Design of Two-Dimensional,
Ultrathin MoS<sub>2</sub> Nanoplates Fabricated Within One-Dimensional
Carbon Nanofibers With Thermosensitive Morphology: High-Performance
Electrocatalysts For The Hydrogen Evolution Reaction
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Abstract
Two-dimensional
MoS<sub>2</sub> nanoplates within carbon nanofibers (CNFs) with monolayer
thickness, nanometer-scale dimensions and abundant edges are fabricated.
This strategy provides a well-defined pathway for the precise design
of MoS<sub>2</sub> nanomaterials, offering control over the evolution
of MoS<sub>2</sub> morphology from nanoparticles to nanoplates as
well as from mono- to several-layer structures, over a lateral dimension
range of 5 to 70 nm. CNFs play an important role in confining the
growth of MoS<sub>2</sub> nanoplates, leading to increases in the
amount of exposed edge sites while hindering the stacking and aggregation
of MoS<sub>2</sub> layers, and accelerating electron transfer. The
controlled growth of MoS<sub>2</sub> nanoplates embedded in CNFs is
leveraged to demonstrate structure-dependent catalytic activity in
the hydrogen evolution reaction (HER). The results suggest that increases
in the number of layers and the lateral dimension result in a decrease
in HER activity as a general rule. Single-layer MoS<sub>2</sub> nanoplates
with abundant edges and a lateral dimension of 7.3 nm demonstrated
the lowest hydrogen evolution reaction overpotential of 93 mV (<i>J</i> = 10 mA/cm<sup>2</sup>), the highest current density of
80.3 mA/cm<sup>2</sup> at η = 300 mV and the smallest Tafel
slope of 42 mV/decade. The ability of MoS<sub>2</sub>–CNFs
hybrids to act as nonprecious metal catalysts indicates their promise
for use in energy-related electrocatalytic applications