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Downsizing well-established materials to the nanoscale is a key route to novel functionalities, in particular if different functionalities are merged in hybrid nanomaterials. Hybrid carbon-based hierarchical nanostructures are particularly promising for electrochemical energy storage since they combine benefits of nanosize effects, enhanced electrical conductivity and integrity of bulk materials. We show that endohedral multiwalled carbon nanotubes (CNT) encapsulating high-capacity (here: conversion and alloying) electrode materials have a high potential for use in anode materials for lithium-ion batteries (LIB). There are two essential characteristics of filled CNT relevant for application in electrochemical energy storage: (1) rigid hollow cavities of the CNT provide upper limits for nanoparticles in their inner cavities which are both separated from the fillings of other CNT and protected against degradation. In particular, the CNT shells resist strong volume changes of encapsulates in response to electrochemical cycling, which in conventional conversion and alloying materials hinders application in energy storage devices. (2) Carbon mantles ensure electrical contact to the active material as they are unaffected by potential cracks of the encapsulate and form a stable conductive network in the electrode compound. Our studies confirm that encapsulates are electrochemically active and can achieve full theoretical reversible capacity. The results imply that encapsulating nanostructures inside CNT can provide a route to new high-performance nanocomposite anode materials for LIB., Comment: Invited

In the present work, we demonstrate different synthesis procedures for filling carbon nanotubes (CNTs) with equimolar binary nanoparticles of the type Fe–Co. The CNTs act as templates for the encapsulation of magnetic nanoparticles and provide a protective shield against oxidation as well as prevent nanoparticle agglomeration. By variation of the reaction parameters, we were able to tailor the sample purity, degree of filling, the composition and size of the filling particles, and therefore, the magnetic properties. The samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), superconducting quantum interference device (SQUID) and thermogravimetric analysis (TGA). The Fe–Co-filled CNTs show significant enhancement in the coercive field as compared to the corresponding bulk material, which make them excellent candidates for several applications such as magnetic storage devices.

A new type of Heusler nanoparticles of the formula Fe3Ga has been prepared by facile synthesis approaches using pre-fabricated multi-walled carbon nanotubes. The tubes act as a template and a coating to protect the magnetic material from oxidation and agglomeration. For the purpose of comparison, the Fe3Ga bulk material was also prepared by a novel method from the metal precursors. The morphology, structural determinations and the magnetic properties of both types of materials are presented. Compared to the bulk material, an enhancement in coercivity was observed for the nanoparticles which make them excellent candidates for magnetic storage devices. Since bulk Galfenol is a known magnetostrictive material, it is worth studying the effect of downsizing this material to the nanoscale dimension on such properties.

The olive oil industry in Palestine is an important and widely spread one and accomplished with the release of large amounts of olive-mills wastewater. This wastewater represents a significant environmental problem due to its high phenolic content. In this work, the photocatalytic degradation of the some phenolic compounds (gallic acid, oleuropein and resorcinol) present in olive-mills wastewater using the synthesized nanoparticles of mixed SnO2-MgO catalyst and solar irradiation was performed. The nanoparticles of mixed SnO2-MgO catalyst with different ratios were prepared by sol gel method using a modified procedure. The obtained particles were characterized by SEM and XRD. The particle size was determined as 4.32 ± 0.42 nm which is much smaller than those previously prepared by standard procedures. The degradation percentage of phenolic compounds was measured by UV spectrophotometry. The effect of time, catalyst amount and phenolic compound concentration on degradation efficiency was studied. The maximum degradation was achieved using SnO2-MgO (4:1) catalyst, 2.5 mg catalyst per 5 mL solution, within the time of 60-120 min and ranged from 51 to 90 % for different concentrations of phenolic compounds.

Nanosized particles of cobalt ferrite CoFe2O4 incorporated into multi-walled carbon nanotubes (CNT) have been studied as anode material for Li-ion batteries. In order to evaluate the benefits of CNT shells, the results are compared to bare CoFe2O4 nanoparticles. Electrochemical measurements by means of cyclic voltammetry and galvanostatic cycling show typical redox activity associated with the ferrite conversion reaction which implies that the filled nanomaterial is electrochemically active. Galvanostatic cycling measurements reveal better cycling stability of the CNT-incorporated compared to the bare ferrite nanoparticles. The data imply that embedding nanoparticles inside the protective and conductive shells of CNTs opens a way to utilize high theoretical capacities of CoFe2O4 for electrochemical energy storage.

In the present work, different synthesis procedures have been demonstrated to fill carbon nanotubes (CNTs) with Fe1-xNix alloy nanoparticles (x = 0.33, 0.5). CNTs act as templates for the encapsulation of magnetic nanoparticles, and provide a protective shield against oxidation as well as prevent nanoparticles agglomeration. By variation of the reaction parameters, the purity of the samples, degree of filling, the composition and size of filling nanoparticles have been tailored and therefore the magnetic properties. The samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Bright-field (BF) TEM tomography, X-ray powder diffraction, superconducting quantum interference device (SQUID) and thermogravimetric analysis (TGA). The Fe1-xNix-filled CNTs show a huge enhancement in the coercive fields compared to the corresponding bulk materials, which make them excellent candidates for several applications such as magnetic storage devices.