http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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>
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>
Byeon, Ayeong,Hatter, C.B.,Park, Jae H.,Ahn, Chi W.,Gogotsi, Yury,Lee, Jae W. Elsevier 2017 ELECTROCHIMICA ACTA Vol.258 No.-
<P><B>Abstract</B></P> <P>Multilayer Mo<SUB>2</SUB>CT<SUB>x</SUB> MXene is used as a precursor to produce molybdenum oxide (MoO<SUB>2</SUB>)-disordered carbon hybrid materials using a one-step CO<SUB>2</SUB> oxidation. The composites show clear, short plateaus in the charge/discharge curves as well as reversible phase transition peaks in cyclic voltammetry for the resulting MoO<SUB>2</SUB>. The electrochemical measurements support the generation of the metal oxide in the resulting composite materials. The generation of molybdenum oxide from Mo<SUB>2</SUB>CT<SUB>x</SUB> is verified from the plateau in Li<SUP>+</SUP> charge-discharge profile as wells as various characterizations of XRD, XPS, etc. The resulting MoO<SUB>2</SUB> active material coated on a copper foil shows a Li-ion capacity of 323 mAh/g at 50 mA/g (0.1 C) and 180 mAh/g at 1 A/g (4.0 C) with 85% retention for approximately 300 cycles.</P>
High mass loading, binder-free MXene anodes for high areal capacity Li-ion batteries
Kim, Seon Joon,Naguib, Michael,Zhao, Mengqiang,Zhang, Chuanfang,Jung, Hee-Tae,Barsoum, Michel W.,Gogotsi, Yury Elsevier 2015 ELECTROCHIMICA ACTA Vol.163 No.-
<P><B>Abstract</B></P> <P>Though anodes with high Li gravimetric capacities, beyond commercial graphite, have been intensively studied, gravimetric capacity does not precisely reflect the performance of a packed cell. Li anodes with high mass loadings, which can achieve high areal capacities, are required for many commercial applications. Herein, anodes with high mass loadings were fabricated using two-dimensional transition metal carbides (MXenes). Powders of the latter were cold pressed, without binders, at a pressure of 1GPa, to create ∼300μm thick, free-standing discs. When Ti<SUB>3</SUB>C<SUB>2</SUB> was used as the anode for lithium, the initial reversible areal capacity was ∼15mAh/cm<SUP>2</SUP>, which decreased to 5.9mAh/cm<SUP>2</SUP> after 50 cycles, but the decrease after the first ∼20 cycles was very gradual. The latter is one of the highest values ever reported to date. When Nb<SUB>2</SUB>C was used as the anode instead, the initial reversible capacity was ∼16mAh/cm<SUP>2</SUP>; this value decreased to 6.7mAh/cm<SUP>2</SUP> after 50 cycles, which is about a 14% increase compared to Ti<SUB>3</SUB>C<SUB>2</SUB>. As the research on MXenes for lithium ion batteries has just begun, there is certainly room for further improving their electrochemical performance.</P>