Cobalt Nanoparticles Research Articles

Synergistic effect of iron phthalocyanine and ultrafine cobalt nanoparticles for efficient CO2 electroreduction to syngas

Developing efficient electrocatalysts for CO2 electroreduction to syngas with a specific H2/CO ratio over a wide potential window is desperately required but still challenging. In this work, a series of dual-site catalysts composed of iron phthalocyanine (FePc) and ∼18 nm Cobalt nanoparticles (Co NPs) anchored on N-doped carbon matrix has been constructed from zeolitic imidazolate framework-67 (ZIF-67). Benefiting from the synergistic effect of FePc and Co NPs, the derived FePc/Co@N–C catalyst shows impressive capability for CO2 electrolysis to syngas. By varying the pyrolysis temperatures (600–800 °C) of ZIF-67 and the mass ratio of Co@N–C to FePc (1–3), an adjustable H2/CO ratio of 2–4 is obtained, and the value can be maintained stable within a potential window of −0.66 to −0.86 V vs. RHE in an H-type cell. Moreover, this electrocatalyst exhibits favorable stability without distinct performance decay. When conducted in a flow cell, an enhanced catalytic activity is demonstrated with an industrial current density (>100 mA cm−2) at −0.8 V vs. RHE and a steady H2/CO ratio of 2 from −0.4 to −0.6 V vs. RHE. This work provides a promising strategy of designing bifunctional electrocatalysts for syngas generation with stable H2/CO ratio across a wide potential range.

Pt atomic clusters/MoS2 nanosheets/Co-doped hollow carbon nanofibers for high-current–density alkaline hydrogen production

The application of layered molybdenum disulfide (MoS2) in catalytic hydrogen production has attracted great interest, while their catalytic properties are limited by poor electron conductivity and a few catalytically active sites. In this work, we demonstrated a highly active electrocatalyst for large-scale hydrogen production, consisting of two-dimensional (2D) Pt-MoS2 nanosheets along one-dimensional (1D) cobalt nanoparticle integrated carbon hollow nanofibers (Co@CHNF). The as-prepared Pt-MoS2-Co@CHNF had a large specific surface area (44.5 m2 g−1). X-ray photoelectron spectrometer (XPS) and spherical aberration corrected transmission electron microscope (AC-STEM) demonstrated that Pt atomic clusters (Pt ACs) were doped on MoS2 nanosheets by thermodynamically induced spontaneous interfacial redox between MoS2 and H₂PtCl₆. The Pt-MoS2-Co@CHNF based catalysts exhibited an overpotential as low as 91 mV for 10 mA cm−2 and 258 mV for 200 mA cm−2 in 1 M KOH electrolyte, and there is no significant floating for catalytic active with 14 h continuous operation, which demonstrates its excellent long-term operation durability, significantly superior to the previously reported state-of-the-art Co-based or Mo-based catalysts. In particular, the self-supporting binder-free Pt-MoS2-Co@CHNF catalyst-based electrode showed an ultra-high current density of 500 mA cm−2 at a low overpotential of 301 mV, without any decrease after 24 h operation at 500 mA cm−2 in 1 M KOH seawater electrolyte, representing a great potential for large-scale seawater hydrogen production.

Cobalt Nanoparticles Encapsulated in the Biomass-Derived Carbon: An Efficient and Bifunctional Electrocatalyst for Overall Water Splitting

Cobalt Nanoparticles Encapsulated in the Biomass-Derived Carbon: An Efficient and Bifunctional Electrocatalyst for Overall Water Splitting

Cobalt nanoparticles intercalation coupled with tellurium-doping MXene for efficient electrocatalytic water splitting

Nowadays, the inherent re-stacking nature and weak d-p hybridization orbital interactions within MXene remains significant challenges in the field of electrocatalytic water splitting, leading to unsatisfactory electrocatalytic activity and cycling stability. Herein, this work aims to address these challenges and improve electrocatalytic performance by utilizing cobalt nanoparticles intercalation coupled with enhanced π-donation effect. Specifically, cobalt nanoparticles are integrated into V2C MXene nanosheets to mitigate the re-stacking issue. Meanwhile, a notable charge redistribution from cobalt to vanadium elevates orbital levels, reduces π*-antibonding orbital occupancy and alleviates Jahn-Teller distortion. Doping with tellurium induces localized electric field rearrangement resulting from the changes in electron cloud density. As a result, Co-V2C MXene-Te acquires desirable activity for hydrogen evolution reaction and oxygen evolution reaction with the overpotential of 80.8 mV and 287.7 mV, respectively, at the current density of −10 mA cm−2 and 10 mA cm−2. The overall water splitting device achieves an impressive low cell voltage requirement of 1.51 V to obtain 10 mA cm−2. Overall, this work could offer a promising solution when facing the re-stacking issue and weak d-p hybridization orbital interactions of MXene, furnishing a high-performance electrocatalyst with favorable electrocatalytic activity and cycling stability.

Accelerated peroxymonosulfate activation over defective perovskite with anchored cobalt nanoparticles for organic contaminant removal

In this study, a novel perovskite oxide (Co@D-PBSC) for activation peroxymonosulfate (PMS) to degrade organic pollutants in wastewater was developed. Cobalt nanoparticles (Co NPs) and oxygen vacancies (OVs) were introduced to the perovskite oxide lattice via a non-stoichiometric ratio and separate-out strategy. The OVs and Co NPs provided abundant active sites for the activation of PMS and the generation of reactive oxygen species. The Co metal-OVs bridge promote the adsorption of PMS, meanwhile, Co nanoparticles accelerate the Co2+/Co3+ redox cycle, resulting in the production of the main reactive substance, sulfate radicals (SO4•−). The results of catalytic experiments showed that 85 % of ofloxacin (OFX) degradation efficiency was obtained within 1 min at 0.1 g/L Co@D-PBSC, 0.3 g/L PMS, 20 mg/L OFX (150 mL), and solution pH 7.0, which indicated that Co@D-PBSC/PMS system exhibits excellent performance. This work demonstrated an efficient perovskite catalyst for PMS activation in wastewater treatment and provided a useful catalyst design strategy for the advanced oxidation processes (AOPs).

Dual green reduction mechanisms to prepare rGO-CoNPs nanocomposite using pomegranate peel extract: Electrochemical and photocatalysis applications

This paper presents a novel, eco-friendly, cost-effective method for synthesizing a special nanohybrid material based on reduced graphene oxide (rGO) and cobalt nanoparticles (CoNPs) using pomegranate peel as a waste food source. The study proposed two reactional mechanisms that suggest ascorbic and gallic acid are directly involved in the reduction process. Electrochemical studies revealed a remarkable performance indicating its potential for electrochemical sensing applications. Additionally, the nanocomposite exhibited excellent photocatalytic activity towards the degradation of methylene blue demonstrating its potential as an effective photocatalyst for environmental application. The green approach presented in this study is effective for synthesizing high-performance nanomaterials.

Synergistic restriction of polysulfides enabled by cobalt@carbon spheres embedded CNTs: A facile approach for constructing sulfur cathodes with high sulfur content

Despite the bright fortune of lithium-sulfur (Li-S) batteries as one of the next-generation energy storage systems owing to the ultrahigh theoretical energy density and earth-abundance of sulfur, crucial challenges including polysulfide shuttling and low sulfur content of sulfur cathodes need to be overcome before the commercial survival of sulfur cathodes. Herein, cobalt/carbon spheres embedded CNTs (Co-C-CNTs) are rationally designed as multifunctional hosts to synergistically address the drawbacks of sulfur cathodes. The host is synthesized by a facile pyrolysis using Co(OH)2 template and followed with the controllable etching process. The hierarchical porous structure owning high pore volume and surface area can buffer the volume change, physically confine polysulfides, and provide conductive networks. Besides, partially remained metallic cobalt nanoparticles are favorable for chemical adsorption and conversion of polysulfides, as validated by density functional theory simulations. With the combination of above merits, the S@Co-C-CNTs cathodes with a high sulfur content of 80 wt% present a superior initial capacity (1568 mAh g−1 at 0.1C) with ultrahigh 93.6% active material utilization, and excellent rate performance (649 mAh g−1 at 2C), providing feasible strategies for the optimization of cathodes in metal-sulfur batteries.

Stabilizing magnetic order of cobalt-based anisotropic nanoparticles prepared using NaBH4 as a reducing agent

A one-pot chemical method was used to prepare cobalt nanoparticles (Co NPs) by employing sodium borohydride (NaBH4) as a reducing agent, as well as graphite and activated carbon as stabilizer materials. The resulting NPs were characterized by XRD, FE-SEM, EDX mapping and VSM measurements before and after annealing under a mixture of argon and hydrogen atmosphere at 600 ℃, in order to study their structural, morphological, and magnetic properties. This study focused on the shape and size of Co NPs, involving the formation of Co and Co3O4 phases with the effect of oxygen as the main factor that can significantly contribute to the magnetic anisotropy. Co NPs exhibited a high saturation magnetization (Ms) value after performing the annealing process, achieving Ms> 99 emu/g when using the graphite stabilizer. The results indicate that surface atoms play a significant role in the modification of magnetic characteristics of Co NPs.

Highly porous layered carbon nanocomposites from the self-assembly of a poly(amic acid) for efficient oxygen reduction reaction catalysis

Porous layered carbon nanomaterials play important role in the efficient loading of electroactive substances for high performance energy conversion techniques. Herein, an intramolecular cyclization induced self-assembly (ICISA) strategy is proposed to prepare three-dimensional highly porous layered carbon nanostructures (LCs) for efficient loading of various transition metal nanoparticles for oxygen reduction reaction (ORR) catalysis. The amphiphilic alternating copolymer poly(amic acid) (PAA) is synthesized by the stepwise polymerization of hydrazine hydrate and pyromellitic dianhydride. Upon heating above 160 °C, the intramolecular cyclization reaction occurs, leading to the formation of rigid, crystalline and non-soluble polyimide segments in the backbone, which induces the self-assembly of the polymer to form dumbbell-shaped assemblies with a high solid content of 15%. After pyrolysis in a nitrogen atmosphere, LCs are obtained. Cobalt (Co), iron (Fe) and FeCo nanoparticles can be efficiently loaded, noted as Co@LCs, Fe@LCs and FeCo@LCs, respectively. The ORR catalytic performance of the catalysts is evaluated to give half wave potentials of 0.791, 0.787 and 0.812 V, and limit current densities of 4.92, 4.73 and 4.71 mA cm−2 for Co@LCs, Fe@LCs and FeCo@LCs, respectively. Overall, we propose an ICISA strategy to facilely prepare three-dimensional carbon nanomaterials with highly porous layered structure for efficient ORR catalysis.

Controlled and restricted growth of cobalt nanoparticles embedded in ordered mesoporous carbons @ carbon nanotubes for metronidazole electrochemical biosensing study

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Nano particle distribution in blood via electroosmotic peristaltic flow in a non-uniform wavy membrane base capillaries

ObjectiveThe primary purpose of this article is to undertake a mathematical investigation into the electro osmotically thermally driven transport of solute particles, which are typically on a micro to nano-meter scale, suspended in blood. The study is conducted within a non-uniform porous channel for a Williamson fluid. The main objective of this research is to explore the interactions and consequences of solute particles and nanoparticles in the Esophagus, particularly regarding their potential applications in drug delivery and biomedical engineering, especially in the context of electroosmotic non-Newtonian fluids. SignificanceThis research also has significant implications for microscale physiological phenomena. In this investigation, blood serves as the base fluid, and a nanofluid is created by introducing Nickel and Cobalt nanoparticles into the blood. Both nanoparticles have critical medical applications, especially in drug delivery and cancer treatment. To delve deeper into the study of nanomedicine delivery, Nickel and Cobalt nanoparticles are introduced into the blood alongside other smaller solute particles. MethodologyThe mathematical modeling is conducted in a rectangular coordinate system, and the governing flow equations are linearized using approximations that consider low Reynolds numbers and large wavelengths. The numerical solution is computed for a coupled set of nonlinear equations that describe the profiles of fluid-particle velocity, temperature, and fluid-particle composition. The study explores the influence of various key parameters and presents these effects through graphical representations. FindingsIt is observed that an increase in the suspension concentration and the Williamson fluid parameter leads to higher fluid velocity, while the temperature distribution exhibits the opposite trend. The introduction of nanoparticles into the fluid decelerates the flow and raises the temperature.

Cobalt nanoparticles confined nitrogen–doped carbon integrated bimetallic Co2P–VP heterostructured composite: A MOF integrated 3D arrays for catalytic water splitting

A robust electrode material with outstanding stability at high current density is crucial for the practical application of water splitting. We present an intertwined heterostructure composed of in-situ confined cobalt nanoparticles (Conp) in nitrogen-doped carbon (N–C), derived from functionalized zeolitic imidazolate framework–67 (ZIF−67), and composited with the hetero phase bimetallic cobalt vanadium phosphide (Co2P−VP) through a hydrothermal reaction, room temperature aging, and chemical vapor deposition (CVD) for simultaneous phosphidation, graphitization, and reduction. The synergistic effect generated across the multiple heterointerfaces of Co2P, VP, and Conp in the N−doped carbon on nickel foam, as the Co2P–VP@N–C/Co heterostructure, exhibits outstanding electrocatalytic performance for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and electrochemical water splitting. The Co2P–VP@N–C/Co (+,−) alkaline electrolyzer demonstrates a low potential of 1.49 and 1.71 V to achieve current densities of 10 and 100 mA cm−2, respectively. It exhibits outstanding stability during continuous operation for 100 h at 100 mA cm−2, with 98.02 % retention. The outstanding performance is credited to the synergistic interaction and d-electronic modulation of the metallic hetero phasic Co2P–VP moiety and confined Conp in a functionalized N−doped porous carbonaceous heterostructure. Density Functional Theory (DFT) validates the regulation of electronic structure for efficient redistribution of local charges and electron transfer.

Microwave driven steam reforming of biomass model tar based on metal organic frameworks (ZIF-67) derived Co/C catalyst

Tar catalytic removal is a key issue in biomass gasification, which is suffering from catalyst coking and sintering. Microwave technology is attractive due to the high activity on polar molecules and ability to lower activation energy. In this study, the Co/C derived from metal-organic frameworks (ZIF-67) was developed as a bifunctional microwave catalyst that can strengthen the interaction between microwave and tar catalytic reforming, and enhance the anti-coking and sintering ability. The effects of the temperature, heating method, tar concentration, and catalyst support on model tar conversion rate were investigated. The operating conditions at 700 °C and tar concentration lower than 20 g/m3 can reach a promising conversion rate over 90.15 % under microwave irradiation. On the one hand, microwave heating groups performed better in conversion rate and coking compared to conventional heating, due to the active species generated from the microwave plasma. On the other hand, Co/C showed better performance in catalytic activity and sintering stability, due to the highly dispersion of cobalt nanoparticles and the confinement effect of carbon nanotubes on the catalyst surface. These findings proposed a novel approach for efficient biomass tar removal under microwave irradiation, and offered a potential tool to further reveal the mechanism in microwave driven tar steam reforming system.

Nitrogen-functionalized catalyst synthesized using spent coffee ground biochar-cobalt hybrid for oxygen reduction reaction via pyrolysis and ball-milling

In this work, oxygen reduction reaction (ORR) catalysts were developed from a precursor of spent coffee ground-based biochar. Nitrogen doping was achieved via urea addition preceding a pyrolysis synthesis process, yielding nitrogen-doped biochar (NDB). Cobalt was deposited onto the NDB surface using a non-conventional ball-milling procedure. The microstructure of the synthesized samples was studied through Scanning Electron Microscopy (SEM), where a rather distorted surface, highlighted by prominent wrinkles (which doubled the surface area at 50.58 m2/g), was shown for nitrogen-doped samples. Moreover, the high energy ball-milling technique shows an almost perfect coverage of cobalt nanoparticles on the biochar surface through SEM/EDS and Raman results. Additionally, electrochemical testing was conducted using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry measurements conducted under nitrogen (inert) and oxygen-saturated alkaline solution (0.1 M KOH) conditions showed that nitrogen doping enhances the oxygen reduction reaction current (-1 vs -0.59 mA.cm−1 at -0.3 V vs Hg/HgO) and slightly reduces the onset potential compared to pristine biochar. Depositing cobalt onto the NDB surface had a minor adverse effect on the onset potential, but significantly increased the oxygen reduction reaction current, reaching a value of -2.09 mA.cm−2 at -0.3 V vs Hg/HgO. All catalysts were compared to a commercial carbon supported platinum catalyst (Pt10%C) to showcase the potential room of improvement for the developed catalysts.

Machine learning powered CN-coordinated cobalt nanoparticles embedded cellulosic nanofibers to assess meat quality via clenbuterol monitoring

The World Anti-Doping Agency (WADA) has prohibited the use of clenbuterol (CLN) because it induces anabolic muscle growth while potentially causing adverse effects such as palpitations, anxiety, and muscle tremors. Thus, it is vital to assess meat quality because, athletes might have positive test for CLN even after consuming very low quantity of CLN contaminated meat. Numerous materials applied for CLN monitoring faced potential challenges like sluggish ion transport, non-uniform ion/molecule movement, and inadequate electrode surface binding. To overcome these shortcomings, herein we engineered bimetallic zeolitic imidazole framework (BM-ZIF) derived N-doped porous carbon embedded Co nanoparticles (CN-CoNPs), dispersed on conductive cellulose acetate-polyaniline (CP) electrospun nanofibers for sensitive electrochemical monitoring of CLN. Interestingly, the smartly designed CN-CoNPs wrapped CP (CN-CoNPs-CP) electrospun nanofibers offers rapid diffusion of CLN molecules to the sensing interface through amine and imine groups of CP, thus minimizing the inhomogeneous ion transportation and inadequate electrode surface binding. Additionally, to synchronize experiments, machine learning (ML) algorithms were applied to optimize, predict, and validate voltametric current responses. The ML-trained sensor demonstrated high selectivity, even amidst interfering substances, with notable sensitivity (4.7527 μA/μM/cm2), a broad linear range (0.002–8 μM), and a low limit of detection (1.14 nM). Furthermore, the electrode exhibited robust stability, retaining 98.07% of its initial current over a 12-h period. This ML-powered sensing approach was successfully employed to evaluate meat quality in terms of CLN level. To the best of our knowledge, this is the first study of using ML powered system for electrochemical sensing of CLN.

Controllable fiberization engineering of cobalt anchored mesoporous hollow carbon spheres for positive feedback to electromagnetic wave absorption

In order to overcome the limitations of single attenuation mechanism materials in effectively absorbing electromagnetic waves (EMW), meticulous microstructural design of composites and an elevated degree of integration of wave absorbing mechanisms are crucial. Utilizing mesoporous hollow carbon spheres as precursors, PCHM@ComXn (X = Se, S, O) nano-microspheres were synthesized by anchoring cobalt nanoparticles on the surface, controllable encapsulating in continuous fiber structure by electrostatic spinning technique subsequently. The carbon shell-cavity core configuration interspersed with nanoparticles has the advantage of light weight, low density and extensive defects. Abundant heterogeneous interface in carbon fiber offers excellent electrical conductivity and high specific surface area, while a three-dimension conductive network optimizes the transmission loss to incident EMW. The efficient synergy of multiple mechanisms enables PCHM@CoSe2/CNFs to achieve a strong reflection loss of −50.55 dB at a matched thickness of 2.0 mm, while the EABmax value can be extended to a remarkable 6.80 GHz at 2.3 mm, which is considerably superior to fiber samples encapsulating other cobalt-based nanoparticles of the same family. This work provides an innovative direction for the development of high-performance EMW absorbers.

Co/CoO nanoparticles loaded on multi-walled carbon Nanotubes@Covalent organic frameworks for electrocatalytic hydrogen evolution

Producing hydrogen by electrolyzing water has received increased attention. Nevertheless, a major challenge remains in the search for high performance hydrogen evolution reaction (HER) electrocatalysts. In this work, multi-walled carbon nanotubes (MWCNTs) capped by TpPa covalent organic framework (TpPa-COF) react with cobalt nitrate hexahydrate (Co(NO3)2·6H2O) to form a novel ternary one-body complex (MWCNTs@TpPa-COF@Co/CoO). Wherein, TpPa-COF is constructed from 2,4,6-Triformylphloroglucinol (Tp) and p-phenylenediamine (Pa) as structural units. This COF is relatively inexpensive, provides more coordination sites for metal loading, and is particularly stable in acidic and basic media. The results show that the composite material has high electrocatalytic HER activity in a potassium hydroxide (KOH) condition with an overpotential value of 28.8 mV and a Tafel slope of 69.07 mV dec−1 at a current density of 10 mA cm−2. Meanwhile, the MWCNTs@TpPa-COF@Co/CoO showed excellent stability after 2000 cycles in alkaline media. The characterization demonstrated that the material provided low resistance during the charge transfer process, which resulted in improved electrochemical performance. In addition, the COF loaded with cobalt nanoparticles provided more active sites for the reaction. Thus, the synthesized MWCNTs@TpPa-COF@Co/CoO emerges turns out to be a Pt-free, stable and efficient HER electrocatalyst, holding significant promise for practical applications.

Spectroscopic and antibacterial activities of cobalt and nickel nanoparticles: a comparative analysis

This study aimed to compare the spectroscopy, morphological, electrocatalytic properties, and antibacterial activities of cobalt nanoparticles (CoNPs) with nickel nanoparticles (NiNPs). Cobalt nanoparticles and NiNPs were prepared via a chemical reduction approach and characterized utilizing transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD) techniques. The result from XRD and TEM analysis revealed that the synthesized nanoparticles exhibit face-centered cubic with smooth spherical shape, having average particles size of 12 nm (NiNPs) and 18 nm (CoNPs). The electrochemical properties of the nanoparticles were examined via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The CV results showed that GCE-Ni (35.6 μA) has a higher current response compared to GCE-Co (10.5 μA). The EIS analysis revealed that GCE-Ni (1.39 KΩ) has faster electron transport capability compared to GCE-Co (2.99 KΩ) as indicated in their Rct values. The power density of the synthesized nanoparticles was obtained from their "knee" frequency (f°) values, with GCE-Ni (3.16 Hz) having higher f° values compared to GCE-Co (2.00 Hz). The antibacterial activity of the nanoparticles was evaluated against multidrug-resistant Escherichia coli O157, Escherichia coli O177, Salmonella enterica, Staphylococcus aureus, and Vibrio cholerae. The result from the antibacterial study revealed that at low concentrations both CoNPs and NiNPs have significant antibacterial activities against E. coli O157, E. coli O177, S. enterica, S. aureus, and V. cholerae. NiNPs showed better antibacterial activities at low concentrations of 61.5, 61.5, 125, 61.5, and 125 µg/mL compared to CoNPs with minimum inhibitory concentrations of 125, 125, 250, 61.5, and 125 µg/mL against E. coli O157, E. coli O177, S. enterica, S. aureus, and V. cholerae, respectively. These promising antibacterial activities emphasize the potential of CoNPs and NiNPs as effective antibacterial agents, which could aid in the development of novel antibacterial medicines.

A recyclable and durable magnetic cobalt nanoparticle-embedded mesoporous graphene nanohybrid for removal of pollutants from aqueous media

Cobalt nanoparticles (Co NPs) embedded in mesoporous graphene (MG) were prepared via a hydrothermal reaction followed by carbothermal reduction in an argon atmosphere. This cobalt nanoparticle-embedded mesoporous graphene (CoMG) was systematically investigated for structural, morphological, and magnetic properties before and after 10 successive cycles of adsorption and regeneration, using methylene blue (MB) dye as a model pollutant. The CoMG nanohybrid has a superior specific surface area of 807 m2 g−1, with a significant mesopore volume of 1.63 cm3 g−1 that allows fast and high pollutant removal efficiency of ∼84 % within 30 min as well as the maximum adsorption capacity of 178.6 mg g−1 with MB solution of 100 mg L−1, which is well described with pseudo-second-order adsorption kinetics. The consecutive adsorption−regeneration experiments revealed that the CoMG nanohybrid retained more than half of the initial dye removal efficiency even after being reused 10 times. After the tenth cycle, the regenerated CoMG maintained a high specific area of 688 m2 g−1 and a large mesopore volume of 1.51 cm3 g−1, indicating the long-lasting porous structure of the CoMG nanohybrid. The metallic cobalt phase and ferromagnetic nature of the Co NPs in the nanohybrid are retained because of the host MG, which prevents nanoparticle aggregation and serves as a protective environment for the embedded Co NPs in aqueous media during the adsorption−regeneration cycle tests of the adsorbent. The experimental results demonstrate that the CoMG nanohybrid has superior pollutant removal capacity and maintains more than half of the initial efficiency even after 10 cycles of use, making it a cost-efficient and energy-saving material for the removal of organic pollutants from aqueous media and in other environmental applications.

Si nanoparticles enclosed in hierarchically structured dual-component porous carbon as superior anode for lithium-ion batteries: Structure formation and properties investigation

The volume effect of Si hinders its application as anode for lithium-ion batteries. To address these challenges, composites consisting of Si nanoparticles enclosed in a hierarchically structured carbon matrix are constructed. Firstly, Si nanoparticles are embedded in the metal-organic framework of ZIF-67 with a surface modification directed epitaxial growth. Subsequently, the Si embedded ZIF-67 are further integrated into microspheres of polysaccharide using spray drying, achieving encapsulation of the Si nanoparticles in a hierarchically structured carbon sphere after calcination. Metallic cobalt nanoparticles are derived from the decomposition of ZIF-67, which act as a catalyst and facilitate in turn the decomposition of the organic ligands along with the extensive growth of carbon nanotubes (CNTs). The CNTs formed in-situ act as reinforcing and conductive networks, providing the compact and robust interfaces between the Si and the carbon matrix. The dual-component carbon substrates induce a thinner and inorganic carbonate-rich solid electrolyte interface (SEI) during cycling. The novel structure endows the composite a specific capacity of 1018 mAh g−1 after 1200 cycles at a current density of 1000 mA g−1 for half-cell and exhibits a high capacity retention rate of 76.9 % after 200 cycles for full cell paired with lithium iron phosphate as cathode.