a specific dose. • Consuming soybean seeds exposed to Co 3 O 4 NPs (≥100 mg/kg) would pose potential health risks. [ABSTRACT FROM AUTHOR]

The nanostructured Co3O4 particles were prepared by a simple and inexpensive precipitation method, which can be used as electrode materials in pseudocapacitive energy storage devices. The effect of temperature on the crystal structure and morphology of the material was discussed to obtain a suitable condition for the fabrication of the electrodes. The results showed that the Co3O4 calcined at 400 °C (C4) with an average particle size of 34.1 ± 4.0 nm is suitable for electrode fabrication. This is due to the superior electrical conductivity and high purity of the phase structure with a larger specific surface area and porosity compared to the samples calcined at 600 and 800 °C. Moreover, the different oxidation states of Co ions in electrochemical reactions are the main factor for the high capacitance values of the sample. The maximum specific capacitance of 115.3 F/g at a current density of 1 A/g was achieved by the C4 sample. The charge/discharge stability measurements with maximum a of 5000 cycles showed that the sample can achieve excellent retention of specific capacitance of almost 100% for up to 1900 cycles at a current density of 5 A/g. [ABSTRACT FROM AUTHOR]

One of the most important problems facing the restorer in stained glass restoration is the completion of missing glass pieces to which vitreous paints containing metal oxides were applied that require a high temperature for installation, starting from 550 °C and increasing according to the colored oxide nature and the smelter used. The present paper discusses the preparation of blue vitreous paint for nanoparticles Co3O4 to improve its thermal and color properties. It compares the color prepared from the cobalt nano oxide Co3O4 and cobalt oxide CoO mainly used to color the glass blue since the pharaonic periods. Examination and analysis methods, i.e., XRD, FTIR, SEM, EDX, and TEM, were used in characterizing the cobalt nano oxide. STEM, SEM, and stereo microscope were used to study the prepared color samples. Results showed that the particles size of the prepared Co3O4 of 0.78 nm gave an excellent blue color when applied to the glass at a temperature of 620 °C compared to the color resulting from CoO, which was installed at a temperature of 700 °C according to mixing rates. That paved the way for reducing the proportion of the smelter in the color mixture to increase color resistance to weathering deterioration factors, especially moisture. [ABSTRACT FROM AUTHOR]

Homodinuclear cobalt(II) complexes of the tetraiminediphenol macrocycle were synthesized by employing the process of Schiff base condensation reaction of 2,6-diformyl-4-methylphenol and 4-substituted-o-phenylenediamines in the presence of cobalt(II) template. The spectroscopic techniques and mass spectrometry were utilized so as to carry out the characterization for the obtained complexes. On implementing thermal analysis, the complexes were found to exhibit high thermal stability such that they form Co3O4 nanoparticles on thermal decomposition. The diffraction peaks appearing in the X-ray diffraction (XRD) spectra indicated that the nanoparticles were crystalline in nature. Scanning electron microscopy (SEM) was used to identify the surface morphology of Co3O4 nanoparticles. Energy dispersive X-ray spectroscopy (EDS) was undertaken so as to check the chemical purity and stoichiometry of Co3O4 nanoparticles. The size of Co3O4 nanoparticles of all the four complexes was found to be 20–40 nm resulting out of transmission electron microscopy (TEM) which also showed that the nanoparticles were spherical in shape. It has been authenticated with experimental evidence that the substituent present on the macrocycles has made substantial impact on the surface morphology, particle size and band gap of Co3O4. UV–Vis spectroscopic technique clearly reveals the quantum confinement effects of the title material. Synthesis of homogeneous, spherical shaped nanocrystalline Co3O4 using homodinuclear Co(II)complexes of tetraiminediphenol macrocycle as precursor for the first time by thermal decomposition. [ABSTRACT FROM AUTHOR]

In this study, rosemary leaf extract was effectively used to synthesize cobalt oxide nanoparticles (Co3O4 NPs) using a rapid, low-cost, and environmentally friendly approach. The prepared Co3O4 NPs were examined using various analytical techniques. However, UV spectrum analysis displayed two sharp absorption peaks at ~350 and 745 nm. The dynamic light scattering and zeta potential measurements were used to evaluate the particle size and the effective stabilization of the synthetic nanoparticles in the suspensions. A semi-triangular pyramidal shape of the Co3O4 NPs with a wide particle-size distribution could be observed in the scanning electron microscopy images. The energy-dispersive X-ray spectrum confirmed their successful synthesis, as the experimental atomic percentages agreed with the theoretical values. Moreover, X-ray diffraction analysis revealed that the synthesized Co3O4 NPs had a cubic crystalline structure corroborating that of theoretical Co3O4. Additionally, the Co3O4 NPs were not toxic at ≤62.5 µg/mL for Hep G2 and at ≤31.25 µg/mL for Mcf7. Therefore, these unique environmentally friendly Co3O4 NPs at this safe concentration could be studied in the future for their therapeutic activity.

The green, sustainable, and inexpensive creation of novel materials, primarily nanoparticles, with effective energy-storing properties, is key to addressing both the rising demand for energy storage and the mounting environmental concerns throughout the world. Here, an orange peel extract is used to make cobalt oxide nanoparticles from cobalt nitrate hexahydrate. The orange peel extract has Citrus reticulata, which is a key biological component that acts as a ligand and a reducing agent during the formation of nanoparticles. Additionally, the same nanoparticles were also obtained from various precursors for phase and electrochemical behavior comparisons. The prepared Co-nanoparticles were also sulfurized and phosphorized to enhance the electrochemical properties. The synthesized samples were characterized using scanning electron microscopic and X-ray diffraction techniques. The cobalt oxide nanoparticle showed a specific capacitance of 90 F/g at 1 A/g, whereas the cobalt sulfide and phosphide samples delivered an improved specific capacitance of 98 F/g and 185 F/g at 1 A/g. The phosphide-based nanoparticles offer more than 85% capacitance retention after 5000 cycles. This study offers a green strategy to prepare nanostructured materials for energy applications.

The exposure-effect study was conducted to evaluate the effect of Co3O4 nanoparticles on Tetraselmis suecica. The growth suppressing effect has been observed during the interaction between nanoparticles and microalgae as indicated by 72 h EC50 (effective concentration of a chemical at which 50% of its effect is observed) value (45.13±3.95 mg/L) of Co3O4 nanoparticles for Tetraselmis suecica. Decline in chlorophyll a content also indicated the compromised photosynthetic ability and physiological state of microalgae. Further biochemical investigation such as increase in extracellular LDH (lactate dehydrogenase) level, ROS (reactive oxygen species), and levels of membrane lipid peroxidation in treated samples signifies the compromised cellular health and membrane disintegration caused by nanoparticles. Parallel to this, the cell entrapment, membrane damage, and attachment of nanoparticles on cell surface were also visualized by SEM-EDX (scanning electron microscope-energy dispersive X-ray) microscopy. The overall results of this study clearly indicated that Co3O4 nanoparticles might have toxic effects on growth of marine microalgae and other aquatic life forms as well. Hence, release of Co3O4 nanoparticles in aquatic ecosystem and resulting ecotoxic effect should be broadly addressed. [ABSTRACT FROM AUTHOR]

For the efficient synthesis of transition-metal cobalt oxide nanoparticles (Co3O4 NPs) without using any costly and toxic solvent or complicated equipment, the co-precipitation method was used in this work. Using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV–Vis spectrophotometry, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), the prepared Co3O4 NPs were characterized and identified. The influence of prepared Co3O4 NPs on the developmental synthesis of some selenopyridine/quinoline derivatives under different microwave irradiation powers and irradiation times was investigated via click (reaction) chemistry. The reusable Co3O4 nanoparticles have high catalytic activity under microwave irradiation for the synthesis of organoselenium compounds with higher yields (> 90%), milder reaction conditions and shorter time without significantly decreasing the reaction rates and yields. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel N -doped CN@Co-Co 3 O 4 /CNTs are prepared by the simple and self-template method. • The CN@Co-Co 3 O 4 /CNTs with CNTs and CNs effectively prevents the re-stacking of CNs. • The CN@Co-Co 3 O 4 /CNTs exhibits high discharge capacity (460 mAh g−1 at 5000 mA g−1) • The CN@Co-Co 3 O 4 /CNTs has excellent higher-rate capacity (401.0 mAh g−1 at 2000 mA g−1 and 329.0 mAh g−1 at 5000 mA g−1). A novel N -doped graphene-like carbon nanosheets (CNs) and carbon nanotubes (CNTs)-encapsulated Co-Co 3 O 4 nanoparticles (NPs) (CN@Co-Co 3 O 4 /CNTs) were synthesized successfully by a simple hydrothermal and annealing method with graphite carbon nitride (g-C 3 N 4) as self-template. By annealing Co2+/g-C 3 N 4 under N 2 atmosphere, g-C 3 N 4 was transformed into CN/CNTs, and Co2+ was reduced into CoNPs which were embedded in CNs. Further annealing in air, a shell of Co 3 O 4 was formed around CoNPs. The amount of CNs, CNTs, and CoNPs can be adjusted by changing the ratio of Co2+ in Co2+/g-C 3 N 4. The graphene-like CNs provided a large number of active sites and a large specific surface area for loading lots of small CoNPs uniformly. The CNTs with a diameter of 100 nm could not only improve the conductivity but also provide a buffer space for the aggregation and volume expansion of Co 3 O 4. CNTs also enlarged the interlayer distance of CNs, which prevented the re-stacking of CNs and provided great convince for the intercalation and de-intercalation of Li+. When applied for anode material of lithium-ion batteries, CN@Co-Co 3 O 4 /CNTs exhibited a high discharge capacity of 460.0 mAh g−1 at 5000 mA g−1 after 300 cycles with a Coulombic efficiency of 98% and excellent higher-rate capacity (401.0 mAh g−1 at 2000 mA g−1 and 329.0 mAh g−1 at 5000 mA g−1). [ABSTRACT FROM AUTHOR]

Co 3 O 4 nanoparticles embedded in 3D ordered macro-/mesoporous TiO 2 have been synthesized through a in situ method form dual templates and the anode shows good electrochemical performance in Li-ion capacitor. [Display omitted] • Co 3 O 4 nanoparticles embedded in 3D ordered macro-/mesoporous TiO 2 are prepared. • The Co 3 O 4 @TiO 2 shows enhanced rate capability and cycling performance in LIBs. • The Co 3 O 4 @TiO 2 composite exhibits great electrochemical performance for LICs. Lithium-ion hybrid capacitors (LICs) have gained increasing focus owing to their high energy/power densities. The development of anodes with superior rate capability is an effective way to surmount the kinetic mismatch between anodes and cathodes, and thus, enhancing the energy/power densities. Herein, Co 3 O 4 nanoparticles embedded in three-dimensionally (3D) ordered macro-/mesoporous TiO 2 (Co 3 O 4 @TiO 2) are synthesized through an in situ method from dual templates. Differing from the composite prepared by loading active nanoparticles on support, Co 3 O 4 nanoparticles are embedded in TiO 2 framework, which can improve the stability of the electrode. Furthermore, the hierarchically porous structure of TiO 2 is in favor of the rapid diffusion of ions and electrolyte. As a result, The Co 3 O 4 @TiO 2 -2 composite with an optimized Co 3 O 4 content (~25 wt%) delivers a high capacity of 944.1 mAh g−1 after 100 cycles at 0.1 A g−1 and high-rate capability (405.7 mAh g−1 after 1000 cycles at 5 A g−1). The LIC assembled with Co 3 O 4 @TiO 2 -2 anode and activated carbon (AC) cathode delivers high energy/power densities (maximum, 87.9 Wh kg−1/10208.9 W kg−1) and great cycle stability (88.1%, 6000 cycles, 0.5 A g−1). [ABSTRACT FROM AUTHOR]

In this paper, the different valent metal-cations (Zn2+, In3+ and Zr4+) doped porous Co 3 O 4 nanostructures were synthesized through the pyrolysis of ZIF-67 metal–organic framework (MOF). The influence of the different valence and doping content of metal-cations on the morphology, microstructures and gas-sensing performance of Co 3 O 4 sensors is discussed in detail. The Zr-doped Co 3 O 4 nanostructures present the higher specific surface area for the smaller average grain size, and the toluene gas-sensing performance of Co 3 O 4 nanostructures is significantly improved with the high-valent Zr-doping. The high valence Zr-doping greatly improves the toluene gas-sensing properties, which Co 2.717 Zr 0.189 O 4 sensor exhibits the highest response value of 94.58 to 100 ppm toluene gas (3.8-fold of Co 3 O 4 sensor). The donor Zr-doping to p-type Co 3 O 4 nanostructures optimizes the hole distribution and further affects Fermi level. Combining with the more oxygen adsorption from the high specific surface area, the resistance in air greatly decreases and resistance in toluene gas increases. [ABSTRACT FROM AUTHOR]