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OER (oxygen evolution reaction) is a critical reaction in several storage and conversion systems for renewable and clean electrochemical energies, including solar fuel devices, metal–air batteries, as well as regenerative fuel and water splitting cells. Regarding the shortcomings of OER, apart from the sluggish kinetics and high reaction overpotential, the reaction rate and overpotential are difficult to be optimized simultaneously. Herein, a novel hierarchical particle–sheet-structured Fe-doped NixP electrocatalyst is developed, which presents abundant interfaces between crystalline particle and amorphous sheet. The OER overpotential is reduced to 204 mV at 20 mA cm−2 current density, while it is reduced to 225 and 231 mV at 100 and 300 mA cm−2, respectively. The Fe-doped NixP electrocatalyst also shows fast reaction kinetics, whose Tafel slope is a remarkable 25 mV dec−1. For an electrolytic cell whose cathode and anode are Pt/C/NF and Fe–NixP/NF, respectively, a mere 1.446 V voltage is necessary to drive a 10 mA cm−2 current density for achieving overall water-splitting property. Notably, it also works stably at considerably high current densities of 500 and 1000 mA cm−2, representing high potential for commercial applications. [ABSTRACT FROM AUTHOR]

Complexes (bmim)2[Cu3(μ3-Cl)2(μ-pz)3Cl3] (1), (bmim)[Cu3(μ3-OH)(μ-pz)3Cl3] (2) and (bmim)2[Cu3(μ3-OH)(μ-Cl)(μ-pz)3Cl3] (3) were synthesized (bmim+ = 1-butyl-3-methylimidazolium, pz− = pyrazolato anion). Dianionic complexes 1 and 3 were obtained as crystalline solids, whereas the monoanionic complex 2 was obtained as a viscous paste. Magnetic susceptibility and X-band EPR studies revealed intramolecular ferromagnetic interactions for 1 with small magnetoanisotropy in its ground state (D3/2∼ 10−3 cm−1) and intramolecular antiferromagnetic interactions for 2 and 3 (−285 and −98 cm−1 average J, respectively) with important magnetic anisotropy in their ground states stemming from a combination of low magnetic symmetry and antisymmetric exchange interactions. Thermal studies revealed a clear melting point of 140 °C for 1, which is lower than that of its PPN+ and Bu4N+ analogues (1PPN and 1Bu4N, respectively, PPN+ = bis(triphenylphosphine)iminium). Upon cooling, 1 remains molten down to 70 °C. Mixtures of the salts 1, 1PPN and 1Bu4N, exhibited modified melting behaviours, with the mixtures exhibiting lower melting points than those of either of their pure components. [ABSTRACT FROM AUTHOR]

A table of contents for the September 14, 2016 issue of the journal "CrystEngComm" is presented.

The catalytic conversion of glucose to 5-hydroxymethylfurfural (5-HMF) is highly desirable, but the 5-HMF yield obtained using heterogeneous catalysts is still low compared to homogeneous catalysts, and the mechanism is not elucidated completely. In addition, the isolation and purification of 5-HMF still present a challenge as degradation reactions take place and side products form. The formation of 5-HMF from glucose has been reported using several solid acid catalysts; still metal–organic framework (MOF) catalysts could, so far, catalyze the cascade reaction of glucose to 5-HMF only in low yields of less than 16%. Glucose conversion using MOFs is little investigated and here sulfonated MIL-101Cr (MIL-SO3H) was found to achieve 29% conversion of glucose to 5-HMF after 24 h in a THF : H2O (v : v 39 : 1) mixture. The conversion of maltose resulted in 50% 5-HMF yield (saccharide solutions were 5 wt%). When the reaction was carried out in pure THF using MIL catalysts no product was formed, revealing the indispensability of water for the glucose-to-5-HMF conversion. Importantly, MIL-SO3H preferentially leads to 5-HMF over levulinic acid (molar ratio 1 : 0.3), while the catalysts Amberlyst-15 and sulfuric acid form mostly levulinic acid in 5-HMF to levulinic acids ratios of 1 : 3 and 1 : 10, respectively. At the same time, MIL-NO2 is the most selective, yielding only 5-HMF and showing no formation of levulinic acid. Using 5-HMF as a substrate did not result in any conversion to levulinic acid in the presence of MIL-SO3H, thereby ruling out the catalytic formation of levulinic acid from 5-HMF. Catalyst recycle experiments showed that MIL-SO3H stays porous and crystalline, but becomes deactivated through fouling by humin formation. With the use of ethanol as an alternative reaction medium, the formation of insoluble humins could be prevented, but the yield of 5-HMF and 5-ethyl-HMF decreased. [ABSTRACT FROM AUTHOR]

A table of contents for the February 7, 2016 issue is presented.

Large-scale WO3 nanowire patterns have been successfully fabricated on a 3.5 inch glass substrate at atmospheric pressure by a simple no-catalyst method. The nanowires were observed to have a mean length of about 40 μm, and their aspect ratio reaches 200. The nanowires were proven to be single crystalline WO3 with a monoclinic structure. It is found that the growth region and growth density of the WO3 nanowires differ with the interval or the width of the W stripes. By combination of designing a series of experiments and analyzing the growth kinetics theory, a novel self-supported vapor–solid (SVS) mechanism is proposed to be responsible for the formation of WO3 nanowires. Field emission (FE) measurements show that the WO3 nanowire patterns have excellent FE performance, which have a low turn-on field of 2.9 V μm−1 and good field emission uniformity of over 85%. Moreover, this SVS method may provide a helpful reference on low-temperature and no-catalyst growth of other metal oxide nanostructure arrays at atmospheric pressure. [ABSTRACT FROM AUTHOR]

Mg2+, Cr3+ and Ti4+ with various valences at the ratio of 0.02 were used to dope, in order to improve the electrochemical performances of LiFePO4/C. LiFe0.98Mg0.02PO4/C (LFMPC), LiFe0.97Cr0.02PO4/C (LFCPC) and LiFe0.96Ti0.02PO4/C (LFTPC) were successfully synthesized by a carbothermal reduction method using FePO4·2H2O as the iron source and phenol-formaldehyde resin as the reducing agent and carbon source. The reaction mechanism is put forward. A LiFePO4 crystallite develops very well, and the lattice constants decrease after doping. LFTPC possesses the largest conductivity of 8.01 × 10−4 S cm−1, compared to LFMPC and LFCPC. The capacities of LFMPC, LFCPC and LFTPC at 0.1 C are 126.2 mA h g−1, 132.3 mA h g−1 and 134.7 mA h g−1 respectively, which are much larger than the 122.4 mA h g−1 of LiFePO4/C. LFTPC possesses the maximum capacity of 83.1 mA h g−1 at 3 C and a stable potential platform of 3.3 V. The energy gap of LFTPC is 0.61 eV, which is smaller than the 0.63 eV and 0.65 eV of Cr3+ and Mg2+ doped LiFePO4/C, respectively. The vacancy content of LFTPC is much more than for the other samples. This improves the electronic conductivity of doped LiFePO4/C. It is found that Ti4+ plays a significant role in improving the electronic conductivity and performances of LiFePO4/C. [ABSTRACT FROM AUTHOR]

The inorganic material cobalt selenide (CoSe), in crystalline form, possesses an optimal band gap matchable to the maximum of the solar spectrum, a high optical absorption coefficient and good conductivity. These characteristics make it quite suitable for use as a photo-electrode in solar conversion devices. However, it is difficult to obtain crystalline, uniform and stoichiometric deposits by conventional methods due to the large difference in their melting points. In view of this, we present a facile, low temperature chemical bath deposition route for the synthesis of highly ordered cobalt selenide thin films. Cobalt nitrate, sodium selenosulphate and ammonia were employed for the synthesis. The films were characterized using X-ray diffraction, optical absorbance, photoluminescence, electrical conductivity, scanning electron microscopy and EDS techniques. The analysis revealed a poly-crystalline structure in a stoichiometric, cubic form with a leaf-like morphology. The size and shape of the ‘leaf’ structure was observed to be uniform. A band gap of 1.7 eV was observed. The room temperature photoluminescence spectra displayed a strong, symmetrical peak at 1.7 eV confirming the directness of the band gap, while the conductivity measurements confirmed the semiconducting nature of the film with a single type of conduction mechanism. As per our literature survey on the chemical synthesis, this is the first attempt for the synthesis of poly-crystalline CoSe in thin film form. [ABSTRACT FROM AUTHOR]

A table of contents for the issue is presented.

A general and facile approach for tailoring the multicolor output and shapes of lanthanide-ion doped fluoride upconversion nanoparticles (UCNPs) within a given composition is presented. By adjusting the temperature and time in the thermolysis procedure, the color output and shapes of NaYF4:20%Yb, 2%Er UCNPs can be readily manipulated. The nanoparticles were characterized through the use of transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and upconversion luminescence spectroscopy. It is shown that the relative intensities of green emissions gradually increased with the rise of temperature and prolongation of growth time under excitation of 980 nm, which resulted in multicolor output of NaYF4:20%Yb, 2%Er UCNPs. Simultaneously, the shapes for UCNPs can also be controlled. TEM images, estimated micro-stress by Williamson–Hall methodology and a series of control experiments and analyses reveal that crystallinity is mainly responsible for the multicolor output of UCNPs. Based on the above method, the tailoring of color output is also successfully realized in Ho3+and Tm3+ions. It is expected that this method may be used to tune the physical properties of other nanoparticles, and these multicolored UCNPs are promising for applications in multiplexed bioimaging, biodetection, display, other optical technologies, etc. [ABSTRACT FROM AUTHOR]