Two-dimensional (2D) semiconductors, especially transition metal dichalcogenides (TMDs), have been envisioned as promising candidates in extending Moore’s law. To achieve this, the controllable growth of wafer-scale TMDs single crystals or periodic single-crystal patterns are fundamental issues. Herein, we present a universal route for synthesizing arrays of unidirectionally orientated monolayer TMDs ribbons (e.g., MoS2, WS2, MoSe2, WSe2, MoSxSe2-x), by using the step edges of high-miller-index Au facets as templates. Density functional theory calculations regarding the growth kinetics of specific edges have been performed to reveal the morphological transition from triangular domains to patterned ribbons. More intriguingly, we find that, the uniformly aligned TMDs ribbons can merge into single-crystal films through a one-dimensional edge epitaxial growth mode. This work hereby puts forward an alternative pathway for the direct synthesis of inch-scale uniform monolayer TMDs single-crystals or patterned ribbons, which should promote their applications as channel materials in high-performance electronics or other fields.
Improving the adhesion property of
graphene directly grown on an
insulating substrate is essential for promoting the reliability and
durability of the related applications. However, effective approaches
have rarely been reported, especially for vertically oriented graphene
(VG) films grown on insulating templates. To tackle this, we have
developed a facile synthetic strategy by introducing an ultrathin
(10 nm-thick) titanium (Ti) film on a quartz glass substrate as the
adhesion layer, for plasma-enhanced chemical vapor deposition (PECVD)
growth of VG films. This synthetic process induces the formation of
Ti, oxygen (O), carbon (C)-containing adhesion layer (Ti (O, C)),
offering improved interfacial adhesion due to the formation of chemical
bonds among Ti and C atoms. Dramatically improved surface and interface
stabilities have been achieved, with regard to its counterpart without
a Ti adhesion layer. Moreover, we have also realized precise controls
of the transparent/conductive property, surface roughness, and hydrophobicity, etc., by varying the VG film growth time. We have also demonstrated
the very intriguing application potentials of the hybrids in light-dimming
related fields, that is, electro-heating defogging lenses and neutral
density filters toward medical endoscope defogging and camera photography.
Two-dimensional (2D) PtSe2 has attracted intensive
attention
in energy-related fields, due to its high catalytic activity, electrical
conductivity, and chemical stability, etc. However, the active sites
of 2D PtSe2 nanosheets synthesized on conventional planar
substrates are limited to the edge sites. Herein, the direct synthesis
of three-dimensional (3D) vertically oriented 1T-PtSe2 nanosheets
featured with abundant edge sites is reported on the nanoporous gold
template via a chemical vapor deposition route. Moreover, Ar+ sputtering treatment of as-grown sample is introduced to generate
more abundant surface defects, thus boosting the electrocatalytic
activity of the inert basal planes. In this regard, the vertical growth
configuration and abundant defects of PtSe2 nanosheets
are revealed to afford remarkable electrocatalytic activity for hydrogen
evolution reaction. This work hereby provides a new route for the
morphology engineering of noble metal related transition-metal dichalcogenides
toward 3D vertical configurations, which should promote their practical
applications in high-current-density water splitting.
Self-intercalation
of native metal atoms in two-dimensional (2D)
transition metal dichalcogenides has received rapidly increasing interest,
due to the generation of intriguing structures and exotic physical
properties, however, only reported in limited materials systems. An
emerging type-II Dirac semimetal, NiTe2, has inspired great
attention at the 2D thickness region, but has been rarely achieved
so far. Herein, we report the direct synthesis of mono- to few-layer
Ni-tellurides including 1T-NiTe2 and Ni-rich stoichiometric
phases on graphene/SiC(0001) substrates under ultra-high-vacuum conditions.
Differing from previous chemical vapor deposition growth accompanied
with transmission electron microscopy imaging, this work combines
precisely tailored synthesis with on-site atomic-scale scanning tunneling
microscopy observations, offering us visual information about the
phase modulations of Ni-tellurides from 1T-phase NiTe2 to
self-intercalated Ni3Te4 and Ni5Te6. The synthesis of Ni self-intercalated Ni
x
Te
y
compounds is explained to be
mediated by the high metal chemical potential under Ni-rich conditions,
according to density functional theory calculations. More intriguingly,
the emergence of superconductivity in bilayer NiTe2 intercalated
with 50% Ni is also predicted, arising from the enhanced electron–phonon
coupling strength after the self-intercalation. This work provides
insight into the direct synthesis and stoichiometric phase modulation
of 2D layered materials, enriching the family of self-intercalated
materials and propelling their property explorations.
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