Publications by authors named "Joseph Halim"

20 Publications

  • Page 1 of 1

Boridene: Two-dimensional MoB with ordered metal vacancies obtained by chemical exfoliation.

Science 2021 08;373(6556):801-805

Materials Design, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden.

Extensive research has been invested in two-dimensional (2D) materials, typically synthesized by exfoliation of van der Waals solids. One exception is MXenes, derived from the etching of constituent layers in transition metal carbides and nitrides. We report the experimental realization of boridene in the form of single-layer 2D molybdenum boride sheets with ordered metal vacancies, MoBT (where T is fluorine, oxygen, or hydroxide surface terminations), produced by selective etching of aluminum and yttrium or scandium atoms from 3D in-plane chemically ordered (MoY)AlB and (MoSc)AlB in aqueous hydrofluoric acid. The discovery of a 2D transition metal boride suggests a wealth of future 2D materials that can be obtained through the chemical exfoliation of laminated compounds.
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http://dx.doi.org/10.1126/science.abf6239DOI Listing
August 2021

Out-Of-Plane Ordered Laminate Borides and Their 2D Ti-Based Derivative from Chemical Exfoliation.

Adv Mater 2021 Sep 5;33(38):e2008361. Epub 2021 Aug 5.

Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-581 83, Sweden.

Exploratory theoretical predictions in uncharted structural and compositional space are integral to materials discoveries. Inspired by M SiB (T2) phases, the finding of a family of laminated quaternary metal borides, M' M″SiB , with out-of-plane chemical order is reported here. 11 chemically ordered phases as well as 40 solid solutions, introducing four elements previously not observed in these borides are predicted. The predictions are experimentally verified for Ti MoSiB , establishing Ti as part of the T2 boride compositional space. Chemical exfoliation of Ti MoSiB and select removal of Si and MoB sub-layers is validated by derivation of a 2D material, TiO Cl , of high yield and in the form of delaminated sheets. These sheets have an experimentally determined direct band gap of ≈4.1 eV, and display characteristics suitable for supercapacitor applications. The results take the concept of chemical exfoliation beyond currently available 2D materials, and expands the envelope of 3D and 2D candidates, and their applications.
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http://dx.doi.org/10.1002/adma.202008361DOI Listing
September 2021

Acoustomicrofluidic Synthesis of Pristine Ultrathin TiCT MXene Nanosheets and Quantum Dots.

ACS Nano 2021 Jun 29. Epub 2021 Jun 29.

Micro/Nanophysics Research Laboratory, RMIT University, Melbourne, VIC 3000, Australia.

The conversion of layered transition metal carbides and/or nitrides (MXenes) into zero-dimensional structures with thicknesses and lateral dimensions of a few nanometers allows these recently discovered materials with exceptional electronic properties to exploit the additional benefits of quantum confinement, edge effects, and large surface area. Conventional methods for the conversion of MXene nanosheets and quantum dots, however, involve extreme conditions such as high temperatures and/or harsh chemicals that, among other disadvantages, lead to significant degradation of the material as a consequence of their oxidation. Herein, we show that the large surface acceleration-on the order of 10 million 's-produced by high-frequency (10 MHz) nanometer-order electromechanical vibrations on a chip-scale piezoelectric substrate is capable of efficiently nebulizing, and consequently dimensionally reducing, a suspension of multilayer TiCT (MXene) into predominantly monolayer nanosheets and quantum dots while, importantly, preserving the material from any appreciable oxidation. As an example application, we show that the high-purity MXene quantum dots produced using this room-temperature chemical-free synthesis method exhibit superior performance as electrode materials for electrochemical sensing of hydrogen peroxide compared to the highly oxidized samples obtained through conventional hydrothermal synthesis. The ability to detect concentrations as low as 5 nM is a 10-fold improvement to the best reported performance of TiCT MXene electrochemical sensors to date.
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http://dx.doi.org/10.1021/acsnano.1c03428DOI Listing
June 2021

Ultrafast, One-Step, Salt-Solution-Based Acoustic Synthesis of TiC MXene.

ACS Nano 2021 Mar 26;15(3):4287-4293. Epub 2021 Feb 26.

Department of Physics, Chemistry, and Biology (IFM) Linköping University, SE-581 83 Linköping, Sweden.

The current quest for two-dimensional transition metal carbides and nitrides (MXenes) has been to circumvent the slow, hazardous, and laborious multistep synthesis procedures associated with conventional chemical MAX phase exfoliation. Here, we demonstrate a one-step synthesis method with local TiAlC MAX to TiCT MXene conversion on the order of milliseconds, facilitated by proton production through solution dissociation under megahertz frequency acoustic excitation. These protons combined with fluorine ions from LiF to selectively etch the MAX phase into MXene, whose delamination is aided by the acoustic forcing. These results have important implications for the future applicability of MXenes, which crucially depend on the development of more efficient synthesis procedures. For proof-of-concept, we show that flexible electrodes fabricated by this method exhibit comparable electrochemical performance to that previously reported.
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http://dx.doi.org/10.1021/acsnano.0c07242DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8034768PMC
March 2021

Flexible Free-Standing MoO/TiCT MXene Composite Films with High Gravimetric and Volumetric Capacities.

Adv Sci (Weinh) 2021 Feb 31;8(3):2003656. Epub 2020 Dec 31.

Department of Physics, Chemistry and Biology (IFM) Linköping University Linköping 581 83 Sweden.

Enhancing both the energy storage and power capabilities of electrochemical capacitors remains a challenge. Herein, TiCT MXene is mixed with MoO nanobelts in various mass ratios and the mixture is used to vacuum filter binder free, open, flexible, and free-standing films. The conductive TiCT flakes bridge the nanobelts, facilitating electron transfer; the randomly oriented, and interconnected, MoO nanobelts, in turn, prevent the restacking of the TiCT nanosheets. Benefitting from these advantages, a MoO/TiCT film with a 8:2 mass ratio exhibits high gravimetric/volumetric capacities with good cyclability, namely, 837 C g and 1836 C cm at 1 A g for an ≈ 10 µm thick film; and 767 C g and 1664 C cm at 1 A g for ≈ 50 µm thick film. To further increase the energy density, hybrid capacitors are fabricated with MoO/TiCT films as the negative electrodes and nitrogen-doped activated carbon as the positive electrodes. This device delivers maximum gravimetric/volumetric energy densities of 31.2 Wh kg and 39.2 Wh L, respectively. The cycling stability of 94.2% retention ratio after 10 000 continuous charge/discharge cycles is also noteworthy. The high energy density achieved in this work can pave the way for practical applications of MXene-containing materials in energy storage devices.
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http://dx.doi.org/10.1002/advs.202003656DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7856882PMC
February 2021

Tailored synthesis approach of (MoY)AlC i-MAX and its two-dimensional derivative MoCT MXene: enhancing the yield, quality, and performance in supercapacitor applications.

Nanoscale 2021 Jan 18;13(1):311-319. Epub 2020 Dec 18.

Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping, Sweden.

A vacancy-ordered MXene, MoCT, obtained from the selective etching of Al and Sc from the parent i-MAX phase (MoSc)AlC has previously shown excellent properties for supercapacitor applications. Attempts to synthesize the same MXene from another precursor, (MoY)AlC, have not been able to match its forerunner. Herein, we show that the use of an AlY alloy instead of elemental Al and Y for the synthesis of (MoY)AlC i-MAX, results in a close to 70% increase in sample purity due to the suppression of the main secondary phase, MoAlC. Furthermore, through a modified etching procedure, we obtain a MoCT MXene of high structural quality and improve the yield by a factor of 6 compared to our previous efforts. Free-standing films show high volumetric (1308 F cm) and gravimetric (436 F g) capacitances and a high stability (98% retention) at the level of, or even beyond, those reported for the MoCT MXene produced from the Sc-based i-MAX. These results are of importance for the realization of high quality MXenes through use of more abundant elements (Y vs. Sc), while also reducing waste (impurity) material and facilitating the synthesis of a high-performance material for applications.
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http://dx.doi.org/10.1039/d0nr07045aDOI Listing
January 2021

Composition Tuning of Nanostructured Binary Copper Selenides through Rapid Chemical Synthesis and their Thermoelectric Property Evaluation.

Nanomaterials (Basel) 2020 Apr 28;10(5). Epub 2020 Apr 28.

Department of Applied Physics, KTH Royal Institute of Technology, SE-106 91 Stockholm, Sweden.

Reduced energy consumption and environmentally friendly, abundant constituents are gaining more attention for the synthesis of energy materials. A rapid, highly scalable, and process-temperature-sensitive solution synthesis route is demonstrated for the fabrication of thermoelectric CuSe. The process relies on readily available precursors and microwave-assisted thermolysis, which is sensitive to reaction conditions; yielding CuSe at 200 °C and CuSe at 250 °C within 6-8 min reaction time. Transmission electron microscopy (TEM) revealed crystalline nature of as-made particles with irregular truncated morphology, which exhibit a high phase purity as identified by X-ray powder diffraction (XRPD) analysis. Temperature-dependent transport properties were characterized via electrical conductivity, Seebeck coefficient, and thermal diffusivity measurements. Subsequent to spark plasma sintering, pure CuSe exhibited highly compacted and oriented grains that were similar in size in comparison to CuSe, which led to its high electrical and low thermal conductivity, reaching a very high power-factor (24 µW/Kcm). Density-of-states (DOS) calculations confirm the observed trends in electronic properties of the material, where Cu-deficient phase exhibits metallic character. The TE figure of merit () was estimated for the materials, demonstrating an unprecedentedly high at 875 K of 2.1 for CuSe sample, followed by 1.9 for CuSe. Synthetic and processing methods presented in this work enable large-scale production of TE materials and components for niche applications.
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http://dx.doi.org/10.3390/nano10050854DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712069PMC
April 2020

Synthesis of (VSc)AlC i-MAX phase and VC MXene scrolls.

Nanoscale 2019 Aug;11(31):14720-14726

Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden.

We report the synthesis and characterization of a new laminated i-MAX phase, (V2/3Sc1/3)2AlC, with in-plane chemical ordering between the M-elements. We also present evidence for the solid solution (V2-xScx)2AlC, where x ≤ 0.05. Chemical etching of the Al and Sc results in a two-dimensional (2D) MXene counterpart: V2-xC from the latter phase. Furthermore, etching with HF yields single-sheet MXene of flat morphology, while LiF + HCl gives MXene scrolls. We also show a 4× reduction in etching time for (V2-xScx)2AlC compared to V2AlC, suggesting that traces of Sc changes the phase stability, and make the material more susceptible to etching. The results show a path for improved control of MXene synthesis and morphology, which may be applicable also for other MAX/MXene systems.
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http://dx.doi.org/10.1039/c9nr02354bDOI Listing
August 2019

Electronic and optical characterization of 2D TiC and NbC (MXene) thin films.

J Phys Condens Matter 2019 Apr 22;31(16):165301. Epub 2019 Jan 22.

Department of Physics, Chemistry and Biology (IFM), Thin Film Physics Division, Linköping University, SE-58183 Linköping, Sweden.

Two-dimensional (2D) transition metal carbides and/or nitrides (MXenes) are a new class of 2D materials, with extensive opportunities for property tailoring due to the numerous possibilities for varying chemistries and surface terminations. Here, TiAlC and NbAlC MAX phase epitaxial thin films were deposited on sapphire substrates by physical vapor deposition. The films were then etched in LiF/HCl solutions, yielding Li-intercalated, 2D TiCT and NbCT films, whose terminations, transport and optical properties were characterized. The former exhibits metallic conductivity, with weak localization below 50 K. In contrast, the Nb-based film exhibits an increase in resistivity with decreasing temperature from RT down to 40 K consistent with variable range hopping transport. The optical properties of both films were determined from spectroscopic ellipsometry in the 0.75 to 3.50 eV range. The results for TiCT films confirm the metallic behavior. In contrast, no evidence of metallic behavior is observed for the NbCT film. The present work therefore demonstrates that one fruitful approach to alter the electronic and optical properties of MXenes is to change the nature of the transition metal.
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http://dx.doi.org/10.1088/1361-648X/ab00a2DOI Listing
April 2019

A Tungsten-Based Nanolaminated Ternary Carbide: (W,Ti)C.

Inorg Chem 2019 Jan 4;58(2):1100-1106. Epub 2019 Jan 4.

Department of Materials Science and Engineering , Drexel University , Philadelphia , Pennsylvania 19104 , United States.

Nanolamellar transition metal carbides are gaining increasing interests because of the recent developments of their two-dimensional (2D) derivatives and promising performance for a variety of applications from energy storage, catalysis to transparent conductive coatings, and medicine. To develop more novel 2D materials, new nanolaminated structures are needed. Here we report on a tungsten-based nanolaminated ternary phase, (W,Ti)C, synthesized by an Al-catalyzed reaction of W, Ti, and C powders at 1600 °C for 4 h, under flowing argon. X-ray and neutron diffraction, along with Z-contrast scanning transmission electron microscopy, were used to determine the atomic structure, ordering, and occupancies. This phase has a layered hexagonal structure ( P6 /mmc) with lattice parameters, a = 3.00880(7) Å, and c = 19.5633(6) Å and a nominal chemistry of (W,Ti)C (actual chemistry, WTiC). The structure is comprised of layers of pure W that are also twin planes with two adjacent atomic layers of mixed W and Ti, on either side. The use of Al as a catalyst for synthesizing otherwise difficult to make phases, could in turn lead to the discovery of a large family of nonstoichiometric ternary transition metal carbides, synthesized at relatively low temperatures and shorter times.
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http://dx.doi.org/10.1021/acs.inorgchem.8b02226DOI Listing
January 2019

2D Transition Metal Carbides (MXenes) for Carbon Capture.

Adv Mater 2019 Jan 4;31(2):e1805472. Epub 2018 Nov 4.

Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83, Linköping, Sweden.

Global warming caused by burning of fossil fuels is indisputably one of mankind's greatest challenges in the 21st century. To reduce the ever-increasing CO emissions released into the atmosphere, dry solid adsorbents with large surface-to-volume ratio such as carbonaceous materials, zeolites, and metal-organic frameworks have emerged as promising material candidates for capturing CO . However, challenges remain because of limited CO /N selectivity and long-term stability. The effective adsorption of CO gas (≈12 mol kg ) on individual sheets of 2D transition metal carbides (referred to as MXenes) is reported here. It is shown that exposure to N gas results in no adsorption, consistent with first-principles calculations. The adsorption efficiency combined with the CO /N selectivity, together with a chemical and thermal stability, identifies the archetype Ti C MXene as a new material for carbon capture (CC) applications.
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http://dx.doi.org/10.1002/adma.201805472DOI Listing
January 2019

On the Structural Stability of MXene and the Role of Transition Metal Adatoms.

Nanoscale 2018 Jun;10(23):10850-10855

Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden.

In the present communication, the atomic structure and coordination of surface adsorbed species on Nb2C MXene is investigated over time. In particular, the influence of the Nb adatoms on the structural stability and oxidation behavior of the MXene is addressed. This investigation is based on the plane-view geometry observations of single Nb2C MXene sheets by a combination of atomic-resolution scanning transmission electron microscopy (STEM), electron energy loss spectroscopy (EELS) and STEM image simulations.
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http://dx.doi.org/10.1039/c8nr01986jDOI Listing
June 2018

W-Based Atomic Laminates and Their 2D Derivative W C MXene with Vacancy Ordering.

Adv Mater 2018 May 6;30(21):e1706409. Epub 2018 Apr 6.

Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83, Linköping, Sweden.

Structural design on the atomic level can provide novel chemistries of hybrid MAX phases and their MXenes. Herein, density functional theory is used to predict phase stability of quaternary i-MAX phases with in-plane chemical order and a general chemistry (W M ) AC, where M = Sc, Y (W), and A = Al, Si, Ga, Ge, In, and Sn. Of over 18 compositions probed, only two-with a monoclinic C2/c structure-are predicted to be stable: (W Sc ) AlC and (W Y ) AlC and indeed found to exist. Selectively etching the Al and Sc/Y atoms from these 3D laminates results in W C-based MXene sheets with ordered metal divacancies. Using electrochemical experiments, this MXene is shown to be a new, promising catalyst for the hydrogen evolution reaction. The addition of yet one more element, W, to the stable of M elements known to form MAX phases, and the synthesis of a pure W-based MXene establishes that the etching of i-MAX phases is a fruitful path for creating new MXene chemistries that has hitherto been not possible, a fact that perforce increases the potential of tuning MXene properties for myriad applications.
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http://dx.doi.org/10.1002/adma.201706409DOI Listing
May 2018

Tailoring Structure, Composition, and Energy Storage Properties of MXenes from Selective Etching of In-Plane, Chemically Ordered MAX Phases.

Small 2018 Apr 3;14(17):e1703676. Epub 2018 Apr 3.

Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83, Linköping, Sweden.

The exploration of 2D solids is one of our time's generators of materials discoveries. A recent addition to the 2D world is MXenes that possses a rich chemistry due to the large parent family of MAX phases. Recently, a new type of atomic laminated phases (coined i-MAX) is reported, in which two different transition metal atoms are ordered in the basal planes. Herein, these i-MAX phases are used in a new route for tailoriong the MXene structure and composition. By employing different etching protocols to the parent i-MAX phase (Mo Y ) AlC, the resulting MXene can be either: i) (Mo Y ) C with in-plane elemental order through selective removal of Al atoms or ii) Mo C with ordered vacancies through selective removal of both Al and Y atoms. When (Mo Y ) C (ideal stoichiometry) is used as an electrode in a supercapacitor-with KOH electrolyte-a volumetric capacitance exceeding 1500 F cm is obtained, which is 40% higher than that of its Mo C counterpart. With H SO , the trend is reversed, with the latter exhibiting the higher capacitance (≈1200 F cm ). This additional ability for structural tailoring will indubitably prove to be a powerful tool in property-tailoring of 2D materials, as exemplified here for supercapacitors.
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http://dx.doi.org/10.1002/smll.201703676DOI Listing
April 2018

Two-dimensional MoC MXene with divacancy ordering prepared from parent 3D laminate with in-plane chemical ordering.

Nat Commun 2017 04 25;8:14949. Epub 2017 Apr 25.

Thin Film Physics, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden.

The exploration of two-dimensional solids is an active area of materials discovery. Research in this area has given us structures spanning graphene to dichalcogenides, and more recently 2D transition metal carbides (MXenes). One of the challenges now is to master ordering within the atomic sheets. Herein, we present a top-down, high-yield, facile route for the controlled introduction of ordered divacancies in MXenes. By designing a parent 3D atomic laminate, (MoSc)AlC, with in-plane chemical ordering, and by selectively etching the Al and Sc atoms, we show evidence for 2D MoC sheets with ordered metal divacancies and high electrical conductivities. At ∼1,100 F cm, this 2D material exhibits a 65% higher volumetric capacitance than its counterpart, MoC, with no vacancies, and one of the highest volumetric capacitance values ever reported, to the best of our knowledge. This structural design on the atomic scale may alter and expand the concept of property-tailoring of 2D materials.
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http://dx.doi.org/10.1038/ncomms14949DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5413966PMC
April 2017

Two-Dimensional Titanium Carbide MXene As a Cathode Material for Hybrid Magnesium/Lithium-Ion Batteries.

ACS Appl Mater Interfaces 2017 Feb 8;9(5):4296-4300. Epub 2016 Jun 8.

Department of Materials Science and Engineering and A. J. Drexel Nanomaterials Institute, Drexel University , Philadelphia, Pennsylvania 19104, United States.

As an alternative to pure lithium-ion, Li, systems, a hybrid magnesium, Mg, and Li battery can potentially combine the high capacity, high voltage, and fast Li intercalation of Li-ion battery cathodes and the high capacity, low cost, and dendrite-free Mg metal anodes. Herein, we report on the use of two-dimensional titanium carbide, TiCT (MXene), as a cathode in hybrid Mg/Li batteries, coupled with a Mg metal anode. Free-standing and flexible TiCT/carbon nanotube composite "paper" delivered ∼100 mAh g at 0.1 C and ∼50 mAh g at 10 C. At 1 C the capacity was maintained for >500 cycles at 80 mAh g. The MoCT MXene also demonstrated good performance as a cathode material in this hybrid battery. Considering the variety of available MXenes, this work opens the door for exploring a new large family of 2D materials with high electrical conductivity and large intercalation capacity as cathodes for hybrid Mg/Li batteries.
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http://dx.doi.org/10.1021/acsami.6b04198DOI Listing
February 2017

Atomically Resolved Structural and Chemical Investigation of Single MXene Sheets.

Nano Lett 2015 Aug 27;15(8):4955-60. Epub 2015 Jul 27.

†Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden.

The properties of two-dimensional (2D) materials depend strongly on the chemical and electrochemical activity of their surfaces. MXene, one of the most recent additions to 2D materials, shows great promise as an energy storage material. In the present investigation, the chemical and structural properties of individual Ti3C2 MXene sheets with associated surface groups are investigated at the atomic level by aberration corrected STEM-EELS. The MXene sheets are shown to exhibit a nonuniform coverage of O-based surface groups which locally affect the chemistry. Additionally, native point defects which are proposed to affect the local surface chemistry, such as oxidized titanium adatoms (TiOx), are identified and found to be mobile.
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http://dx.doi.org/10.1021/acs.nanolett.5b00737DOI Listing
August 2015

Transparent Conductive Two-Dimensional Titanium Carbide Epitaxial Thin Films.

Chem Mater 2014 Apr 28;26(7):2374-2381. Epub 2014 Feb 28.

Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States ; Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University , SE-581 83, Linköping, Sweden.

Since the discovery of graphene, the quest for two-dimensional (2D) materials has intensified greatly. Recently, a new family of 2D transition metal carbides and carbonitrides (MXenes) was discovered that is both conducting and hydrophilic, an uncommon combination. To date MXenes have been produced as powders, flakes, and colloidal solutions. Herein, we report on the fabrication of ∼1 × 1 cm TiC films by selective etching of Al, from sputter-deposited epitaxial TiAlC films, in aqueous HF or NHHF. Films that were about 19 nm thick, etched with NHHF, transmit ∼90% of the light in the visible-to-infrared range and exhibit metallic conductivity down to ∼100 K. Below 100 K, the films' resistivity increases with decreasing temperature and they exhibit negative magnetoresistance-both observations consistent with a weak localization phenomenon characteristic of many 2D defective solids. This advance opens the door for the use of MXenes in electronic, photonic, and sensing applications.
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http://dx.doi.org/10.1021/cm500641aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3982936PMC
April 2014

Room-temperature carbide-derived carbon synthesis by electrochemical etching of MAX phases.

Angew Chem Int Ed Engl 2014 May 1;53(19):4877-80. Epub 2014 Apr 1.

A. J. Drexel Nanomaterials Institute, and Materials Science and Engineering Department, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (USA).

Porous carbons are widely used in energy storage and gas separation applications, but their synthesis always involves high temperatures. Herein we electrochemically selectively extract, at ambient temperature, the metal atoms from the ternary layered carbides, Ti3 AlC2 , Ti2 AlC and Ti3 SiC2 (MAX phases). The result is a predominantly amorphous carbide-derived carbon, with a narrow distribution of micropores. The latter is produced by placing the carbides in HF, HCl or NaCl solutions and applying anodic potentials. The pores that form when Ti3 AlC2 is etched in dilute HF are around 0.5 nm in diameter. This approach forgoes energy-intensive thermal treatments and presents a novel method for developing carbons with finely tuned pores for a variety of applications, such as supercapacitor, battery electrodes or CO2 capture.
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http://dx.doi.org/10.1002/anie.201402513DOI Listing
May 2014

New two-dimensional niobium and vanadium carbides as promising materials for Li-ion batteries.

J Am Chem Soc 2013 Oct 21;135(43):15966-9. Epub 2013 Oct 21.

Department of Materials Science & Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States.

New two-dimensional niobium and vanadium carbides have been synthesized by selective etching, at room temperature, of Al from Nb2AlC and V2AlC, respectively. These new matrials are promising electrode materials for Li-ion batteries, demonstrating good capability to handle high charge-discharge rates. Reversible capacities of 170 and 260 mA·h·g(-1) at 1 C, and 110 and 125 mA·h·g(-1) at 10 C were obtained for Nb2C and V2C-based electrodes, respectively.
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http://dx.doi.org/10.1021/ja405735dDOI Listing
October 2013
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