Single crystals of the new compound Cu(SeO)F were successfully synthesized via a hydrothermal method, and the crystal structure was determined from single-crystal X-ray diffraction data. The compound crystallizes in the orthorhombic space group Pnma with the unit cell parameters a = 7.066(4) Å, b = 9.590(4) Å, and c = 5.563(3) Å. Cu(SeO)F is isostructural with the previously described compounds CoTeOF and CoSeOF. The crystal structure comprises a framework of corner- and edge-sharing distorted [CuOF] octahedra, within which [SeO] trigonal pyramids are present in voids and are connected to [CuOF] octahedra by corner sharing. The presence of a single local environment in both the F andSe solid-state MAS NMR spectra supports the hypothesis that O and F do not mix at the same crystallographic positions. Also the specific phonon modes observed with Raman scattering support the coordination around the cations. At high temperatures the magnetic susceptibility follows the Curie-Weiss law with Curie temperature of Θ = -173(2) K and an effective magnetic moment of μ ∼ 2.2 μ. Antiferromagnetic ordering below ∼44 K is indicated by a peak in the magnetic susceptibility. A second though smaller peak at ∼16 K is tentatively ascribed to a magnetic reorientation transition. Both transitions are also confirmed by heat capacity measurements. Raman scattering experiments propose a structural phase instability in the temperature range 6-50 K based on phonon anomalies. Further changes in the Raman shift of modes at ∼46 K and ∼16 K arise from transitions of the magnetic lattice in accordance with the susceptibility and heat capacity measurements.
Deep Eutectic Solvents (DES) are a new class of ionic conductive compounds attracting significant attention as greener alternatives to costly ionic liquids. Herein, we developed novel mixed ionic-electronic conducting materials...
Investigation of new high‐efficiency catalysts for the oxygen evolution reaction (OER) is important for propelling the practical applications of water splitting. Here we report the Aurivillius compound CoBi2O2F4 to be a novel catalyst for catalytic OER. After liquid exfoliation of CoBi2O2F4 crystals in isopropanol, the resulting thin sheets deliver a low overpotential of 334 mV and a small Tafel slope of 47 mV dec−1 for catalytic OER, exhibiting substantially higher activity and faster kinetics compared with as‐synthesized crystals. This attributes to the increase in accessible surface area and dangling bonds on the edges providing more active sites exposed on the surface after exfoliation. The positive effects of F− anions to benefit OH− adsorption/combination and p‐block Bi3+ cations to direct reactants to preferred sites are proposed to synergistically improve the Co‐active centers for catalysis; based on this, the OER reaction mechanism on this new catalyst is discussed.
The new quaternary iodate KCu(IO3)3 has been prepared by hydrothermal synthesis. KCu(IO3)3 crystallizes in the monoclinic space group P21/n with unit cell parameters a = 9.8143(4) Å, b = 8.2265(4) Å, c = 10.8584(5) Å, β = 91.077(2)°, and z = 4. The crystals are light blue and translucent. There are three main building units making up the crystal structure: [KO10] irregular polyhedra, [CuO6] distorted octahedra, and [IO3] trigonal pyramids. The Jahn–Teller elongated [CuO6] octahedra connect to each other via corner sharing to form [CuO5]∞ zigzag chains along [010]; the other building blocks separate these chains. The Raman modes can be divided into four groups; the lower two groups into mainly lattice modes involving K and Cu displacements and the upper two groups into mainly bending and stretching modes of [IO3E], where E represents a lone pair of electron. At low temperatures, the magnetic susceptibility is characterized by a broad maximum centered at ∼5.4 K, characteristic for antiferromagnetic short-range ordering. Long-range magnetic ordering at TC = 1.32 K is clearly evidenced by a sharp anomaly in the heat capacity. The magnetic susceptibility can be very well described by a spin S = 1/2 antiferromagnetic Heisenberg chain with a nearest-neighbor spin exchange of ∼8.9 K.
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