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Complex 3D macrostructured nanoparticles are transformed from amorphous silica into pure polycrystalline α-quartz using catalytic quantities of alkaline earth metals as devitrifying agent. Walls as thin as 10 nm could be crystallized without losing the architecture of the particles. The roles of cation size and the mol% of the incorporated devitrifying agent in crystallization behavior are studied, with Mg2+, Ca2+, Sr2+ and Ba2+ all producing pure α-quartz under certain conditions. [ABSTRACT FROM AUTHOR]

A one pot synthesis of alumina supported faceted nickel nanoparticles is carried out following a simple, inexpensive, and sustainable pathway. Tailoring the different chemical steps of catalyst preparation allow the faceted morphology to be maintained while reducing the organic leftover. Moreover, this work shows the key role of the halide ions on the nanoparticles shaping that occurs during the reduction step under H2. The predominant role of the {111} facets on the performance of the resulting supported nanocatalysts is also demonstrated. Indeed, catalytic tests in selective hydrogenation of polyunsaturated hydrocarbons performed for both faceted nanocatalysts and reference Ni show a clear selectivity enhancement for the former. The positive impact of {111} faceted Ni catalysts on hydrogenation selectivity is of particular interest to reduce the purification steps after the catalyzed reaction. [ABSTRACT FROM AUTHOR]