MXenes
are two-dimensional metal carbides or nitrides that are
currently proposed in many applications thanks to their unique attributes
including high conductivity and accessible surface. Recently, a synthetic
route was proposed to prepare MXenes from the molten salt etching
of precursors allowing for the preparation of MXene (denoted as MS-MXenes,
for molten salt MXene) with tuned surface termination groups, resulting
in improved electrochemical properties. However, further delamination
of as-prepared multilayer MS-MXenes still remains a major challenge.
Here, we report on the successful exfoliation of MS-Ti3C2T
x
via the
intercalation of the organic molecule TBAOH (tetrabutylammonium hydroxide),
followed by sonication to separate the layers. The treatment time
could be adapted to tune the wetting behavior of the MS-Ti3C2T
x
. As a result, a self-supported
Cl-terminated MXene film could be prepared by filtration. Finally,
MS-Ti3C2T
x
used
as a Li-ion battery anode could achieve a high specific capacity of
225 mAh g–1 at a 1C rate together with an excellent
rate capability of 95 mAh g–1 at 167C. These results
also show that tuning of the surface chemistry of MXene is of key
importance to this field with the likely result being increased electrochemical
performance.
Improving product selectivity by controlling the spatial organization of functional sites at the nanoscale is a critical challenge in bifunctional catalysis. We present a series of composite bifunctional catalysts consisting of one‐dimensional zeolites (ZSM‐22 and mordenite) and a γ‐alumina binder, with platinum particles controllably deposited either on the alumina binder or inside the zeolite crystals. The hydroisomerization of n‐heptane demonstrates that the catalysts with platinum particles on the binder, which separates platinum and acid sites at the nanoscale, leads to a higher yield of desired isomers than catalysts with platinum particles inside the zeolite crystals. Platinum particles within the zeolite crystals impose pronounced diffusion limitations on reaction intermediates, which leads to secondary cracking reactions, especially for catalysts with narrow micropores or large zeolite crystals. These findings extend the understanding of the “intimacy criterion” for the rational design of bifunctional catalysts for the conversion of low‐molecular‐weight reactants.
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