2 research outputs found
MOF-Templated Fabrication of Hollow Co<sub>4</sub>N@N-Doped Carbon Porous Nanocages with Superior Catalytic Activity
Metallic
Co<sub>4</sub>N catalysts have been considered as one of the most
promising non-noble materials for heterogeneous catalysis because
of their high electrical conductivity, great magnetic property, and
high intrinsic activity. However, the metastable properties seriously
limit their applications for heterogeneous water phase catalysis.
In this work, a novel Co-metal–organic framework (MOF)-derived
hollow porous nanocages (PNCs) composed of metallic Co<sub>4</sub>N and N-doped carbon (NC) were synthesized for the first time. This
hollow three-dimensional (3D) PNC catalyst was synthesized by taking
advantage of Co-MOF as a precursor for fabricating 3D hollow Co<sub>3</sub>O<sub>4</sub>@C PNCs, along with the NH<sub>3</sub> treatment
of Co-oxide frames to promote the in situ conversion of Co-MOF to
Co<sub>4</sub>N@NC PNCs, benefiting from the high intrinsic activity
and electron conductivity of the metallic Co<sub>4</sub>N phase and
the good permeability of the hollow porous nanostructure as well as
the efficient doping of N into the carbon layer. Besides, the covalent
bridge between the active Co<sub>4</sub>N surface and PNC shells also
provides facile pathways for electron and mass transport. The obtained
Co<sub>4</sub>N@NC PNCs exhibit excellent catalytic activity and stability
for 4-nitrophenol reduction in terms of low activation energy (<i>E</i><sub>a</sub> = 23.53 kJ mol<sup>–1</sup>), high
turnover frequency (52.01 × 10<sup>20</sup> molecule g<sup>–1</sup> min<sup>–1</sup>), and high apparent rate constant (<i>k</i><sub>app</sub> = 2.106 min<sup>–1</sup>). Furthermore,
its magnetic property and stable configuration account for the excellent
recyclability of the catalyst. It is hoped that our finding could
pave the way for the construction of other hollow transition metal-based
nitride@NC PNC catalysts for wide applications
Oxygen Vacancy-Reinforced Water-Assisted Proton Hopping for Enhanced Catalytic Hydrogenation
Water-assisted
proton hopping (WAPH) has been intensively
investigated
for promoting the performance of metal oxide-supported catalysts for
hydrogenation. However, the effects of the structure of the metal
oxide support on WAPH have received little attention. Herein, we construct
oxygen vacancy-bearing, MoO3–x-supported
Pd nanoparticle catalysts (Pd/MoO3–x-R), where the oxygen vacancies can promote WAPH,
thereby facilitating catalytic hydrogenation. The experimental results
and theoretical calculations show that the oxygen vacancies favor
the adsorption of water, which assists the proton hopping across the
surface of the metal oxide, enhancing the catalytic hydrogenation.
Our finding will provide a potential approach to the design of metal
oxide-supported catalysts for hydrogenation