scholarly journals The Influence of Oxygen Concentration during MAX Phases (Ti3AlC2) Preparation on the α-Al2O3 Microparticles Content and Specific Surface Area of Multilayered MXenes (Ti3C2Tx)

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 353 ◽  
Author(s):  
Błażej Scheibe ◽  
Vojtech Kupka ◽  
Barbara Peplińska ◽  
Marcin Jarek ◽  
Krzysztof Tadyszak
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Oxygen Concentration ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Max Phase ◽  
Max Phases ◽  
Critical Feature ◽  
Al2o3 Particles ◽  
Α Al2o3

The high specific surface area of multilayered two-dimensional carbides called MXenes, is a critical feature for their use in energy storage systems, especially supercapacitors. Therefore, the possibility of controlling this parameter is highly desired. This work presents the results of the influence of oxygen concentration during Ti3AlC2 ternary carbide—MAX phase preparation on α-Al2O3 particles content, and thus the porosity and specific surface area of the Ti3C2Tx MXenes. In this research, three different Ti3AlC2 samples were prepared, based on TiC-Ti2AlC powder mixtures, which were conditioned and cold pressed in argon, air and oxygen filled glove-boxes. As-prepared pellets were sintered, ground, sieved and etched using hydrofluoric acid. The MAX phase and MXene samples were analyzed using scanning electron microscopy and X-ray diffraction. The influence of the oxygen concentration on the MXene structures was confirmed by Brunauer-Emmett-Teller surface area determination. It was found that oxygen concentration plays an important role in the formation of α-Al2O3 inclusions between MAX phase layers. The mortar grinding of the MAX phase powder and subsequent MXene fabrication process released the α-Al2O3 impurities, which led to the formation of the porous MXene structures. However, some non-porous α-Al2O3 particles remained inside the MXene structures. Those particles were found ingrown and irremovable, and thus decreased the MXene specific surface area.

Preparation of Nanoscale High-Purity α-Alumina Powders

2007 ◽  
Vol 336-338 ◽  
pp. 2051-2053 ◽  
Author(s):  
Xiu Lan Wu ◽  
Qiang Ren ◽  
Xuan Meng He
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Purity ◽  
High Specific Surface Area ◽  
Aluminium Isopropoxide ◽  
Reaction Progress ◽  
Α Al2o3

High-purity nanoscale α-alumina powders with high specific surface area were prepared from boehmite powders synthesized by the method of aluminium isopropoxide hydrolysis. The physiochemical transformation of boehmite powders under heat-treatment was investigated. The results showed that the reaction progress of boehmite under heat-treatment is as follows: AlO(OH) → Al2O3 (amorphous) → γ-Al2O3 → δ-Al2O3 → α-Al2O3. The phase transformation from δ-Al2O3 to α-Al2O3 begins at 1050oC, and the α-Al2O3 grains growth accelerates as temperature increases. High-purity α-Al2O3 nanometer powders with higher specific surface area can be obtained after incineration at 1100oC for 4 h.

scholarly journals Nanoporous Quasi-High-Entropy Alloy Microspheres

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 345 ◽  
Author(s):  
Lianzan Yang ◽  
Yongyan Li ◽  
Zhifeng Wang ◽  
Weimin Zhao ◽  
Chunling Qin
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
High Entropy Alloy ◽  
Face Centered Cubic ◽  
High Entropy ◽  
Hierarchical Porous

High-entropy alloys (HEAs) present excellent mechanical properties. However, the exploitation of chemical properties of HEAs is far less than that of mechanical properties, which is mainly limited by the low specific surface area of HEAs synthesized by traditional methods. Thus, it is vital to develop new routes to fabricate HEAs with novel three-dimensional structures and a high specific surface area. Herein, we develop a facile approach to fabricate nanoporous noble metal quasi-HEA microspheres by melt-spinning and dealloying. The as-obtained nanoporous Cu30Au23Pt22Pd25 quasi-HEA microspheres present a hierarchical porous structure with a high specific surface area of 69.5 m2/g and a multiphase approximatively componential solid solution characteristic with a broad single-group face-centered cubic XRD pattern, which is different from the traditional single-phase or two-phase solid solution HEAs. To differentiate, these are named quasi-HEAs. The synthetic strategy proposed in this paper opens the door for the synthesis of porous quasi-HEAs related materials, and is expected to promote further applications of quasi-HEAs in various chemical fields.

KCl-assisted activation: Moringa oleifera branch-derived porous carbon for high performance supercapacitor

2021 ◽  
Vol 45 (12) ◽  
pp. 5712-5719
Author(s):  
Yongxiang Zhang ◽  
Peifeng Yu ◽  
Mingtao Zheng ◽  
Yong Xiao ◽  
Hang Hu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Porous Carbon ◽  
High Performance ◽  
Moringa Oleifera ◽  
High Specific Surface Area ◽  
Porous Carbons

Porous carbons with a high specific surface area (2314–3470 m2 g−1) are prepared via a novel KCl-assisted activation strategy for high-performance supercapacitor.

Carbon material with high specific surface area and high pseudocapacitance: Possible application in supercapacitors

2021 ◽  
Vol 319 ◽  
pp. 111063
Author(s):  
Yury M. Volfkovich ◽  
Valentin E. Sosenkin ◽  
Alexei Y. Rychagov ◽  
Alexandr V. Melezhik ◽  
Alexei G. Tkachev ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Material ◽  
High Specific Surface Area

Efficient conversion of CO2 to methane using thin-layer SiOx matrix anchored nickel catalysts

2019 ◽  
Vol 43 (33) ◽  
pp. 13217-13224 ◽  
Author(s):  
Xieyi Huang ◽  
Peng Wang ◽  
Zhichao Zhang ◽  
Shaoning Zhang ◽  
Xianlong Du ◽  
...  
Keyword(s):  
Thin Layer ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Geometric Structure ◽  
Nickel Catalysts ◽  
High Specific Surface Area ◽  
Efficient Conversion

Thin-layer SiOx matrix anchored nickel catalysts with high specific surface area and a unique electronic/geometric structure were fabricated for efficient CO2 methanation.

High specific surface area LaFeCo perovskites—Synthesis by nanocasting and catalytic behavior in the reduction of NO with CO

2009 ◽  
Vol 90 (3-4) ◽  
pp. 441-450 ◽  
Author(s):  
R.K.C. de Lima ◽  
M.S. Batista ◽  
M. Wallau ◽  
E.A. Sanches ◽  
Y.P. Mascarenhas ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Catalytic Behavior ◽  
Reduction Of No
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