Energy Storage: Giant Enhancement in the Supercapacitance of NiFe–Graphene Nanocomposites Induced by a Magnetic Field (Adv. Mater. 28/2019)

Breathing-Dependent Redox Activity in a Tetrathiafulvalene-Based Metal–Organic Framework

"Breathing" metal-organic frameworks (MOFs) that involve changes in their structural and physical properties upon an external stimulus are an interesting class of crystalline materials due to their range of potential applications including chemical sensors. The addition of redox activity opens up a new pathway for multifunctional "breathing" frameworks. Herein, we report the continuous breathing behavior of a tetrathiafulvalene (TTF)-based MOF, namely MUV-2, showing a reversible swelling (up to ca. 40% of the volume cell) upon solvent adsorption. Importantly, the planarity of the TTF linkers is influenced by the breathing behavior of the MOF, directly impacting on its electrochemical proper…

Prussian blue@MoS2 layer composites as highly efficient cathodes for sodium- and potassium-ion batteries

Prussian blue (PB) represents a simple, economical, and eco‐friendly system as cathode material for sodium‐ion batteries (SIBs). However, structural problems usually worsen its experimental performance thus motivating the search for alternative synthetic strategies and the formation of composites that compensate these deficiencies. Herein, a straightforward approach for the preparation of PB/MoS2‐based nanocomposites is presented. MoS2 provides a 2D active support for the homogeneous nucleation of porous PB nanocrystals, which feature superior surface areas than those obtained by other methodologies, giving rise to a compact PB shell covering the full flake. The nanocomposite exhibits an ex…

CVD synthesis of carbon spheres using NiFe-LDHs as catalytic precursors: structural, electrochemical and magnetoresistive properties

The gram-scale synthesis of carbon spheres with a diameter of ca. 740 nm has been achieved by means of a chemical vapour deposition method using NiFe-layered double hydroxides as a solid catalytic precursor. The presence of the catalyst (FeNi3) allows controlling the final size distribution, resulting in a monodisperse sample. Their structural properties exhibited a high degree of graphitization according to their ID/IG ratio. In addition, their morphological features were unveiled by FIB-SEM and HRTEM, showing that they are formed by solid inner cores, and presenting labile chain-like structures due to accretion procedures. The solution and posterior sonication of the samples in toluene ga…

Cover Feature: Fundamental Insights into the Covalent Silane Functionalization of NiFe Layered Double Hydroxides (Chem. Eur. J. 29/2020)

Insights into the formation of metal carbon nanocomposites for energy storage using hybrid NiFe layered double hydroxides as precursors

[EN] NiFe-carbon magnetic nanocomposites prepared using hybrid sebacate intercalated layered double hydroxides (LDHs) as precursors are shown to be of interest as supercapacitors. Here, the low-temperature formation mechanism of these materials has been deciphered by means of a combined study using complementaryin situ(temperature-dependent) techniques. Specifically, studies involving X-ray powder diffraction, thermogravimetry coupled to mass spectrometry (TG-MS), statistical Raman spectroscopy (SRS), aberration-corrected scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) have been carried out. The experimental results confirm the early formation o…

Metal-functionalized covalent organic frameworks as precursors of supercapacitive porous N-doped graphene

Covalent Organic Frameworks (COFs) based on polyimine with several metal ions (FeIII, CoII and NiII) adsorbed into their cavities have shown the ability to generate N-doped porous graphene from their pyrolysis under controlled conditions. These highly corrugated and porous graphene sheets exhibit high values of specific capacitance, which make them useful as electrode materials for supercapacitors.

Giant Enhancement in the Supercapacitance of NiFe–Graphene Nanocomposites Induced by a Magnetic Field

The rapid rise in energy demand in the past years has prompted a search for low-cost alternatives for energy storage, supercapacitors being one of the most important devices. It is shown that a dramatic enhancement (≈1100%, from 155 to 1850 F g-1 ) of the specific capacitance of a hybrid stimuli-responsive FeNi3 -graphene electrode material can be achieved when the charge/discharge cycling is performed in the presence of an applied magnetic field of 4000 G. This result is related to an unprecedented magnetic-field-induced metal segregation of the FeNi3 nanoparticles during the cycling, which results in the appearance of small Ni clusters (<5 nm) and, consequently, in an increase in pseudoca…

Fundamental Insights into the Covalent Silane Functionalization of NiFe Layered Double Hydroxides

Layered double hydroxides (LDHs) are a class of 2D anionic materials exhibiting wide chemical versatility and promising applications in different fields, ranging from catalysis to energy storage and conversion. However, the covalent chemistry of this kind of 2D materials is still barely explored. Herein, the covalent functionalization with silanes of a magnetic NiFe-LDH is reported. The synthetic route consists of a topochemical approach followed by anion exchange reaction with surfactant molecules prior to covalent functionalization with the (3-aminopropyl)triethoxysilane (APTES) molecules. The functionalized NiFe-APTES was fully characterized by X-ray diffraction, infrared spectroscopy, e…

Alkoxide-intercalated CoFe-layered double hydroxides as precursors of colloidal nanosheet suspensions: structural, magnetic and electrochemical properties

Alkoxide-intercalated CoFe-layered double hydroxides (CoFe–LDHs) were synthesized via the non-aqueous methanolic route. According to powder X-ray diffraction and field emission scanning electron microscopy, they exhibit a nanosized plate-like morphology with a basal space of 9.21 A. The hydrolysis of the material in water leads to colloidal suspensions of nanosheets with lateral dimensions of about 20 nm and thicknesses of ca. 4 nm as demonstrated by atomic force microscopy and dynamic light scattering. Atomic resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy confirm the high crystalline quality of the crystals and the proper Co/Fe stoichio…

Small-pore driven high capacitance in a hierarchical carbon via carbonization of Ni-MOF-74 at low temperatures

A hierarchical porous carbon prepared via direct carbonization of Ni-MOF-74 loaded with furfuryl alcohol at 450 °C displays high specific capacitance in comparison with other MOF-derived carbons as a result of the formation of micropores smaller than 1 nm.

Solvent-free synthesis of ZIFs: a route toward the elusive Fe(II) analogue of ZIF-8

Herein we report the synthesis of an elusive metal-organic framework, the iron(II) analogue of ZIF-8 with the formula Fe(2-methylimidazolate) , here denoted as MUV-3. The preparation of this highly interesting porous material, inaccessible by common synthetic procedures, occurs in a solvent-free reaction upon addition of an easily detachable template molecule, yielding single crystals of MUV-3. This methodology can be extended to other metals and imidazolate derivatives, allowing the preparation of ZIF-8, ZIF-67, and the unprecedented iron(II) ZIFs Fe(2-ethylimidazolate) and Fe(2-methylbenzimidazolate) . The different performance of MUV-3 toward NO sorption, in comparison to ZIF-8, results …

Alkoxide-intercalated NiFe-layered double hydroxides magnetic nanosheets as efficient water oxidation electrocatalysts

Alkoxide-intercalated NiFe-layered double hydroxides were synthesized via the nonaqueous methanolic route. These nanoplatelets exhibit high crystalline quality as demonstrated by atomic resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy. Moreover, the presence of the alkoxide moieties has been unambiguously demonstrated by means of thermogravimetric analysis coupled to a mass spectrometer. These NiFe-LDHs can be exfoliated in water or organic solvents and processed into homogeneous ultra-thin films (&lt; 3nm thick) with the assistance of O2-plasma. The study of their behaviour as water oxidation electrocatalysts has shown an outstanding perf…

CCDC 1830490: Experimental Crystal Structure Determination

Related Article: Manuel Souto, Jorge Romero, Joaquín Calbo, Inigo J. Vitorica-Yrezabal, Jose L Zafra, Juan Casado Cordón, Enrique Ortí, Aron Walsh, Guillermo Minguez Espallargas|2018|J.Am.Chem.Soc.|140|10562|doi:10.1021/jacs.8b05890

CCDC 1899779: Experimental Crystal Structure Determination

Related Article: Javier López-Cabrelles, Jorge Romero, Gonzalo Abellán, Mónica Giménez-Marqués, Miguel Palomino, Susana Valencia, Fernando Rey, Guillermo Minguez Espallargas|2019|J.Am.Chem.Soc.|141|7173|doi:10.1021/jacs.9b02686

CCDC 1830488: Experimental Crystal Structure Determination

Related Article: Manuel Souto, Jorge Romero, Joaquín Calbo, Inigo J. Vitorica-Yrezabal, Jose L Zafra, Juan Casado Cordón, Enrique Ortí, Aron Walsh, Guillermo Minguez Espallargas|2018|J.Am.Chem.Soc.|140|10562|doi:10.1021/jacs.8b05890

CCDC 1830489: Experimental Crystal Structure Determination

Related Article: Manuel Souto, Jorge Romero, Joaquín Calbo, Inigo J. Vitorica-Yrezabal, Jose L Zafra, Juan Casado Cordón, Enrique Ortí, Aron Walsh, Guillermo Minguez Espallargas|2018|J.Am.Chem.Soc.|140|10562|doi:10.1021/jacs.8b05890

CCDC 1825894: Experimental Crystal Structure Determination

Related Article: Javier López-Cabrelles, Jorge Romero, Gonzalo Abellán, Mónica Giménez-Marqués, Miguel Palomino, Susana Valencia, Fernando Rey, Guillermo Minguez Espallargas|2019|J.Am.Chem.Soc.|141|7173|doi:10.1021/jacs.9b02686

CCDC 1853491: Experimental Crystal Structure Determination

Related Article: Manuel Souto, Jorge Romero, Joaquín Calbo, Inigo J. Vitorica-Yrezabal, Jose L Zafra, Juan Casado Cordón, Enrique Ortí, Aron Walsh, Guillermo Minguez Espallargas|2018|J.Am.Chem.Soc.|140|10562|doi:10.1021/jacs.8b05890

CCDC 1899778: Experimental Crystal Structure Determination

Related Article: Javier López-Cabrelles, Jorge Romero, Gonzalo Abellán, Mónica Giménez-Marqués, Miguel Palomino, Susana Valencia, Fernando Rey, Guillermo Minguez Espallargas|2019|J.Am.Chem.Soc.|141|7173|doi:10.1021/jacs.9b02686

Cover Picture. Energy Storage: Giant Enhancement in the Supercapacitance of NiFe-Graphene Nanocomposites Induced by a Magnetic Field (Adv. Mater. 28/2019)

The application of external magnetic fields to NiFe–graphene nanocomposites during the galvanostatic charge/discharge cycles induces a dramatic metal phase segregation, forming nanometric metal clusters of Ni with an outstanding electrochemical activity. This metal segregation leads to an enhancement in the capacitance of the nanocomposite, as described by Gonzalo Abellán, Eugenio Coronado, and co-workers in article number 1900189. PNICTOCHEM 804110 (G.A.) CIDEGENT/2018/001