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Dispersions of Two-Dimensional Titanium Carbide MXene in Organic Solvents
Maleski, Kathleen,Mochalin, Vadym N.,Gogotsi, Yury American Chemical Society 2017 Chemistry of materials Vol.29 No.4
<P>Two-dimensional titanium carbide (Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB>) MXene has attracted a great deal of attention in the research community and has already showed promise in numerous applications, but only its dispersions in aqueous solutions have previously been available. Here we show that Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB> can be dispersed in many polar organic solvents, but the best dispersions were achieved in <I>N</I>,<I>N</I>-dimethylformamide, <I>N</I>-methyl-2-pyrrolidone, dimethyl sulfoxide, propylene carbonate, and ethanol. The dispersions were examined by measuring the concentration and absorbance spectra of MXene in organic solvents as well as correlating the concentration to solvent physical properties, such as surface tension, boiling point, and polarity index. Hildebrand and Hansen solubility parameters were additionally used to provide an initial understanding of how Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB> MXene behaves in organic media and potentially develop quantitative correlations to select solvents and their combinations that can disperse Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB> and other MXenes. Using this analysis, we have outlined a range of organic solvents, which can disperse Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB>, expanding the opportunities for processing techniques, such as mixing MXenes with other nanomaterials or polymers to form composites, preparing inks for printing, and deposition requiring solution processable materials, allowing the use of Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB> in a multitude of applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2017/cmatex.2017.29.issue-4/acs.chemmater.6b04830/production/images/medium/cm-2016-048307_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm6b04830'>ACS Electronic Supporting Info</A></P>
Carbide-derived-carbons with hierarchical porosity from a preceramic polymer
Yeon, S.H.,Reddington, P.,Gogotsi, Y.,Fischer, J.E.,Vakifahmetoglu, C.,Colombo, P. Pergamon Press ; Elsevier Science Ltd 2010 Carbon Vol.48 No.1
Synthesis of carbon by extraction of metals from carbides has been successfully used to produce a variety of micro-porous carbide-derived carbons (CDCs) with narrow pore size distributions and tunable sorption properties. This approach is of limited use when larger mesopores are targeted, however, because the relevant synthesis conditions yield broad pore size distributions. Here we demonstrate the porosity control in the 3-10nm range by employing preceramic polymer-derived silicon carbonitride (SiCN) precursors. Polymer pyrolysis in the temperature range 600-1400<SUP>o</SUP>C prior to chlorine etching yields disordered or graphitic CDC materials with surface area in the range 800-2400m<SUP>2</SUP>g<SUP>-1</SUP>. In the hierarchical pore structure formed by etching SiCN ceramics, the mesopores originate from etching silicon nitride (Si<SUB>3</SUB>N<SUB>4</SUB>) nano-sized crystals or amorphous Si-N domains, while the micropores come from SiC domains. The etching of polymer-derived ceramics allows synthesis of porous materials with a very high specific surface area and a large volume of mesopores with well controlled size, which are suitable for applications as sorbents for proteins or large drug molecules, and supports for metal catalyst nanoparticles.
이득용,김대준,박노진,Lee, Deuk-Yong,Gogotsi, George A.,Kim, Dae-Joon,Park, No-Jin 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.2
3Y-TZP에 희토류 산화물($CeO_2,\;Tb_2O_3$)을 0.5% 이하로 첨가시킨 지르코니아 단결정을 skull melting법으로 제조하여 오토클레이브 하에서 열수 상 안정성을 조사하였다. 극점도 측정결과, skull melting 법으로 제조한 $CeO_2$와 $Tb_2O_3$가 첨가된 시편들은 단결정이었으며 150∼250$^{\circ}C$에서 5시간 수증기 분위기 하에서 열처리한 후에도 정방정 상이 유지되는 우수한 열수 상 안정성이 관찰되었다. 3mol% $Y_2O_3$ Partially-Stabilized Zirconia single Crystals (PSZCs) containing a small quantity (<0.5%) of rare-earth oxides ($CeO_2,\;Tb_2O_3$) were prepared by using a direct high-frequency skull melting technique to evaluate hydrothermal stability in an autoclave. Pole exhibited no $t{\rightarrow}m$ phase transformation during aging for 5h at temperatures from 150 to 250$^{\circ}C$ and 4MPa water vapor pressure in an autoclave, resulting in excellent hydrothermal stability.
Alhabeb, Mohamed,Maleski, Kathleen,Anasori, Babak,Lelyukh, Pavel,Clark, Leah,Sin, Saleesha,Gogotsi, Yury American Chemical Society 2017 Chemistry of materials Vol.29 No.18
<P>Two-dimensional (2D) transition metal carbides, carbonitrides, and nitrides (MXenes) were discovered in 2011. Since the original discovery, more than 20 different compositions have been synthesized by the selective etching of MAX phase and other precursors and many more theoretically predicted. They offer a variety of different properties, making the family promising candidates in a wide range of applications, such as energy storage, electromagnetic interference shielding, water purification, electrocatalysis, and medicine. These solution-processable materials have the potential to be highly scalable, deposited by spin, spray, or dip coating, painted or printed, or fabricated in a variety of ways. Due to this promise, the amount of research on MXenes has been increasing, and methods of synthesis and processing are expanding quickly. The fast evolution of the material can also be noticed in the wide range of synthesis and processing protocols that determine the yield of delamination, as well as the quality of the 2D flakes produced. Here we describe the experimental methods and best practices we use to synthesize the most studied MXene, titanium carbide (Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB>), using different etchants and delamination methods. We also explain effects of synthesis parameters on the size and quality of Ti<SUB>3</SUB>C<SUB>2</SUB>T<SUB><I>x</I></SUB> and suggest the optimal processes for the desired application.</P> [FIG OMISSION]</BR>