GaTe is an important III-VI semiconductor with direct bandgap; thus, it holds great potential in the field of optoelectronics. Although it is known that GaTe can exist both in monoclinic and hexagonal phases, current studies are still exclusively restricted to the monoclinic phase of two dimensional (2D) GaTe owing to the difficulty in the fabrication of 2D hexagonal GaTe. Both monoclinic and hexagonal GaTe are demonstrated in this work, which can be selectively synthesized via a physical vapor deposition method, under precisely controlled growth temperatures. The pristine Raman and non-linear optical properties of hexagonal GaTe has been systematically explored for the first time; moreover, a novel selected-area phase transition from hexagonal to monoclinic of GeTe has been achieved via fs-laser irradiation. This work may pave the way for widely use of 2D GaTe in various fields in future.a strategy for selected-area phase transition from h-GaTe to m-GaTe, which may pave the way for wide applications of GaTe in future.
Abstract2D all‐inorganic halide perovskites (2D AIHP) have attracted huge attention for their excellent optoelectronic properties and superior atmospheric stability for organic–inorganic halide perovskites. 2D AIHP has been fabricated by varied strategies, whereas a satisfied way to simultaneously reach good quality, dimensions, and uniformity is still far from achieved yet. Here, a direct thermal deposition method to synthesize 2D AIHP of lateral length up to ≈30 µm and uniform thickness down to ≈10 nm, which shows excellent optoelectronic performance comparable to the reported top‐level 2D AIHP, is proposed. A vertical mass transport instead of conventional horizontal mode is adopted, significantly enhancing the deposition stability. Furthermore, the morphologies of AIHP are switchable between nanowires and nanoflakes under the control of deposition temperature. This method may pave the way for uniform fabrication of 2D AIHP or AIHP‐based 2D heterostructures for various applications.
Adsorption isotherms of pure C2H4 and C3H6 were measured
on 11 adsorbents and at pressures
up to 0.8 MPa using a volumetric method. The Brunauer–Emmett–Teller
(BET) surface area of the adsorbents had a significant effect on adsorption
capacities of both C2H4 and C3H6. The metal organic framework MIL-101 had the highest BET
surface area and the highest adsorption capacity. For zeolite molecular
sieves 5A, the C2H4 adsorption capacity was
higher than that of C3H6, which is opposite
to the results for most adsorbents. The isosteric heats of C3H6 on AC-1, 5A, MIL-101, ZIF-8, and SG-1 were higher than
those of C2H4. The C3H6/C2H4 separation selectivities were calculated
using the ideal solution theory, and the activated carbon AC-1 had
the highest separation selectivity of 8.8.
A series
of sulfur-doped microporous carbon materials were prepared
by directly using potassium hydroxide as the activating agent. The
specific surface area and pore volume of the sample CKS-5 (activated
at 800 °C for 180 min according to an alkali/carbon ratio of
4:1) reached 2088 m2/g and 1.240 cm3/g, respectively.
The adsorption isotherms of N2, CH4, and CO2 on five samples were determined by a volumetric method to
obtain insight into the relationship between adsorption performance
and porosity. CSK-5 with a developed pore structure exhibited a higher
adsorption amount of CO2 and CH4 at high pressure.
For the selectivity, the CS sample presented the highest selectivity
for CO2/CH4, of which the selectivity of separation
reached as high as 5.86. The highest selectivity of separation of
CH4/N2 (3.644) was present on CSK-7.
Mesoporous carbon materials were synthesized via the triconstituent Co-assembly of resol, tetraethylorthosilicate (TEOS), and pluronic F127, followed by the process of polymerization. The synthesized mesoporous carbons exhibit uniform large pore sizes (3.6−6.2 nm), high surface area (940−1310 m 2 /g), and large pore volume (1.16−1.71 m 3 /g). Adsorption isotherms of CO 2 on sample MC2 were measured at 275 K with various amounts of water preadsorbed. The highest CO 2 sorption capacity reaches about 51.8 mmol/g when the weight ratio of water to dry carbon (R w ) is 2.55, which is 1.23 times as high as the highest CO 2 sorption previously obtained on CMK-3 in the presence of water. A storage capacity of 269 (V/V) was obtained at 275 K under 3.5 MPa with a packing density of 0.30 cm 3 /g. By adding tetrahydrofuran (THF) in water as a hydrate promoter, the hydrate formation pressure was decreased from 1.75 to 0.25 MPa with a THF concentration of 6.7 (mol %).
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