EASY-GOING deconvolution: Automated MQMAS NMR spectrum analysis based on a model with analytical crystallite excitation efficiencies.

The EASY-GOING deconvolution (EGdeconv) program is extended to enable fast and automated fitting of multiple quantum magic angle spinning (MQMAS) spectra guided by evolutionary algorithms. We implemented an analytical crystallite excitation model for spectrum simulation. Currently these efficiencies are limited to two-pulse and z-filtered 3QMAS spectra of spin 3/2 and 5/2 nuclei, whereas for higher spin-quantum numbers ideal excitation is assumed. The analytical expressions are explained in full to avoid ambiguity and facilitate others to use them. The EGdeconv program can fit interaction parameter distributions. It currently includes a Gaussian distribution for the chemical shift and an (extended) Czjzek distribution for the quadrupolar interaction. We provide three case studies to illustrate EGdeconv's capabilities for fitting MQMAS spectra. The EGdeconv program is available as is on our website http://egdeconv.science.ru.nl for 64-bit Linux operating systems.

The role of Ni in increasing the reversibility of the hydrogen release from nanoconfined LiBH4.

Nanoconfinement and the use of catalysts are promising strategies to enhance the reversibility of hydrogen storage in light metal hydrides. We combined nanoconfinement of LiBH4 in nanoporous carbon with the addition of Ni. Samples were prepared by deposition of 5-6 nm Ni nanoparticles inside the porous carbon, followed by melt infiltration with LiBH4. The Ni addition has only a slight influence on the LiBH4 hydrogen desorption, but significantly enhances the subsequent uptake of hydrogen under mild conditions. Reversible, but limited, intercalation of Li is observed during hydrogen cycling. X-ray diffraction shows that the initial crystalline 5-6 nm Ni nanoparticles are not present anymore after melt infiltration with LiBH4. However, transmission electron microscopy showed Ni-containing nanoparticles in the samples. Extended X-ray absorption fine structure spectroscopy proved the presence of Ni(x)B phases with the Ni-B coordination numbers changing reversibly with dehydrogenation and rehydrogenation of the sample. Ni(x)B can act as a hydrogenation catalyst, but solid-state 11B NMR proved that the addition of Ni also enhanced the reversibility of the system by influencing the microstructure of the nanoconfined LiBH4 upon cycling.