2 research outputs found
Nickel–Silicide Colloid Prepared under Mild Conditions as a Versatile Ni Precursor for More Efficient CO<sub>2</sub> Reforming of CH<sub>4</sub> Catalysts
Preparing highly active and stable non-noble-metal-based
dry reforming
catalysts remains a challenge today. In this context, supported nickel
nanoparticles with sizes of 1.3 ± 0.2 and 2.1 ± 0.2 nm were
synthesized on silica and ceria, respectively, via a two-step colloidal
approach. First, 2-nm nickel–silicide colloids were synthesized
from Ni(COD)<sub>2</sub> and octylsilane at low temperature; they
were subsequently dispersed onto supports prior to reduction under
H<sub>2</sub>. The resulting catalysts display high activity in dry
reforming compared to their analogues prepared using conventional
approaches, ceria providing greatly improved catalyst stability
Solid-Phase Polarization Matrixes for Dynamic Nuclear Polarization from Homogeneously Distributed Radicals in Mesostructured Hybrid Silica Materials
Mesoporous hybrid silica–organic
materials containing homogeneously
distributed stable mono- or dinitroxide radicals covalently bound
to the silica surface were developed as polarization matrixes for
solid-state dynamic nuclear polarization (DNP) NMR experiments. For
TEMPO-containing materials impregnated with water or 1,1,2,2-tetrachloroethane,
enhancement factors of up to 36 were obtained at ∼100 K and
9.4 T without the need for a glass-forming additive. We show that
the homogeneous radical distribution and the subtle balance between
the concentration of radical in the material and the fraction of radicals
at a sufficient inter-radical distance to promote the cross-effect
are the main determinants for the DNP enhancements we obtain. The
material, as well as an analogue containing the poorly soluble biradical
bTUrea, is used as a polarizing matrix for DNP NMR experiments of
solutions containing alanine and pyruvic acid. The analyte is separated
from the polarization matrix by simple filtration