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Defect‐engineering is a viable strategy to improve the activity of nanocatalysts for the oxygen evolution reaction (OER), whose slow kinetics still strongly limits the broad market penetration of electrochemical water splitting as a sustainable technology for large‐scale hydrogen production. High‐entropy spinel oxides (HESOs) are in focus due to their great potential as low‐cost OER electrocatalysts. In this work, electrospun HESO nanofibers (NFs), based on (Cr,Mn,Fe,Co,Ni), (Cr,Mn,Fe,Co,Zn) and (Cr,Mn,Fe,Ni,Zn) combinations, with granular architecture and oxygen‐deficient surface are produced by calcination at low temperature (600 or 500 °C), characterized by a combination of benchtop analytical techniques and evaluated as electrocatalysts for OER in alkaline medium. The variation of HESO composition and calcination temperature produces complex and interdependent changes in the morphology of the fibers, crystallinity and inversion degree of the spinel oxide, concentration of the oxygen‐vacancies, cation distribution in the lattice, which mirror on different electrochemical properties of the fibers. The best electrocatalytic performance (overpotential and Tafel slope at 10 mA cm−2: 360 mV and 41 mV dec−1, respectively) pertains to (Cr1/5Mn1/5Fe1/5Co1/5Ni1/5)3O4 NFs calcined at 500 °C and results from the lower outer 3d‐electron number, eg filling closer to its optimal value and higher occupation of 16d sites by the most redox‐active species. [ABSTRACT FROM AUTHOR]

MXenes are an emerging class of materials considered for many applications, such as sensors, catalysis, energy storage devices. The main obstacle towards their massive implementation is the synthesis requiring the direct use of HF as etching agent. The development of alternative synthetic routes exploiting in‐situ forming HF agents is the main strategies to overcome this limitation. In this study four different etching methods based on the use of NH4HF2, NaF−HCl, HBF4, and NaBF4−HCl are compared to produce Ti3C2Tx from Ti3AlC2 towards the application of MXenes in sodium ion batteries. Three of such etching methods have already been reported while one is here presented for the first time. The structural analysis of the obtained products is based on X‐ray diffraction (XRD), scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDX), and X‐ray photoelectron spectroscopy (XPS) analysis. All the materials have been tested in half‐cell configuration vs. Na; the charge/discharge profiles and the C‐rate tests are discussed and related to specific structural features. Overall, the results reveal that the MXene obtained using the HBF4 etching agent under mild conditions is comparable both in structure and functional properties to the benchmark material, i. e., the MXene produced using HF at 5 % concentration. Indeed, the MXene synthetized with the HBF4 presents the lowest mean voltage and potential hysteresis and shows the highest first cycle efficiency (69.7 %), overcoming the performance of the MXene produced with 5 % HF (67 %). This study proves the possibility to produce MXene with a more sustainable route. [ABSTRACT FROM AUTHOR]

As highlighted by the recent roadmaps from the European Union and the United States, water electrolysis is the most valuable high‐intensity technology for producing green hydrogen. Currently, two commercial low‐temperature water electrolyzer technologies exist: alkaline water electrolyzer (A‐WE) and proton‐exchange membrane water electrolyzer (PEM‐WE). However, both have major drawbacks. A‐WE shows low productivity and efficiency, while PEM‐WE uses a significant amount of critical raw materials. Lately, the use of anion‐exchange membrane water electrolyzers (AEM‐WE) has been proposed to overcome the limitations of the current commercial systems. AEM‐WE could become the cornerstone to achieve an intense, safe, and resilient green hydrogen production to fulfill the hydrogen targets to achieve the 2050 decarbonization goals. Here, the status of AEM‐WE development is discussed, with a focus on the most critical aspects for research and highlighting the potential routes for overcoming the remaining issues. The Review closes with the future perspective on the AEM‐WE research indicating the targets to be achieved. [ABSTRACT FROM AUTHOR]

New inorganic‐organic hybrid anion exchange membranes are produced after incorporation of tantalum oxide into trimethylammonium‐functionalized polyethylene pyrrole‐co‐polyethylene ketone (functionalized polyketone, FPK), obtained by the chemical modification of a polyketone polymer. The influence of tantalum oxide fillers on the properties of the synthesized membranes is investigated. The interaction between inorganic fillers and the polymer chains is studied using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR‐FTIR). The thermal analysis of the FPK membranes reveals they are thermally stable at up to 250°C. However, the incorporation of the inorganic fillers reduces the thermal stability. Modulated Differential Scanning Calorimetry (MDSC) results indicate that the inclusion of inorganic fillers leads to an increase in crystallinity. This study reports that the properties of the bulk polymer can be tuned by controlling the degree of functionalization and content of inorganic fillers, as confirmed by Near Ambient Pressure X‐Ray Photoelectron Spectroscopy (NAP‐XPS) studies. Finally, Broadband Electrical Spectroscopy (BES) studies demonstrate that the hybrid membranes are characterized by several polarization phenomena contributing to the overall ion conductivity of the material, which at RT is of 1.46 and 1.61 mS cm−1 for the FPK cast membrane and the hybrid membrane with 5.0 wt.% of Ta2O5 filler, respectively. [ABSTRACT FROM AUTHOR]

In this report, the conductivity mechanism of Ca2+‐ion in polyoxyethylene (POE) solid polymer electrolytes (SPEs) for calcium secondary batteries is investigated by broadband electrical spectroscopy studies. SPEs are obtained by dissolving into the POE hosting matrix three different calcium salts: CaTf2, Ca(TFSI)2 and CaI2. The investigation of the electric response of the synthetized SPEs reveals the presence in materials of two polarization phenomena and two dielectric relaxation events. It is demonstrated that the nature of the anion (i. e. steric hindrance, charge density and ability to act as coordination ligand) and the density of "dynamic crosslinks" of SPEs is fundamental in the establishment of ion‐ion/ion‐polymer interactions. The long‐range charge migration processes occurring along the two revealed percolation pathways of the electrolytes are generally coupled with the polymer host dynamics and depend on the temperature and the anion nature. This study offers the needed tools for understanding Ca2+ conduction in POE‐based electrolytes. [ABSTRACT FROM AUTHOR]

Abstract: The numerous potential benefits of incorporating anion‐exchange membranes (AEMs), in place of proton‐exchange membranes (PEMs), in energy storage and conversion technologies renders their development of fundamental importance for the continued evolution of alternative energy systems. However, the widespread implementation of AEMs is currently plagued by a range of problems including lower conductivity (with respect to PEMs), poor stability, and high cost. This study reports the conversion of polyketone, one of the world's most mass produced and cheap polymers, to a new highly tuneable polymer architecture, functionalized polyketone (FPK), that demonstrates a range of excellent properties rendering it a significant prospect for AEM materials. The thermal, processing, and ion‐conducting properties of FPK are governed by the amount and nature of the newly formed N‐substituted pyrrole pendant side groups. At 80 °C, the quarternized pyridyl FPK derivative (4MPyrFPK) yields ion‐conductivities of 8.6 and 10.5 mS cm−1 in the iodide and hydroxide forms. In addition, the hydroxide form of 4MPyr‐FPK demonstrates remarkable stability toward the typically problematic alkaline conditions. No chemical decomposition is observed to the membrane after imbibing it in KOH solution for 72 h, and furthermore, the ion‐conductivity is demonstrated to remain constant for at least 30 d at 80 °C. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of new “Pt‐free” electrocatalysts (ECs) for the oxygen reduction reaction (ORR) is reported. The ECs are characterized by a hierarchical “core‐shell” morphology; the “core” is made of graphene, that is covered by a cratered, microporous carbon nitride (CN) “shell”. The latter supports nanoparticles of M1 and Sn metals (M1=Co; Ni) in “coordination nests”. The latter are holes in the CN matrix, whose walls consist of N‐ and C‐ligands. Two groups of ECs are studied: (i) “pristine” ECs; and (ii) “activated” ECs, that are obtained from the “pristine” ECs by means of a suitable activation process (A) aimed at improving the performance in the ORR. Here, the interplay existent between (i) the chemical composition, morphology, structure and A; and (ii) the ORR performance and mechanism is investigated. The resulting insights improve the fundamental understanding of this family of ECs and open the door to the devising of new preparations of “Pt‐free” ECs for the ORR, which: (i) are stabilized by a CN matrix and; (ii) exhibit an improved performance. [ABSTRACT FROM AUTHOR]

Non-medical-grade industrial nets are often implemented in developing countries as affordable alternative to surgical meshes for hernia repair. Even if there is clear evidence about their repairing reliability, their physicochemical and mechanical properties have been not fully investigated. This works compares three industrial nets with different textile patterns, and a surgical mesh of the same polymer. Nets are autoclave-sterilized and characterized through scanning electron microscope, Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and uniaxial tensile tests. Spectral and thermal analyses reveal that all samples are based on poly(ethylene terephthalate). Differences are found in phase conformations with modifications in amorphous, ordered amorphous, and crystalline domains. Changes in material characteristics do not affect mechanical properties, which are mainly ascribable to the textile pattern. Industrial nets show a stiffening behavior different from the almost linear anisotropic response of surgical mesh. However, non-medical-grade nets could be potentially applied for surgeries once their biocompatibility and in vivo stability have been evaluated. Non-medical-grade industrial nets are used as low-cost alternative to surgical meshes for hernia repair in less developed countries. Nets sterilization modifies their phase conformation, due to the interaction with water, but do not affect mechanical properties. Even tough industrial nets show a different stiffening behavior, physicochemical characterization confirms a similarity to standard surgical meshes. [ABSTRACT FROM AUTHOR]

Molecular engineering of manganese(II) diamine diketonate precursors is a key issue for their use in the vapor deposition of manganese oxide materials. Herein, two closely related β-diketonate diamine MnII adducts with different fluorine contents in the diketonate ligands are examined. The target compounds were synthesized by a simple procedure and, for the first time, thoroughly characterized by a joint experimental-theoretical approach, to understand the influence of the ligand on their structures, electronic properties, thermal behavior, and reactivity. The target compounds are monomeric and exhibit a pseudo-octahedral coordination of the MnII centers, with differences in their structure and fragmentation processes related to the ligand nature. Both complexes can be readily vaporized without premature side decompositions, a favorable feature for their use as precursors for chemical vapor deposition (CVD) or atomic layer deposition applications. Preliminary CVD experiments at moderate growth temperatures enabled the fabrication of high-purity, single-phase Mn3O4 nanosystems with tailored morphology, which hold great promise for various technological applications. [ABSTRACT FROM AUTHOR]

Front Cover: Critical Analysis of MXene Production with In-Situ HF Forming Agents for Sustainable Manufacturing (ChemElectroChem 23/2022) Anode material, electrode, HF free etching, Mxene, sodium ion batteries Keywords: anode material; electrode; HF free etching; Mxene; sodium ion batteries EN anode material electrode HF free etching Mxene sodium ion batteries 1 1 1 12/15/22 20221213 NES 221213 B The Front Cover b shows schematically the synthesis of the MXene 2D material (on the right) using acidic solutions starting from the lamellar 3D MAX phase (on the left) avoiding the direct use of HF to improve the sustainability of the MXenes production. [Extracted from the article]

The quest for new electrolyte and cathode materials is a crucial point for beyond-lithium-ion energy storage systems. Following this, an electrolyte for secondary magnesium batteries based on a new iodoaluminate ionic liquid and δ-MgI2 is reported. Promising electrochemical performance in terms of Mg plating-stripping, coulombic efficiency, and conductivity, demonstrates the potential of this iodine-based system for future Mg secondary batteries. [ABSTRACT FROM AUTHOR]

A critical roadblock toward practical Mg-based energy storage technologies is the lack of reversible electrolytes that are safe and electrochemically stable. Here, we report on high-performance electrolytes based on 1-ethyl-3-methylimidazolium chloride (EMImCl) doped with AlCl3 and highly amorphous δ-MgCl2. The phase diagram of the electrolytes reveals the presence of four thermal transitions that strongly depend on salt content. High-level density functional theory (DFT)-based electronic structure calculations substantiate the structural and vibrational assignment of the coordination complexes. A 3D chloride-concatenated dynamic network model accounts for the outstanding redox behaviour and the electric and magnetic properties, providing insight into the conduction mechanism of the electrolytes. Mg anode cells assembled using the electrolytes were cyclically discharged at a high rate (35 mA g−1), exhibiting an initial capacity of 80 mA h g−1 and a steady-state voltage of 2.3 V. [ABSTRACT FROM AUTHOR]

New high voltage and high capacity storage systems are needed to sustain the increasing energy demand set by the portable electronics and auto­motive fields. Due to their good electrochemical performance, lithium-transition metal-phosphates (LiMPO4) seem to be very attractive as cathode materials for lithium secondary batteries. Here the synthesis and the characterization of five high voltage cathodes for lithium batteries, based on lithium-iron, lithium-nickel, lithium-cobalt phosphates are described. The effect of differing degrees of cobalt and nickel doping on structure, morphology, and the electrochemical properties of the different materials is thoroughly studied. Transition metal atoms in these materials are found to be vicariant within the olivine crystal structure; however, the lattice parameters and cell volume can be modulated by varying the nickel/cobalt ratio during the synthesis. High performance battery prototypes in terms of voltage (>4.0 V), specific capacity (125 mAh g−1), specific energy (560 mWh g−1), and cyclic life (>150 cycles) are also demonstrated. [ABSTRACT FROM AUTHOR]

Owing to the numerous benefits obtained when operating proton exchange membrane fuel cells at elevated temperature (>100 °C), the development of thermally stable proton exchange membranes that demonstrate conductivity under anhydrous conditions remains a significant goal for fuel cell technology. This paper presents composite membranes consisting of poly[2,2′-( m-phenylene)-5,5′-bibenzimidazole] (PBI4N) impregnated with a ZrO2 nanofiller of varying content (ranging from 0 to 22 wt %). The structure-property relationships of the acid-doped and undoped composite membranes have been studied using thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, wide-angle X-ray scattering, infrared spectroscopy, and broadband electrical spectroscopy. Results indicate that the level of nanofiller has a significant effect on the membrane properties. From 0 to 8 wt %, the acid uptake as well as the thermal and mechanical properties of the membrane increase. As the nanofiller level is increased from 8 to 22 wt % the opposite effect is observed. At 185 °C, the ionic conductivity of [PBI4N(ZrO2)0.231](H3PO4)13 is found to be 1.04×10−1 S cm−1. This renders membranes of this type promising candidates for use in high-temperature proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

ABSTRACT The effect of steam on the micro-phase structure and mechanical properties of different block copolymers used in biomedical devices is investigated via FT-IR, tensile tests and dynamic mechanical analysis (DMA). Steam sterilization, commonly performed on medical devices and simulated in this work, affects the copolymers' morphology, due to high temperature and humidity conditions. FT-IR analysis reveals that steam induces a modification in the crystalline conformations of copolymers with a pre-existing hydrogen bonding network, that is, thermoplastic polyurethanes (TPU) and poly(ether-block-amide) (PEBA), while it does not significantly affect the domain conformation in styrenic block copolymers (SEBS), due to weak interaction with water. As a consequence, relevant changes of the mechanical properties, closely related to the microdomain structure, are found for TPU and PEBA after sterilization, while SEBS mechanical behavior remains stable, as demonstrated by tensile tests and DMA results. For this reason, SEBS is suggested as the best choice in terms of durability in biomedical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1337-1346 [ABSTRACT FROM AUTHOR]

Forsterite (Mg2SiO4) ceramics are excellent candidate materials for components operating with high-frequency electromagnetic waves, due to their low dielectric losses. In this paper, we discuss a novel processing approach for the production of forsterite monoliths based on the mixing of silicone resins with MgO nano-sized particles. The interaction between the nano-sized filler and the silica provided by the oxidative decomposition of silicones was so effective that forsterite formed at only 800 °C, i.e., just above the transformation temperature of the preceramic polymers. The approach based on silicones modified with oxide fillers was followed also when trying to suppress undesirable phases, such as unreacted MgO and enstatite (MgSiO3); in particular TiO2, added in form of nano- and micro-sized powders, was useful both as active filler, promoting the formation of forsterite solid solution and Mg-titanates, and as passive filler, leading to a forsterite/rutile composite. Both Ti-doped forsterite and the composite featured interesting dielectric characteristics (low dielectric constant, high quality factor), despite the presence of some residual porosity (≈15%, after firing at 1100 °C). [ABSTRACT FROM AUTHOR]

In this work, an easy, quick and reproducible wet-synthesis coprecipitation route starting from oxalate precursors was optimised to synthesise cobalt, nickel, zinc and magnesium spinel ferrites CoFe2O4, NiFe2O4, ZnFe2O4 and MgFe2O4, as well as the manganese perovskite ferrite MnFeO3. Crystalline purity and crystallite sizes ranging from 30 to 190 nm were investigated by means of powder X-ray diffraction, and uniform morphology of the particles was shown through transmission electron microscopy. The chosen synthetic route afforded an excellent stoichiometric control over the products, as confirmed by combined X-ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectroscopy analyses. The site geometry, degree of inversion in the spinels and chemical environments in the ferrites were explored by Mössbauer spectroscopy. The thermal evolution of the compounds during calcination and the decomposition pattern of the oxalates were studied through differential scanning calorimetry coupled with thermogravimetric analysis as well as in situ temperature-programmed X-ray diffraction. Magnetic properties of these oxides, as well as the transition of the perovskite from paramagnetic to ferrimagnetic behaviour at low temperatures, were investigated by superconducting quantum interferometer magnetometry. [ABSTRACT FROM AUTHOR]

GHz broadband electrical spectroscopy (G-BES) is adopted to investigate the molecular relaxations and interactions occurring within the system in an oxygen- and water-free atmosphere in the 300 kHz-20 GHz and −40 to 250 °C frequency and temperature ranges, respectively. A new electrolyte for magnesium secondary batteries that can transfer magnesium ions efficiently is presented. This electrolyte is based on polyethylene glycol 400 and a polymeric form of δ-MgCl2. The information obtained by G-BES is crucial for studying the conduction mechanism of these new electrolytes. [ABSTRACT FROM AUTHOR]

Renewable poly(ether-block-amide)s (PEBAs), with different polyamide/polyether (PA/PE) ratios, are characterized for the development of biomedical devices. The effect of the chemical composition on the mechanical properties is studied via Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile tests, dynamic mechanical analysis (DMA), and broadband electric spectro­scopy (BES). FTIR spectroscopy evidences the presence of different PA crystalline domains depending on the PA/PE ratio, as also evidenced by TGA and DSC. Such differences influence the molecular dynamics, as shown by DMA and BES, and the mechanical properties characterized by tensile tests. Indeed, PEBAs with a higher PA/PE ratio are stiffer due to a higher crystalline degree. [ABSTRACT FROM AUTHOR]

Hyper-cross-linked resins stemming from a gel-type poly-chloromethylated poly(styrene- co-divinylbenzene) resin (GT) have been investigated by a multi-methodological approach based on elemental analysis, scanning electron microscopy, X-ray microanalysis, and solvent absorption. The hyper-cross-linking of the parent resin was accomplished by Friedel-Crafts alkylation of the phenyl rings of the resins with the chloromethyl groups. This produced a permanent pore system comprising both micropores (<2.0 nm in diameter) and mesopores (2.2 nm). The chloromethyl groups that did not react in the hyper-cross-linking step were transformed into methylmercaptan groups and the latter were then converted into sulfonic groups by oxidation with hydrogen peroxide. By this procedure the extensive permanent porosity of the parent unsulfonated hyper-cross-linked polymer (HGT) was retained by the sulfonated polymer (HGTS). The final exchange capacity of HGTS was determined to be 0.36 mmol g−1. HGTS was easily metalated with PdII and the subsequent reduction of the metal centers with either aqueous sodium borohydride, formaldehyde, or dihydrogen produced three Pd0/HGTS nanocomposites. The metal nanoparticles had diameters in the 1-6 nm range for all the nanocomposites, as determined by TEM, but with somewhat different distributions. When formaldehyde was used, more than 90 % of the nanoparticles were less than 3 nm and their radial distribution throughout the polymer beads was quite homogeneous. These findings show that with this reducing agent the metal nanoparticles are generated within the pore system of the polymer matrix, hence their size is controlled by the dimensions of the pores of the polymeric support. [ABSTRACT FROM AUTHOR]

An extensive morphological and structural study of two bimetallic 'core-shell' carbon nitride nano-electrocatalysts with active sites based on Pt and Ni or on Pt and Fe is reported. The core-shell electrocatalysts are obtained by the pyrolysis of a precursor obtained by decorating a support composed of conducting particles with a hybrid inorganic-organic material. The electrocatalysts were investigated by high-resolution TEM, powder X-ray diffraction, and μ-Raman spectroscopy. The morphological and structural information presented here provides 1) insight into the microscopic features, affecting the electrochemical performance of the electrocatalyst materials determined in both ex situ measurements and single-cell configurations; and 2) an opportunity to study the effect of the different precursor chemistries on the structure and morphology of the bimetallic core-shell carbon nitride nano-electrocatalysts. [ABSTRACT FROM AUTHOR]

Two types of new nanocomposite proton-exchange membranes, consisting of functionalized and pristine nanoparticles of silica and silicone rubber (SR) embedded in a polytetrafluoroethylene (PTFE) matrix, were prepared. The membrane precursor was obtained from a mechanical rolling process, and the SiO2 nanoparticles were functionalized by soaking the membranes in a solution of 2-(4-chlorosulfonylphenyl)ethyl trichlorosilane (CSPhEtCS). The membranes exhibit a highly compact morphology and a lack of fibrous PTFE. At 125 °C, the membrane containing the functionalized nanoparticles has an elastic modulus (2.2 MPa) that is higher than that of pristine Nafion (1.28 MPa) and a conductivity of 3.6×10−3 S cm−1 despite a low proton-exchange capacity (0.11 meq g−1). The good thermal and mechanical stability and conductivity at T>100 °C make these membranes a promising low-cost material for application in proton-exchange membrane fuel cells operating at temperatures higher than 100 °C. [ABSTRACT FROM AUTHOR]

On page 4860, V. Di Noto and co‐workers show the first iodoaluminate ionic liquid for the development of future Mg/I2 secondary batteries. Reversible magnesium deposition/stripping with low overvoltage and high (99.94%) coulombic efficiency is achieved and a detailed investigation of the Mg interaction scenario is reported. [ABSTRACT FROM AUTHOR]

The Inside Back Cover picture shows the use of polymeric δ ‐ MgCl2 and an imidazolium ‐ based chloroaluminate ionic liquid to synthesize an innovative electrolyte for application in secondary Mg batteries. The resulting nanostructure of the ionic liquid with the chlorine ‐ concatENated Mg complex, results in unique electrochemical performance, opENing new prospectives in the field of secondary batteries. The interplay betweEN structure and electrical properties provides the opportunity to obtain a fundamENtal understanding of the conductivity mechanism and to devise and develop future electrolytes for use in electric vehicle applications. More details can be found in the Full Paper by V. Di Noto et al. on page 3069 in Issue 18, 2015. (DOI: 10.1002/cssc.201500339). [ABSTRACT FROM AUTHOR]