Cobalt nanofibers coated with layered nickel silicate coaxial core-shell composites as excellent anode materials for lithium ion batteries

A renewable screen-printed electrode based on magnetic NiCo@N-doped carbon nanotubes derived from Co-MOF for ractopamine detection

A renewable electrochemical screen-printed electrode (SPE) is proposed based on magnetic bamboo-like nitrogen-carbon (N-C) nanotubes loaded with nickel-cobalt alloy (NiCo) nanoparticles (NiCo@N-CNTs) for the determination of ractopamine (RAC). During the preparation of NiCo@N-CNTs, Co-MOF-67 (ZIF-67) was firstly synthesized, and then blended with dicyandiamide and nickel acetate, followed by a one-step pyrolysis procedure to prepare NiCo@N-doped carbon nanotubes. The surface morphology, structure, and chemical composition of NiCo@N-CNTs were characterized by SEM, TEM, XRD, XPS, and EDS. The electrocatalytic and electrochemical behavior of NiCo@N-CNTs were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that NiCo@N-CNTs possessed remarkable conductivity and electrocatalysis to the oxidation of ractopamine (RAC). By using screen-printed electrode (SPE), NiCo@N-CNTs, and a designed base support, a magnetic RAC sensor (NiCo@N-CNTs/SPE) was successfully constructed. It presented a detection linear range of 0.05-80 μM with a detection limit of 12 nM (S/N = 3). It also exhibited good sensitivity, reproducibility, and practicability in spiked real pork samples. Since the adhesion of NiCo/N-CNTs on SPE was controlled by magnet, the NiCo@N-CNTs was easily detached from the SPE surface by magnetism and thus displayed excellent renewability. This work broadened insights into portable devices for on-site and real-time analysis.

Research progress and future perspectives on electromagnetic wave absorption of fibrous materials

Electromagnetic waves have caused great harm to military safety, high-frequency electronic components, and precision instruments, and so forth, which urgently requires the development of lightweight, high-efficiency, broadband electromagnetic waves (EMW) absorbing materials for protection. As the basic fibrous materials, carbon fibers (CFs) and SiC fibers (SiCf) have been widely applied in EMW absorption due to their intrinsic characteristics of low density, high mechanical properties, high conductivity, and dielectric loss mechanism. Nevertheless, it has remained a great challenge to develop lightweight EMW-absorbing fibrous materials with strong absorption capability and broad frequency range. In this review, the fundamental electromagnetic attenuation mechanisms are firstly introduced. Furthermore, the preparation, structure, morphology, and absorbing performance of CFs and SiCf-based EMW absorbing composites are summarized. In addition, prospective research opportunities are highlighted toward the development of fibrous absorbing materials with the excellent absorption performance.

Ecofriendly synthesis and characterization of Ni2+ codoped silica magnesium zirconium copper nanoceramics for wastewater treatment applications

This article investigates the effect of Ni²⁺ content on structural (XRD, XPS), morphological (TEM), and magnetic behaviors of silica magnesium zirconium copper nanoceramics calcined at 800 °C. The sol–gel route is followed for the silica magnesium zirconium copper/(0.0–0.7) Ni²⁺ samples preparation. X-ray photoelectron spectroscopy is employed to analyze the chemical states of elements for the samples. The three representative binding energy magnitudes for O, Ni, and Cu reside at 534, 857, and 979 eV, consecutively. The saturation magnetization constricts with the elevation of Ni²⁺ content, while the magnetic hysteresis loop resembles the superparamagnetic attitude. The optical spectra present the possibility of direct and indirect transitions in the prepared nanoceramics. Energy gap (value and type), refractive index, and real and imaginary dielectric constant were extracted. The energy gap approaches 3.75 eV and 3.71 eV for direct and indirect transitions correspondingly with (0.7) Ni²⁺. The antimicrobial and the toxicity performance of all inspected nanocomposites were conducted against pathogenic microbes. The attained results evidenced that SMZC-0.7Ni possesses energetic antimicrobial potential against all targeted microbes. The investigated SMZC-0.7Ni nanocomposite functioned to eradicate frequent waterborne pathogens in wastewater at an appropriate dose (100 mg/L), demonstrating that SMZC can be utilized as a competent disinfectant in the municipal wastewater decontamination process. Inherently, SMZC-0.7Ni can be employed as an excellent nano-weapon against multiple dangerous microorganisms.

A Multifunctional Layered Nickel Silicate Nanogenerator of Synchronous Oxygen Self-supply and Superoxide Radical Generation for Hypoxic Tumor Therapy

Oxygen consumption but hypoxic tumor environment has been considered as the major obstacle in photodynamic therapy. Although oxygen-supplied strategies have been reported extensively, they still suffer from the complicated system and unsatisfied PDT efficiency. Herein, one-component layered nickel silicate nanoplatforms (LNS NPs) are successfully synthesized using natural vermiculite as the silica source, which can simultaneously supply oxygen (O₂) and generate superoxide radicals (O₂^-•) under near-infrared irradiation. The appropriate electron band structure endows LNS NPs with attractive optical properties, where the bandgap edges determine the performance of redox activity and spectral response characteristic. Evidenced by both in vitro and in vivo investigations, LNS NPs can generate sufficient superoxide radicals under 660 nm laser irradiation to induce tumor cell apoptosis even in a severe hypoxic environment, which benefits from self-supplied oxygen. Besides, the photoacoustic oxy-hem imaging and histologic assay further demonstrated that the generated oxygen can relieve the inherent intratumoral hypoxia. Therefore, LNS NPs not only serve as superoxide radical generator but also produce oxygen to modulate hypoxia, suggesting that it can be used for superoxide radical-mediated photodynamic therapy with enhanced antitumor effect.

Facile hydrothermal synthesis and enhanced electrochemical properties of a layered NiSiO/RGO nanocomposite with an interesting dandelion-like structure

Materials with unique structures can exhibit different properties and are widely studied in the preparation of new materials. Herein we reported a hydrothermal method to fabricate a layered nickel silicate/reduced graphene oxide (NiSiO/RGO) nanocomposite with an interesting dandelion-like structure. The morphology, composition, and electrochemical performance of RGO, NiSiO, and NiSiO/RGO were comparatively investigated in the current work. The results showed that the NiSiO/RGO nanocomposite has a dandelion-like hollow core-shell structure and shows good electrochemical performance. Compared with NiSiO, the original discharge capacity of NiSiO/RGO increased from 1291.6 mA h g^-1 to 1653.9 mA h g^-1; meanwhile, the reversible specific capacity of NiSiO/RGO increased from 649.6 mA h g^-1 to 691.4 mA h g^-1 after testing at a current density of 100 mA g^-1 for 100 cycles. Moreover, the prepared NiSiO/RGO maintained a coulombic efficiency of about 97% after the initial charging and discharging cycle. This unique hollow dandelion-like structure enhanced the electrical conductivity and further resulted in lower diffusion resistance and higher reversible capacity. This work demonstrated that the layered NiSiO/RGO with an interesting dandelion-like structure can act as an alternative anode material for lithium-ion batteries.

Anode Materials for Aqueous Zinc Ion Batteries: Mechanisms, Properties, and Perspectives

Aqueous Zn-ion batteries (ZIBs) are promising safe energy storage systems that have received considerable attention in recent years. Based on the electrochemical behavior of Zn²⁺ in the charging and discharging process, herein we review the research progress on anode materials for use in aqueous ZIBs based on two aspects: Zn deposition and Zn²⁺ intercalation. To date, Zn dendrite, corrosion, and passivation issues have restricted the development of aqueous ZIBs. However, many strategies have been developed, including structural design, interface protection of the Zn anode, Zn alloying, and using polymer electrolytes. The main aim is to stabilize the Zn stripping/plating layer and limit side reactions. Zn²⁺-intercalated anodes, with a high Zn²⁺ storage capacity to replace the current metal Zn anode, are also a potential option. Finally, some suggestions have been put forward for the subsequent optimization strategy, which are expected to promote further development of aqueous ZIBs.

An aqueous miscible organic (AMO) process for layered double hydroxides (LDHs) for the enhanced properties of polypropylene/LDH composites

AMO D-LDH (h) antioxidants are fabricated using an acetone solvent, and the modified time is optimized based on the anti-aging performance of PP/D-LDH (h).

Rational design of multi-walled carbon nanotube@hollow Fe3O4@C coaxial nanotubes as long-cycle-life lithium ion battery anodes

In this work, we report a high-performance anode material created by rationally encapsulating multi-walled carbon nanotubes (MWNTs) within hollow Fe₃O₄ nanotubes followed by applying a carbon coating. When tested for lithium storage, as-prepared MWNT@hollow Fe₃O₄@C coaxial nanotubes present high specific capacity, superior rate performance, and outstanding cycling stability. It is capable of delivering high capacities of 758 mA h g^-1 at 500th cycle at 0.2 A g^-1, and 409 mA h g^-1 after 1000 cycles at a high rate of 1.5 A g^-1. This excellent performance can be attributed to its unique architecture, which provides high electrical conductivity, offers enough void space for volume accommodation, and mitigates the pulverization of Fe₃O₄ during cycles.

A New Class of Ternary Compound for Lithium-Ion Battery: from Composite to Solid Solution

Searching for high-performance cathode materials is a crucial task to develop advanced lithium-ion batteries (LIBs) with high-energy densities for electrical vehicles (EVs). As a promising lithium-rich material, Li₂MnO₃ delivers high capacity over 200 mAh g^-1 but suffers from poor structural stability and electronic conductivity. Replacing Mn⁴⁺ ions by relatively larger Sn⁴⁺ ions is regarded as a possible strategy to improve structural stability and thus cycling performance of Li₂MnO₃ material. However, large difference in ionic radii of Mn⁴⁺ and Sn⁴⁺ ions leads to phase separation of Li₂MnO₃ and Li₂SnO₃ during high-temperature synthesis. To prepare solid-solution phase of Li₂MnO₃-Li₂SnO₃, a buffer agent of Ru⁴⁺, whose ionic radius is in between that of Mn⁴⁺ and Sn⁴⁺ ions, is introduced to assist the formation of a single solid-solution phase. The results show that the Li₂RuO₃-Li₂MnO₃-Li₂SnO₃ ternary system evolves from mixed composite phases into a single solid-solution phase with increasing Ru content. Meanwhile, discharge capacity of this ternary system shows significantly increase at the transformation point which is ascribed to the improvement of Li⁺/e^- transportation kinetics and anionic redox chemistry for solid-solution phase. The role of Mn/Sn molar ratio of Li₂RuO₃-Li₂MnO₃-Li₂SnO₃ ternary system has also been studied. It is revealed that higher Sn content benefits cycling stability of the system because Sn⁴⁺ ions with larger sizes could partially block the migration of Mn⁴⁺ and Ru⁴⁺ from transition metal layer to Li layer, thus suppressing structural transformation of the system from layered-to-spinel phase. These findings may enable a new route for exploring ternary or even quaternary lithium-rich cathode materials for LIBs.