A simple microwave-assisted fluorolytic sol-gel synthesis of 30 nm sized FeF3 nanocrystals supported on partially reduced graphene oxide is reported. The as-fabricated nanostructures used as positive electrodes in Li-ion batteries show capacity retention as high as 150 mA h g(-1) even after having sustained repeated charge-discharge cycles.

We describe the preparation of the first crystalline compounds based on arylboronate ligands PhB(OH)(3)(-) coordinated to metal cations: [Ca(PhB(OH)(3))(2)], [Sr(PhB(OH)(3))(2)]·H(2)O, and [Ba(PhB(OH)(3))(2)]. The calcium and strontium structures were solved using powder and single-crystal X-ray diffraction, respectively. In both cases, the structures are composed of chains of cations connected through phenylboronate ligands, which interact one with each other to form a 2D lamellar structure. The temperature and pH conditions necessary for the formation of phase-pure compounds were investigated: changes in temperature were found to mainly affect the morphology of the crystallites, whereas strong variations in pH were found to affect the formation of pure phases. All three compounds were characterized using a wide range of analytical techniques (TGA, IR, Raman, XRD, and high resolution (1)H, (11)B, and (13)C solid-state NMR), and the different coordination modes of phenylboronate ligands were analyzed. Two different kinds of hydroxyl groups were identified in the structures: those involved in hydrogen bonds, and those that are effectively "free" and not involved in hydrogen bonds of any significant strength. To position precisely the OH protons within the structures, an NMR-crystallography approach was used: the comparison of experimental and calculated NMR parameters (determined using the Gauge Including Projector Augmented Wave method, GIPAW) allowed the most accurate positions to be identified. In the case of the calcium compound, it was found that it is the (43)Ca NMR data that are critical to help identify the best model of the structure.

The electrochemical reaction of bronze-type FeF 3 •0.33H 2 O, synthesized via a simple room-temperature solution route, with lithium was investigated by operando Mossbauer spectroscopy and X-ray diffraction. The two techniques revealed a complex electrochemical mechanism where the pristine crystalline compound is gradually transformed into an amorphous material containing nanodomains of a FeF 2 -like rutile structure mixed to iron nanoparticles. Upon charge, two steps are dominating the electrochemical behavior: partial reformation of the initial bronze structure and oxidation to Fe(III). This reaction mechanism, however, is not constant, and noticeable variation can be observed during galvanostatic cycling (up to 55 cycles) until eventually an amorphous material containing rutile nanodomains composes the final active electrode. The material performance, under the form of a fluoride/graphene oxide composite, is also assessed with respect to the long-term effect of the depth of first discharge.