title: Core-shell Prussian blue analogue molecular magnet Mn(1.5)[Cr(CN)6]·mH2O@Ni(1.5)[Cr(CN)6]·nH2O for hydrogen storage.
abstract: Core-shell Prussian blue analogue molecular magnet Mn1.5[Cr(CN)6]·mH2O@Ni1.5[Cr(CN)6]·nH2O has been synthesized using a core of Mn1.5[Cr(CN)6]·7.5H2O, surrounded by a shell of Ni1.5[Cr(CN)6]·7.5H2O compound. A transmission electron microscopy (TEM) study confirms the core-shell nature of the nanoparticles with an average size of ∼25 nm. The core-shell nanoparticles are investigated by using x-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and elemental mapping, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. The Rietveld refinement of the XRD pattern reveals that the core-shell compound has a face-centered cubic crystal structure with space group Fm3m. The observation of characteristic absorption bands in the range of 2000-2300 cm(-1) in IR spectra corresponds to the CN stretching frequency of Mn(II)/Ni(II)-N≡C-Cr(III) sequence, confirming the formation of Prussian blue analogues. Hydrogen absorption isotherm measurements have been used to investigate the kinetics of molecular hydrogen adsorption into core-shell compounds of the Prussian blue analogue at low temperature conditions. Interestingly, the core-shell compound shows an enhancement in the hydrogen capacity (2.0 wt % at 123 K) as compared to bare-core and bare-shell compounds. The hydrogen adsorption capacity has been correlated with the specific surface area and TGA analysis of the core-shell compound. To the best of our knowledge, this is the first report on the hydrogen storage properties of core-shell Prussian blue analogue molecular magnet that could be useful for hydrogen storage applications.
authors.affiliation: Solid State Physics Division and ‡Chemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India.
authors.forename: Pramod
authors.initials: P
authors.lastname: Bhatt
authors.forename: Seemita
authors.initials: S
authors.lastname: Banerjee
authors.forename: Sharmistha
authors.initials: S
authors.lastname: Anwar
authors.forename: Mayuresh D
authors.initials: MD
authors.lastname: Mukadam
authors.forename: Sher Singh
authors.initials: SS
authors.lastname: Meena
authors.forename: Seikh M
authors.initials: SM
authors.lastname: Yusuf
keywords: Prussian blue analogues; Rietveld refinement; core−shell nanostructure; hydrogen storage; molecular magnets; transmission electron microscopy