Synthesis and characterization of layered metal sulfates containing M(µ3-OH/F)2(M = Mg, Co) diamond chains.

Cobalt and magnesium sulfates of the compositions, [C4N2H12]2[Co3F2(SO4)3(H2O)2], (1) and [NH4]2[Mg3(OH)2(SO4)3(H2O)2], (2), respectively, have been synthesized under hydro/solvothermal conditions, and are characterized by IR spectra, elemental analysis, powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), and X-ray single-crystal diffraction. 1 and 2 crystallized in the orthorhombic space groups Pnma and Cmc2 respectively. While 1 is templated by the organic piperazinium cation, 2 is obtained in the presence of ammonium ions. The layered structures are formed by the diamond chains comprising of M3(µ3-OH/F)2 units (M = Co: 1, Mg: 2). Magnetic studies of 1 reveal its ferromagnetic nature with a transition at 10.8 K and show it does not exhibit spin-glass freezing. Isothermal magnetization shows a hysteresis loop at 2.5 K with a coercive field of 1200 Oe and remnant magnetization of 0.1µB. A sharp λ-like anomaly is also seen in the heat capacity curve, favoring long range magnetic ordering below Tc.

3D cuboidal vanadium diselenide embedded reduced graphene oxide hybrid structures with enhanced supercapacitor properties.

The electrochemical supercapacitor performance of a VSe2-reduced graphene oxide (RGO) hybrid has been reported for the first time. The hybrid was synthesized via a one-step hydrothermal route at different concentrations of graphene oxide, i.e. 0.15, 0.3, and 0.75 wt%. Enhanced supercapacitor performances were observed in the case of the hybrid obtained at 0.3 wt% of GO. It showed a specific capacitance of ∼680 F g-1 at a mass normalised current of 1 A g-1 which was ∼6 and ∼5 fold higher than those of bare VSe2 and bare RGO, respectively. Furthermore, a high energy density of ∼212 W h kg-1, power density of ∼3.3 kW kg-1, and ∼81% retention of the initial capacitance even after 10 000 cycles of charge-discharge were observed.

Kagome-type isostructural 3D-transition metal fluorosulfates with spin 3/2 and 1: synthesis, structure and characterization.

Two isostructural transition metal fluorosulfates based on Co and Ni metal ions with the molecular composition of [H3O][M(SO4)F] (where M = Co(II) for 1 and Ni(II) for 2) were synthesized under solvothermal conditions and structurally characterized by single crystal X-ray analysis. The materials were further characterized by complementary techniques like TGA, FTIR and PXRD. The 3D-crystal lattice consists of a kagome-type entity where sulfate groups replaced one of the metal nodes when compared with true kagome structures. Magnetic studies of the complexes were also performed which showed that the interactions at the metal center are antiferromagnetic in nature. The proton conductivity increases with the increase in humidity and was found to be 7.9 × 10-6 S cm-1 for 2 at RH = 98%.