Cobalt Nanoparticles Research Articles

Characteristics and Magnetic Properties of Carbon-Coated Cobalt Nanoparticles Deposited on Silica

Characteristics and Magnetic Properties of Carbon-Coated Cobalt Nanoparticles Deposited on Silica

Ammonia Decomposition via MOF-derived Photothermal Catalysts.

Three cobalt-based metal-organic framework (MOF)-derived catalysts were developed for photothermal hydrogen production via ammonia decomposition. The selected MOFs were from distinct families, featuring carboxylate and imidazole linkers, and diverse in terms of porosity. The resulting catalysts consisted of uniform and homogeneously dispersed cobalt nanoparticles embedded within a carbon matrix. The carboxylate-based MOF-74 derived catalyst showed the highest initial activity, but gradually deactivated. ZIF-67 derived catalyst, however, demonstrated stable performance. The synergy between photo and thermal effects was confirmed. Additionally, this catalyst was found to be also effective in ammonia synthesis, potentially closing the loop for sustainable ammonia utilization.

Heat transfer analysis of hybrid nanofluid under the effects of surface roughness along with velocity and thermal slips

AbstractSurface roughness has a great impact on the peristaltic motion of nanofluid flow and plays an important role in engineering, manufacturing, and material sciences. During tissue engineering, imaging techniques, implant surface finish, surgical instrument texture, and tissue engineering, and so forth. This study explores the effects of electrical double layers, surface roughness, velocity slip, and thermal slip to investigate the heat transfer rate of cobalt and alumina nanoparticles with water through uniform and nonuniform horizontal tubes. In the present study, the Jeffrey nanofluid flow model is chosen to investigate the heat transfer phenomenon of hybrid nanofluids based on alumina and cobalt nanoparticles suspension in water. The effects of electroosmosis, surface roughness, viscous dissipation, heat source/sink parameter, velocity, and thermal slips are also under consideration during the peristaltic motion of hybrid nanofluid in uniform and nonuniform tubes. The mathematical software MATHEMATICA 13.3 is utilized to find the exact solution and graphical results to investigate the complicated flow behavior. It is noticed that the velocity near the walls of the tube is lower for the surface roughness parameter and higher in the core part. The behavior of velocity for the remaining parameter is the opposite. The temperature of the current fluid flow increases for all parameters except the surface roughness parameter. The effects of velocity for hybrid nanofluid are prominent as compared with nanofluid in the core part. The temperature profile and heat transfer rate for hybrid nanofluids are lower as compared with nanofluids, which shows the cooling effects. This study is beneficial for hyperthermia, gene therapy, drug delivery, and tissue engineering.

Multifunctional carbon nanotube arrays on kapok-derived carbon microtube composites for efficient electromagnetic wave absorption and Cu(II) removal

To cope with different environments of application, electromagnetic wave absorption (EWA) materials with multifunctionality have attracted a wide range of interests. And excessive heavy metal ions in aqueous solutions seriously affect people’s health and pose a major challenge to environmental safety. In this study, carbon microtube/carbon nanotube (CMT/CNT) composites were fabricated via carbonization and chemical vapor deposition (CVD) methods. The CNT wrapped with cobalt nanoparticles were grown in situ on the CMT which derived from kapok fiber. By varying the concentration of cobalt precursors, the EWA and Cu(II) adsorption performances of CMT/CNT can be efficiently tuned. Optimizing the cobalt content to 2 wt% resulted in a minimum reflection loss (RL) of −66.14 dB at a matching thickness of 1.91 mm, with an effective absorption bandwidth (EAB) of 5.35 GHz. The adsorption capacity of Cu(II) by the CMT/CNT composite can reach 102.01 mg/g when the initial Cu(II) concentration is 500 mg/L. This research not only shows great promise for applications in the field of EWA materials but also holds significant potential for heavy metal ion removal and as a catalyst carrier, among other areas.

Rational construction of porous cobalt nanoparticle integrated nitrogen doped hollow carbon nanostructures for peptide agonist exendin-4 biosensing

Rational construction of porous cobalt nanoparticle integrated nitrogen doped hollow carbon nanostructures for peptide agonist exendin-4 biosensing

Realizing radio-frequency epsilon-near-zero response via embedding cobalt nanoparticles into polyimide

Realizing radio-frequency epsilon-near-zero response via embedding cobalt nanoparticles into polyimide

Removal of bisphenol A through peroxymonosulfate activation with N-doped graphite carbon spheres coated cobalt nanoparticles catalyst: Synergy of nonradicals

Removal of bisphenol A through peroxymonosulfate activation with N-doped graphite carbon spheres coated cobalt nanoparticles catalyst: Synergy of nonradicals

Quercetin has a protective impact on human umbilical vein endothelial cells against tungsten carbide cobalt nanoparticle-induced cytotoxicity, oxidative stress, apoptosis

Oxidative stress is a pivotal factor in the pathogenesis of various cancer diseases. In fact, oxidative DNA damage is described as the type of damage probably to occur in cancer cells. This study examined the protective impact of the polyphenolic compound quercetin on human umbilical vein endothelial (HUVEC) cells against tungsten carbide cobalt nanoparticles (WC-Co NPs)-induced oxidative stress, cytotoxicity, and apoptosis. One of the most often used models for studying endothelial cells in vitro is the human umbilical vein epithelial cell. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to measure the size of the NPs prior to WC-Co NPs treatment. WC-Co NPs had a polygonal form and measured 45.26 ± 1 nm in size. Using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT),neutral red uptake(NRU) and lactate dehydrogenase (LDH) assays, the cytotoxicity of WC-Co NPs on HUVECs cells was assessed. The cytotoxicity of NPs increased in a concentration-dependent way. The MTT result was used to calculate the median inhibitory concentration (IC50) for HUVEC cells at 24 h, which came out to be 23.14 μg/ml. Intracellular reactive oxygen species(ROS) and lipid peroxidation(LPO) levels were elevated at 17 g/ml WC-Co NPs and then reduced in HUVECs cells upon immediate exposure to 150 µM quercetin (QR). Using JC-1 staining, the loss of mitochondrial membrane potential(MMP) in control, WC-Co NPs alone and WC-Co NPs plus QR exposed cell were evaluated. In HUVECs cells, maximum apoptotic cells were seen at increasing NPs concentrations. Based on the impacts of NPs on HUVECs cells, the data suggests that QR may work on the process of scavenging ROS, which is responsible for DNA repair. Consequently, the above findings highlight the significance of these QR as defenses against DNA damage brought on by oxidative stress, which frequently happens in a number of cancer disorders.

Hybrid nanofluid flow over a vertical plate through porous medium in a conducting and chemically reacting field with radiation absorption and variable suction

This research investigates the flow of an electrically conductive hybrid nanofluid across a porous plate that is in motion and experiencing temperature and velocity slip. In addition, the impacts of radiation absorption and variable suction are included. The heat transfer phenomena have been investigated using a hybrid nanofluid consisting of distilled water, brass, and cobalt. The behavior of the hybrid nanofluid is determined by the Tiwari-Das model. The graphs are drawn with the help of MATLAB software. It is noticed that compared to Cu3Zn2−TiO2 hybrid nanofluid, C−TiO2 with distilled water exhibits the optimum heat transfer by 5.72 % for fixed values of S and R. The temperature reaches at its maximum at y = 0.4520. Remarkably, the maximum improvement of 42.9547 % is noted for Ra=0.8,ϕ1=ϕ2=0.02,S=0.2,h2=0.5. The addition of brass and cobalt nanoparticles to a base fluid may considerably lower its operational temperature. The hybrid nanofluid composed of carbon-titanium oxide shows the greatest increase in heat transmission, but the hybrid nanofluid made of brass titanium-oxide indicates just a modest improvement. The buoyancy forces enhance the growth of both the momentum and thermal boundary layers. As the Cu3Zn2−Co hybrid nanofluid acts as a coolant, which can be used in the cooling of the battery.

In Situ Construction of Highly Dispersed Pd on Cobalt Nanoparticle on Hollow Functional Cubic Graphene by Double Framework for ORR.

Developing advanced functional carbon materials is essential for electrocatalysis, caused by their vast merits for boosting many key energy conversion reactions. Herein, the covalent organic frameworks (COFs) is utilized on metal-organic frameworks (MOFs) as the template, under the controllable metal atoms thermal migration process successfully in situ constructs Pd-Co alloy nanoparticles on hollow cubic graphene. The electrocatalytic oxygen reduction reaction (ORR) evaluation showed excellent performances with a half-wave potential of 0.866V, and a limited current density of 4.975mA cm-2, that superior to the commercial Pt/C and Co nanoparticles. The contrast experiments and X-ray absorption spectrum demonstrated the aggregated electrons at highly dispersed Pd atoms on Co nanoparticle that promoted the main activities. This work not only enlightens the novel carbon materials designing strategies but also suggests heterogeneous electrocatalysis.

Defective wood-based chainmail electrocatalysts boost performances of seawater-medium Zn-air batteries

A high-activity and stable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalyst is critical for seawater-based Zn-air batteries (ZABs). Herein, we report a wood-derived chainmail electrocatalyst containing defective nitrogen-doped carbon nanotubes encapsulating cobalt nanoparticles (Co@D-NCNT/CW) to enhance the ORR/OER activity and stability in seawater medium. During the preparation process, the introduction and removal of Zn increased the defect sites and pyridine N content in the carbon material, modulating charge distribution and influencing the adsorption and activation processes. The highly ordered open channels in Co@D-NCNT/CW promoted mass transfer of reactants and accelerated gas diffusion. The resultant chainmail electrocatalyst exhibited impressive bifunctional ORR and OER activities with an ultra-low gap of 0.67 V in seawater-based alkaline electrolyte. The Co@D-NCNT/CW-assembled seawater-based rechargeable liquid ZABs demonstrated a maximum power density of 245.3 mW cm−2 and a long-term cycling performance over 500 h. The seawater-based all-solid-state ZABs achieved the maximum power density of 48.2 mW cm−2 and stabilized over 30 h. Density functional theory revealed that the presence of defects and pyridine nitrogen in Co@D-NCNT/CW modulated the electronic structure of Co, optimizing the binding affinity of the Co sites with intermediates and weakening Cl− adsorption. This work provides a new approach to preparing high-activity and stable ORR/OER electrocatalyst utilizing wood nanostructures, boosting the development of seawater-based ZABs.

Visualizing dynamic alterations of vitreous viscosity during elevated intraocular pressure in glaucoma with a Near-infrared/Magnetic resonance imaging dual-modal nanoprobe

Glaucoma is a chronic progressive disease leading to irreversible visual impairment and blindness. High intraocular pressure (IOP) resulting from abnormally high outflow resistance is a major risk factor for glaucoma development, however, it is unclear how IOP elevation influences the structure and function of the retina and the optic nerve via vitreous humor located between the lens and retina in the eye. To understand vitreous biomechanical and stimulus response toward IOP elevation, we developed a novel near-infrared (NIR)/MRI dual-modal nanoprobe, DTA/P-NCA/17F@Co, which is composed of N, N-dimethyl-4(thien-2-yl)-aniline group (DTA) as NIR fluorophore and the fluorine-based polyamino acid cobalt nanoparticles (P-NCA/17F@Co) as T2 contrast agent. These nanoprobes exhibit good biocompatibility, low surface energy characteristics, and viscosity-responsive NIR emission and T2 relaxation values. The intrinsic viscosity-sensitivemechanismof nanoprobes was ascribed to constrained molecular motion in high-viscosity vitreous chamber, which causes enhanced fluorescence emission and shortened T2 relaxation times. By using its ability for dual-modal visualization of viscosity, we achieved non-invasive in vivo monitoring the changes in vitreous viscosity during elevated IOP in a glaucoma rat model. In vivo experiments validated that vitreous viscosity is very strongly correlated with IOP elevation induced by glaucoma, much earlier than structural and functional change in the retina. Our findings revealed that IOP elevation induced the increase of vitreous viscosity, indicating that monitoring vitreous viscosity is key to the glaucoma model. This study not only provides versatile nanoprobes for dual-modal visualization of biomechanical properties of the vitreous humor in its native environment, but also shows great potential in the early diagnosis of glaucoma.

Green Synthesis and Characterization of Cobalt Nanoparticles Using Butea Monosperma Flower Extract and their Biocompatibility Studies

Green Synthesis and Characterization of Cobalt Nanoparticles Using Butea Monosperma Flower Extract and their Biocompatibility Studies

Facile synthesis of Co/rGO, Au/rGO, and CoAu/rGO nanocomposites for precise determination of Arsenic(III) in water systems

Cobalt (Co), gold (Au), and cobalt-gold (CoAu) nanoparticles were deposited on reduced graphene oxide (rGO) by a facile and scalable procedure. The synthesised nanocomposites (Co/rGO, Au/rGO, and CoAu/rGO) were used as electrode materials for detecting trace amounts of arsenic (As(III)) ions in water samples. All three electrodes responded to the presence of As(III) in an acidic medium (different acids of the same concentration, then chosen acid at different concentrations). A detailed optimization of the conditions was continued with the CoAu/rGO electrode which showed the best response in terms of the best defined peak indicating the oxidation of As(0) to As(III) and the highest current. The electrode was tested in a wide range of concentrations (30–1000 µM), where two areas of linearity and limits of detection were obtained (for low- and high- concentrations). Moreover, this electrode showed the ability to detect As(III) ions in the presence of Cu(II), as an interference model as well as a satisfactory electrochemical response, in terms of a clear peak corresponding to the oxidation of As(0) to As(III) in a real sample.

Improving the anaerobic digestion of sewage sludge by adding cobalt nanoparticles

ABSTRACT This work evaluated the effects of cobalt nanoparticles (CoNPs) (0.025–7 mg/gVS) on the intensification of sewage sludge anaerobic digestion (AD) using biochemical methane potential (BMP) tests. This study was motivated by the need to improve the efficiency and stability of anaerobic digestion of sewage sludge, a critical process in waste management and renewable energy production. The effects at doses less than 2 mg/gVS were not substantial, but 3–7 mg/gVS improved the performance. The maximum biogas yield was 232 mL/gVS (at a dose of 7 mg/gVS), whereas it was 132 mL/gVS in the control (zero dose). Similarly, the reductions in the volatile solids and methane contents reached maxima of 16 and 74.3%, respectively. The analyses of volatile fatty acids, redox potential, and electron transfer system activity indicated that the addition of CoNPs stimulated the early stages of AD. Finally, acetate consumption and the increase in CH4 content suggested that CoNPs positively affected system stability and acetoclastic methanogenesis. That is, CoNPs effectively intensified the behaviour and stability of the anaerobic process. The novelty of this research lies in the comprehensive evaluation of the effects of CoNPs across a wide range of doses on sewage sludge AD, providing new insights into the optimisation of this process for increased biogas production and organic matter reduction.

HMGB1 derived from lung epithelial cells after cobalt nanoparticle exposure promotes the activation of lung fibroblasts

We have previously demonstrated that exposure to cobalt nanoparticles (Nano-Co) caused extensive interstitial fibrosis and inflammatory cell infiltration in mouse lungs. However, the underlying mechanisms of Nano-Co-induced pulmonary fibrosis remain unclear. In this study, we investigated the role of high-mobility group box 1 (HMGB1) in the epithelial cell-fibroblast crosstalk in Nano-Co-induced pulmonary fibrosis. Our results showed that Nano-Co exposure caused remarkable production and release of HMGB1, as well as nuclear accumulation of HIF-1α in human bronchial epithelial cells (BEAS-2B) in a dose- and a time-dependent manner. Pretreatment with CAY10585, an inhibitor against HIF-1α, significantly blocked the overexpression of HMGB1 in cell lysate and the release of HMGB1 in the supernatant of BEAS-2B cells induced by Nano-Co exposure, indicating that Nano-Co exposure induces HIF-1α-dependent HMGB1 overexpression and release. In addition, treatment of lung fibroblasts (MRC-5) with conditioned media from Nano-Co-exposed BEAS-2B cells caused increased RAGE expression, MAPK signaling activation, and enhanced expression of fibrosis-associated proteins, such as fibronectin, collagen 1, and α-SMA. However, conditioned media from Nano-Co-exposed BEAS-2B cells with HMGB1 knockdown had no effects on the activation of MRC-5 fibroblasts. Finally, inhibition of ERK1/2, p38, and JNK all abolished MRC-5 activation induced by conditioned media from Nano-Co-exposed BEAS-2B cells, suggesting that MAPK signaling might be a key downstream signal of HMGB1/RAGE to promote MRC-5 fibroblast activation. These findings have important implications for understanding the pro-fibrotic potential of Nano-Co.

Combination of nanoparticles with single-metal sites synergistically boosts co-catalyzed formic acid dehydrogenation

The development of hydrogen technologies is at the heart of a green economy. As prerequisite for implementation of hydrogen storage, active and stable catalysts for (de)hydrogenation reactions are needed. So far, the use of precious metals associated with expensive costs dominates in this area. Herein, we present a new class of lower-cost Co-based catalysts (Co-SAs/NPs@NC) in which highly distributed single-metal sites are synergistically combined with small defined nanoparticles allowing efficient formic acid dehydrogenation. The optimal material with atomically dispersed CoN2C2 units and encapsulated 7-8 nm nanoparticles achieves an excellent gas yield of 1403.8 mL·g−1·h−1 using propylene carbonate as solvent, with no activity loss after 5 cycles, which is 15 times higher than that of the commercial Pd/C. In situ analytic experiments show that Co-SAs/NPs@NC enhances the adsorption and activation of the key intermediate monodentate HCOO*, thereby facilitating the following C-H bond breaking, compared to related single metal atom and nanoparticle catalysts. Theoretical calculations show that the integration of cobalt nanoparticles elevates the d-band center of the Co single atoms as the active center, which consequently enhances the coupling of the carbonyl O of the HCOO* intermediate to the Co centers, thereby lowering the energy barrier.

NiCo@EG-based composite PCMs with boosted thermal conductivity and photothermal conversion efficiency for solar energy harvesting

The application of phase change materials (PCMs) in solar energy is hampered by challenges such as insufficient photothermal conversion efficiency, low thermal conductivity and leakage. In this study, a novel composite PCMs based on NiCo@EG were prepared to solve the problems of low thermal conductivity, high leakage rate and inefficient photothermal performance. The NiCo@EG is obtained through calcination of the product of Ni-Co-BTC in-situ on expanded graphite (EG). In the composite PCMs, the octadecanol (OD) acts as a latent heat storage unit, the EG retains its porous network structure as an encapsulating skeleton. The nickel and cobalt nanoparticles derived from Ni-Co-BTC bimetallic organic frameworks are uniformly fixed on the surface of the EG, which could not only construct multiple thermal conduction pathways, but also enhance the photon-trapping ability. Benefiting from the synergy effect of nickel, cobalt metal nanoparticles and EG, the prepared OD/NiCo@EG-550 composite PCMs display high latent heat (168.3 J/g), excellent photothermal conversion efficiency (98.71 %), and improved thermal conductivity of 12.873 W/(m·K). Furthermore, the composite PCMs demonstrate exceptional shape stability, thermal stability, and robust thermal reliability. In summary, the high-efficiency photothermal composite PCMs display significant potential in improving the utilization of solar energy.

Evaluation of physiochemical and in-vitro characteristics of Ixora Coccinea mediated Co3O4 nanoparticles for photocatalytic degradation of toxic textile dye effluents

Discharging colored wastewater from the textile industry into water bodies disrupts the natural ecosystem and reduces the productivity of aquatic life. It is challenging to degrade complex dye molecules, including pathogens and bacteria. This research article deals with the photocatalytic activity of cobalt oxide nanoparticles mediated Ixora coccinea plant extract for industry effluent treatment applications. The green synthesized nanoparticles were found to have high crystallinity and purity, cubic crystal structure, and spherical morphology with 21.5 nm crystallite size. Further, the biological properties, such as antibacterial, antioxidant, and bacterial growth inhibition activity, were evaluated. With 88 % and 83 % bacterial growth inhibition, the antibacterial activity showed a maximum bacterial zone inhibition of 31 ± 0.4 mm for positive and 29 ± 0.3 mm for harmful bacterial strains. Then, the level of scavenging free radicals measured about 93.87 %. The photocatalytic activity was evaluated against the textile dyes under direct sunlight irradiation. The maximum dye degradation was achieved for Alizarin red (85.2 %), Crystal violet (90.7 %), Reactive black (94.5 %), and Rhodamine B (96.4 %) dyes at the end of 90 min of irradiation. Moreover, this research paper introduces a method for creating cobalt nanoparticles using natural and sustainable approaches. These nanoparticles have potential in several fields, such as medicine, catalysis, and water remediation.

Long Noncoding RNA NR_030777 Alleviates Cobalt Nanoparticles-Induced Neurodegenerative Damage by Promoting Autophagosome-Lysosome Fusion.

Potential exposure to cobalt nanoparticles (CoNPs) occurs in various fields, including hard alloy industrial production, the increasing use of new energy lithium-ion batteries, and millions of patients with metal-on-metal joint prostheses. Evidence from human, animal, and in vitro experiments suggests a close relationship between CoNPs and neurotoxicity. However, a systematic assessment of central nervous system (CNS) impairment due to CoNPs exposure and the underlying molecular mechanisms is lacking. In this study, we found that CoNPs induced neurodegenerative damage both in vivo and in vitro, including cognitive impairment, β-amyloid deposition and Tau hyperphosphorylation. CoNPs promoted the formation of autophagosomes and impeding autophagosomal-lysosomal fusion in vivo and in vitro, leading to toxic protein accumulation. Moreover, CoNPs exposure reduced the level of transcription factor EB (TFEB) and the abundance of lysosome, causing a blockage in autophagosomal-lysosomal fusion. Interestingly, overexpression of long noncoding RNA NR_030777 mitigated CoNPs-induced neurodegenerative damage in both in vivo and in vitro models. Fluorescence in situ hybridization assay revealed that NR_030777 directly binds and stabilizes TFEB mRNA, alleviating the blockage of autophagosomal-lysosomal fusion and ultimately restoring neurodegeneration induced by CoNPs in vivo and in vitro. In summary, our study demonstrates that autophagic dysfunction is the main toxic mechanism of neurodegeneration upon CoNPs exposure and NR_030777 plays a crucial role in CoNPs-induced autophagic dysfunction. Additionally, the proposed adverse outcome pathway contributes to a better understanding of CNS toxicity assessment of CoNPs.