Search Results (128)

Composites of ferromagnetic and ferroelectric phases are of interest for studies on mechanical strain-mediated coupling between the two phases and for a variety of applications in sensors, energy harvesting, and high-frequency devices. Nanocomposites are of particular importance since their surface area-to-volume ratio, a key factor that determines the strength of magneto-electric (ME) coupling, is much higher than for bulk or thin-film composites. Core–shell nano- and microcomposites of the ferroic phases are the preferred structures, since they are free of any clamping due to substrates that are present in nanobilayers or nanopillars on a substrate. This review concerns recent efforts on ME coupling in coaxial fibers of spinel or hexagonal ferrites for the magnetic phase and PZT or barium titanate for the ferroelectric phase. Several recent studies on the synthesis and ME measurements of fibers with nickel ferrite, nickel zinc ferrite, or cobalt ferrite for the spinel ferrite and M-, Y-, and W-types for the hexagonal ferrites were considered. Fibers synthesized by electrospinning were found to be free of impurity phases and had uniform core and shell structures. Piezo force microscopy (PFM) and scanning microwave microscopy (SMM) measurements of strengths of direct and converse ME effects on individual fibers showed evidence for strong coupling. Results of low-frequency ME voltage coefficient and magneto-dielectric effects on 2D and 3D films of the fibers assembled in a magnetic field, however, were indicative of ME couplings that were weaker than in bulk or thick-film composites. A strong ME interaction was only evident from data on magnetic field-induced variations in the remnant ferroelectric polarization in the discs of the fibers. Follow-up efforts aimed at further enhancement in the strengths of ME coupling in core–shell composites are also discussed in this review. Full article

Organophosphorus pesticides (OPs), while pivotal for agricultural productivity, pose severe environmental and health risks due to their persistence and bioaccumulation. Existing detection methods, such as chromatography and spectroscopy, face limitations in field adaptability, cost, and operational complexity. To address these challenges, this study introduces a novel dual-mode photoelectrochemical–electrochemical (PEC-EC) sensor based on a Co,N-TiO₂@ZrO₂/3DGH nanocomposite. The sensor synergistically integrates zirconium oxide (ZrO₂) for selective OP capture via phosphate-Zr coordination, cobalt-nitrogen co-doped titanium dioxide (Co,N-TiO₂) for visible-light responsiveness, and a three-dimensional graphene hydrogel (3DGH) for enhanced conductivity. In the PEC mode under light irradiation, OP adsorption induces charge recombination, yielding a logarithmic photocurrent attenuation with a detection limit of 0.058 ng mL⁻¹. Subsequently, the EC mode via square wave voltammetry (SWV) self-validates the results, achieving a detection limit of 0.716 ng mL⁻¹. The dual-mode system demonstrates exceptional reproducibility, long-term stability, and selectivity against common interferents. Parallel measurements revealed <5% inter-mode discrepancy, validating the intrinsic self-checking capability. This portable platform bridges the gap between laboratory-grade accuracy and field-deployable simplicity, offering transformative potential for environmental monitoring and food safety management. Full article

Magnetoelectric composites enable strain-mediated coupling between magnetic and electric fields, supporting applications in sensors, actuators, and tunable devices. This study presents a finite element modeling framework for simulating the direct magnetoelectric effect in core–shell and layered nanocomposites fabricated by material jetting (inkjet printing). The model incorporates nonlinear magnetostrictive behavior of cobalt ferrite nanoparticles and size-dependent piezoelectric properties of barium titanate, allowing efficient simulation of complex interfacial strain transfer. Results show a strong dependence of coupling on field orientation, particle arrangement, and interfacial geometry. Simulations of printed droplet geometries, including coffee ring droplet morphologies, reveal enhanced performance through increased surface area and directional alignment. These findings highlight the potential of material jetting for customizable, high-performance magnetoelectric devices and provide a foundation for simulation-guided design. Full article

A highly redox-active ternary nickel sulfide and cobalt-anchored carbon nanocomposite (NiS-Co@C) electrochemical electrode is synthesized by a two-step pyrolysis-hydrothermal method using biomass-derived carbon. The high-crystalline hierarchical porous nanostructure provides abundant voids and cavities, along with a large specific surface area, to improve the interfacial properties. The as-synthesized electrode achieved a specific capacity of 640 C g⁻¹ at 1 A g⁻¹, with a capacity retention of 93% over 5000 cycles, revealing outstanding electrochemical properties. Nickel sulfide nanoparticles embedded in the cobalt-anchored carbon framework improved redox activity, ion transport, and conductivity, resulting in a dominant diffusion-controlled battery-type behavior. Moreover, a hybrid supercapattery, based on battery-type NiS-Co@C as the positrode and capacitive-type activated carbon as the negatrode, achieved a maximum specific energy/power of 33 Wh kg⁻¹/7.1 kW kg⁻¹ with a 91% capacity retention after 5000 cycles. The synergistic effect of the combinatorial battery–capacitor behavior of the hybrid supercapattery has improved the specific energy–power considerably, leading the development of next-generation energy storage technologies. Full article

Nanoparticles (NPs) have generated significant interest in various fields due to the unique properties that materials exhibit at the nanoscale. This study presents a comparative analysis of copper nanoparticles (Cu-NPs) and cobalt nanoparticles (Co-NPs) synthesized via conventional solvothermal and green hydrothermal synthesis using ethylene glycol and Medicago sativa extract, respectively. The conventional solvothermal synthesis showed higher efficiency for both Cu-NPs and Co-NPs with yields of 32.5% and 26.7%, respectively. Characterization through UV–visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) revealed that while solvothermal synthesis produced larger particles (76.5 nm for Cu-NPs, 86.8 nm for Co-NPs), the green hydrothermal method yielded smaller particles (53.8 nm for Cu-NPs, 67.7 nm for Co-NPs) with better control over particle size distribution and spherical morphology, showing minimal agglomeration. UV–vis confirmed metal oxide formation, while FTIR showed complex patterns in NPs (green hydrothermal), indicating plant extract compounds. Antifungal evaluation against Pseudocercospora fijiensis showed complete inhibition at 2000 ppm for both NP types, with no mycelial growth after 30 days. When integrated into chitosan, solvothermal NPs produced rougher surfaces, and scanning electron microscope (SEM) confirmed the presence of copper and cobalt in the nanocomposites. This study provides insights into the synthesis of nanoparticles using an environmentally friendly process and their microbiological applications for future use in organic agriculture. Full article

In the field of non-silicon MEMSs (micro-electro-mechanical systems), nickel, with its mature preparation method, good compatibility with non-silicon MEMS processes, and excellent mechanical properties, is one of the commonly used structural materials. By effectively combining it with non-silicon MEMS processes, nickel is widely used in typical process systems such as LIGA (Lithography, Galvanoformung, Abformung)/UV-LIGA (Ultraviolet Lithography, Galvanoformung, Abformung). However, with the rapid development of the non-silicon MEMS field, pure nickel materials are no longer able to meet current material demands. Alternatively, nickel–cobalt composite materials have excellent mechanical properties, thermal stability, corrosion resistance, and good adaptability to processing technology because cobalt has unique advantages as a reinforcing phase, including excellent wear resistance, corrosion resistance, and high hardness. This article examines the current methods for preparing nickel–cobalt alloys by focusing on composite electrodeposition of coatings and analyzing their advantages and disadvantages. Based on this, the effect of the composite electrodeposition conditions on the formation mechanism of nickel–cobalt alloy coatings is discussed. Then, the research status of composite electrodeposition methods mainly based on nickel–cobalt nanocomposites is discussed. Finally, a new direction for future work on nickel–cobalt composite materials mainly composed of nickel–cobalt nanomaterials prepared by composite electrodeposition is proposed, and its application prospects in non-silicon MEMS fields are discussed. Full article

The purpose of this work was to consider the decolorization efficiency of reactive yellow 160 (Ry-160) dye utilizing cobalt aluminum oxide (AlCo₂O₄)-anchored Multi-Walled Carbon Nanotubes (AlCo₂O₄/MWCNTs) nanocomposites as catalysts for the first time in a photocatalytic process under natural sunlight irradiation. The compositional, morphological, and functional group analyses of AlCo₂O₄ and AlCo₂O₄/MWCNTs were performed by utilizing Energy Dispersive Spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FE-SEM), and Fourier Transform Infrared (FTIR) Spectroscopy, respectively. A UV-Vis (UV-Vis) spectrophotometer was used to investigate degradation efficiency. The results exhibited a reduction in the optical bandgap for AlCo₂O₄/MWCNTs nanocomposites as catalysts from 1.5 to 1.3 eV compared with pure spinel AlCo₂O₄ nanocomposites. AlCo₂O₄/MWCNTs nanocomposites showed excellent photocatalytic behavior, and around 96% degradation of Ry-160 dye was observed in just 20 min under natural sunlight, showing first-order kinetics with rate constant of 0.151 min⁻¹. The results exhibited outstanding stability and reusability for AlCo₂O₄/MWCNTs by maintaining more than 90% photocatalytic efficiency even after seven successive operational cycles. The betterment of the photocatalytic behavior of AlCo₂O₄/MWCNTs nanocomposites as compared to AlCo₂O₄ nanocomposites owes to the first-rate storage capacity of electrons in MWCNTs, due to which the catalyst became an excellent electron acceptor. Furthermore, the permeable structure of MWCNTs results in a greater surface area leading to the onset of more active sites, and, in turn, it also boosts conductivity and reduces the formation of agglomerates on the surface of catalysts, which inhibits e−/h⁺ pair recombination. Concisely, the synthesis of a novel AlCo₂O₄/MWCNTs catalyst with excellent and fast photocatalytic activity was the aim of this study. Full article

Research into the introduction of alloying and reinforcing nanocomposites into nickel (Ni) coatings has been motivated by the need for tribologically superior coatings that will improve energy efficiency. Using pulse electrodeposition, this work investigates the effects of adding cobalt (Co) as the alloying nanoparticle and silicon carbide (SiC), zirconium oxide (ZrO₂), and aluminium oxide (Al₂O₃) as reinforcing nanocomposites to Ni coatings. The surface properties, mechanical strength, nanotribological behaviour, and wettability of these coatings were analysed. Surface characteristics were evaluated by the use of a Scanning Electron Microscope, revealing a grain dimension reduction of approximately ~7–43% compared to pristine Ni coatings. When alloying and reinforcing nanocomposites were added to Ni coatings, nanoindentation research showed that there was an increase in nanohardness of ~12% to ~69%. This resulted in an improvement in the tribological performance from approximately 2% to 65%.The hydrophilic nature of Ni coatings was observed with wettability analysis. This study demonstrates that nanocomposite reinforcement can be used to customise Ni coatings for applications that require exceptional tribological performance. The results point to the use of Ni-Co coatings for electronics and aerospace sectors, with more improvements possible with the addition of reinforcing nanoparticles. Full article

This paper reviews recent advances in the synthesis of cobalt-free high-strength tungsten carbide (WC) composites as sustainable alternatives to conventional WC-Co composites. Due to the high cost of cobalt, limited supply, and environmental concerns, researchers are exploring nickel, iron, ceramic binders, and nanocomposites to obtain similar or superior mechanical properties. Various synthesis methods such as powder metallurgy, encapsulation, 3D printing, and spark plasma sintering (SPS) are discussed, with SPS standing out for its effectiveness in densifying and preventing WC grain growth. The results show that cobalt-free composites exhibit high strength, wear and corrosion resistance, and harsh environment stability, making them viable competitors for WC-Co materials. The use of nickel and iron with SPS is shown to enable the development of environmentally friendly, cost-effective materials. It is emphasized that microstructural control and phase management during sintering are critical to improve a material’s properties. The application potential of these composites covers mechanical engineering, metallurgy, oil and gas, and aerospace, emphasizing their broad industrial relevance. Full article

In this paper, a novel, cost-effective, and green methodology has been investigated for the preparation of cobalt (II) nanoparticles supported on a nanodiamond-carbon-structure grafted polyethyleneimine@folic acid (ND-g-PEI@FA@Co(II)) nanocomposite. Some of the physicochemical characteristics of the synthesized efficient heterogeneous nanocatalyst, including bond formation and functional groups, percentage of elements, crystalline phase, and surface morphology were studied using techniques such as Fourier transform infrared spectroscopy (FT-IR), Energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). Following the principles of green chemistry, this nanocatalyst has been used in the production of 5-substituted 1H-tetrazole derivatives using different benzaldehyde derivatives, sodium azide, and malononitrile agents in ethanol eco-friendly solvent with high efficiency. The mechanism of tetrazole synthesis is carried out through cascade condensations, such as Knoevenagel condensation, 1,3-dipolar cycloaddition, and tautomerization reactions. The main advantages of the ND-g-PEI@FA@Co(II) nanocatalyst include facile preparation, easy separation, minimal consumption of catalyst for a multicomponent reaction (MCR), the use of cheap and recyclable materials, excellent product yield, and reusability up to four times with good efficiency. The substrate used in this heterogeneous catalyst (ND) with appropriate thermal stability, abundant availability in large quantities, and non-toxicity are prominent features of the synthesized nanocomposite. Full article

Thiosemicarbazone (TSC) derivatives and their complexes have emerged as versatile medicinal agents. Now, the focus has shifted to targeted drug delivery and here, the application of nanotechnology is being explored. Nanoparticles (NP) are being explored owing to their tremendous medicinal applications. They are also known to overcome the water insolubility of medicinal agents and have the ability to target specific targets. This article aims to explore the fabrication strategies and applications of functionalized TSCs conjugated with NPs for improved therapeutic potential. The studies were taken from the recent literature and indexed in leading databases. The literature survey reveals the fabrication of TSCs with chitosan-coated superparamagnetic magnetite NPs, which showed significant anti-proliferative activity against several cell lines. Similarly, cobalt oxide nanoparticles conjugated with TSCs have been tested against the hepatic cancer cell line HepG2. Other than anticancer activity, the functionalized nanoparticles have also been employed against drug-resistant pathogens. To improve the oral bioavailability and pharmacological activity, nanoparticle-based block polymers have been proposed to encapsulate the TSC moiety. The in vitro activity of the fabricated NPs has been tested against Leishmania amazonensis. Against microphages, less cytotoxicity was observed. The article may shed light on the structure–bioactivity relationship of novel nanocomposites derived from TSCs and NPs and their specific mechanisms of action. Full article

Currently, there is an increasing need to find new ways to purify water by eliminating bacterial biofilms, textile dyes, and toxic water pollutants. These contaminants pose significant risks to both human health and the environment. To address this issue, in this study, we have developed an eco-friendly approach that involves synthesizing a cobalt-doped cerium iron oxide (CCIO) nanocomposite (NC) using an aqueous extract of Gossypium arboreum L. stalks. The resulting nanoparticles can be used to effectively purify water and tackle the challenges associated with these harmful pollutants. Nanoparticles excel in water pollutant removal by providing a high surface area for efficient adsorption, versatile design for the simultaneous removal of multiple contaminants, catalytic properties for organic pollutant degradation, and magnetic features for easy separation, offering cost-effective and sustainable water treatment solutions. A CCIO nanocomposite was synthesized via a green co-precipitation method utilizing biomolecules and co-enzymes extracted from the aqueous solution of Gossypium arboreum L. stalk. This single-step synthesis process was accomplished within a 5-h reaction period. Furthermore, the synthesis of nanocomposites was confirmed by various characterization techniques such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and energy dispersive X-ray (EDX) technology. CCIO NCs were discovered to have a spherical shape and an average size of 40 nm. Based on DLS zeta potential analysis, CCIO NCs were found to be anionic. CCIO NCs also showed significant antimicrobial and antioxidant activity. Overall, considering their physical and chemical properties, the application of CCIO NCs for the adsorption of various dyes (~91%) and water pollutants (chromium = ~60%) has been considered here since they exhibit great adsorption capacity owing to their microporous structure, and represent a step forward in water purification. Full article

Two-dimensional (2D) sulfide-based transition metal dichalcogenides (TMDs) have shown their crucial importance in energy storage devices. In this study, the tungsten disulfide (WS₂) nanosheets were combined with hydrothermally synthesized cobalt magnesium sulfide (CoMgS) nanocomposite for use as efficient electrodes in supercapattery energy storage devices. The characteristics of the WS₂@CoMgS nanocomposite were better than those of the WS₂ and CoMgS electrodes. XRD, SEM, and BET analyses were performed on the nanocomposite to examine its structure, morphology, and surface area in depth. In three-electrode assemblies, the composite (WS₂@CoMgS) electrode showed a high specific capacity of 874.39 C g⁻¹ or 1457.31 F g⁻¹ at 1.5 A g⁻¹. The supercapattery device (WS₂@CoMgS//AC) electrode demonstrated a specific capacity of 325 C g⁻¹ with an exceptional rate capability retention of 91% and columbic efficiency of 92% over 7000 cycles, according to electrochemical studies. Additionally, the high energy storage capacity of the WS₂@CoMgS composite electrode was proved by structural and morphological investigations. Full article

Transition metal oxides are a great alternative to less expensive hydrogen evolution reaction (HER) catalysts. However, the lack of conductivity of these materials requires a conductor material to support them and improve the activity toward HER. On the other hand, carbon paste electrodes result in a versatile and cheap electrode with good activity and conductivity in electrocatalytic hydrogen production, especially when the carbonaceous material is agglomerated with ionic liquids. In the present work, an electrode composed of multi-walled carbon nanotubes (MWCNTs) and cobalt ferrite oxide (CoFe₂O₄) was prepared. These compounds were included on an electrode agglomerated with the ionic liquid N-octylpyridinium hexafluorophosphate (IL) to obtain the modified CoFe₂O₄/MWCNTs/IL nanocomposite electrode. To evaluate the behavior of each metal of the bimetallic oxide, this compound was compared to the behavior of MWCNTs/IL where a single monometallic iron or cobalt oxides were included (i.e., α-Fe₂O₃/MWCNTs/IL and Co₃O₄/MWCNTs/IL). The synthesis of the oxides has been characterized by X-ray diffraction (XRD), RAMAN spectroscopy, and field emission scanning electronic microscopy (FE-SEM), corroborating the nanometric character and the structure of the compounds. The CoFe₂O₄/MWCNTs/IL nanocomposite system presents excellent electrocatalytic activity toward HER with an onset potential of −270 mV vs. RHE, evidencing an increase in activity compared to monometallic oxides and exhibiting onset potentials of −530 mV and −540 mV for α-Fe₂O₃/MWCNTs/IL and Co₃O₄/MWCNTs/IL, respectively. Finally, the system studied presents excellent stability during the 5 h of electrolysis, producing 132 μmol cm⁻² h⁻¹ of hydrogen gas. Full article

The rapid development of the battery industry has brought about a large amount of waste battery pollution. How to realize the high-value utilization of waste batteries is an urgent problem to be solved. Herein, cobalt and titanium compounds (LTCO) were firstly recovered from spent lithium-ion batteries (LIBs) using the carbon thermal reduction approach, and plasmonic attapulgite/Co(Ti)Ox (H-ATP/Co(Ti)Ox) nanocomposites were prepared by the microwave hydrothermal technique. H-ATP had a large specific surface area and enough active sites to capture CO₂ molecules. The biochar not only reduced the spinel phase of waste LIBs into metal oxides including Co₃O₄ and TiO₂ but also increased the separation and transmission of the carriers, thereby accelerating the adsorption and reduction of CO₂. In addition, H-ATP/Co(Ti)Ox exhibited a localized surface plasmon resonance effect (LSPR) in the visible to near-infrared region and released high-energy hot electrons, enhancing the surface temperature of the catalyst and further improving the catalytic reduction of CO₂ with a high CO yield of 14.7 μmol·g⁻¹·h⁻¹. The current work demonstrates the potential for CO₂ reduction by taking advantage of natural mineral and spent batteries. Full article