4 research outputs found
Synthesis of 2D Germanane (GeH):a New, Fast, and Facile Approach
Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a beta-CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (E-g) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells
NMR and EPR Structural Analysis and Stability Study of Inverse Vulcanized Sulfur Copolymers
Sulfur
copolymers with high sulfur content find a broad range of
applications from Li–S batteries to catalytic processes, self-healing
materials, and the synthesis of nanoparticles. Synthesis of sulfur-containing
polymers via the inverse vulcanization technique gained a lot of attention
due to the feasibility of the reaction to produce copolymers with
high sulfur content (up to 90 wt %). However, the interplay between
the cross-linker and the structure of the copolymers has not yet been
fully explored. In the present work, the effect of the amount of 1,3-diisopropenyl
benzene (DIB) cross-linker on the structural stability of the copolymer
was thoroughly investigated. Combining X-ray diffraction and differential
scanning calorimetry, we demonstrated the partial depolymerization
of sulfur in the copolymer containing low amount of cross-linker (<30
wt % DIB). On the other hand, by applying NMR and electron paramagnetic
resonance techniques, we have shown that increasing the cross-linker
content above 50 wt % leads to the formation of radicals, which may
severely degrade the structural stability of the copolymer. Thus,
an optimum amount of cross-linker is essential to obtain a stable
copolymer. Moreover, we were able to detect the release of H<sub>2</sub>S gas during the cross-linking reaction as predicted based on the
abstraction of hydrogen by the sulfur radicals and therefore we emphasize
the need to take appropriate precautions while implementing the inverse
vulcanization reaction
Crystal and Electronic Facet Analysis of Ultrafine Ni2P Particles by Solid-State NMR Nanocrystallography
Structural and morphological control of crystalline nanoparticles is crucial in the field of heterogeneous catalysis and the development of “reaction specific” catalysts. To achieve this, colloidal chemistry methods are combined with ab initio calculations in order to define the reaction parameters, which drive chemical reactions to the desired crystal nucleation and growth path. Key in this procedure is the experimental verification of the predicted crystal facet and its corresponding electronic structure, which in case of nanostructured materials becomes extremely difficult. Here, by employing 31P solid-state nuclear magnetic resonance (ssNMR) aided by advanced density functional theory (DFT) calculations to obtain and assign the Knight shifts, we succeeded in determining the crystal and electronic structure of the terminating surfaces of ultrafine Ni2P nanoparticles at atomic scale resolution. Our work highlights the potential of ssNMR nanocrystallography as a unique tool in the emerging field of facet-engineered nanocatalysts