As part of an annual trip organized by Materials Advantage, Nanomaterials Group doctoral candidate Boris Dyatkin visited Washington, DC for Congressional Visits Day to advocate for STEM education. Read more about the trip at the Drexel MSE website.
Dr. Vadym Mochalin, a Research Associate Professor with the Nanomaterials Group, has accepted an invitation to join the Editorial Board for the prestigious Scientific Reports.
Scientific Reports was launched in mid 2011 by the Nature Publishing Group, the publishers of Nature. It is hosted on nature.com and available to the public, publishing original research papers of interest to specialists within a given field in the natural sciences. Mochalin will serve an initial two-year term as a member of the editorial board.
Mochalin leads nanodiamond research for the Nanomaterials Group, and is the author of more than 40 peer-reviewed publications and 8 international patents on nanodiamond, carbon nanoonions, graphene nanoscrolls, nanotubes, energy storage systems, composites, photocatalysis, modeling of materials, and thermodynamics of solutions.
Researchers in the Nanomaterials Group recently reported on the discovery of a new family of two-dimensional materials called “MXenes.” The materials’ structures are similar to graphene, with which they share many properties, including good electrical conductivity and potential applications in energy storage. Now, in a new paper in Nature Communications, Drexel researchers have demonstrated several new possible avenues for practical applications of MXenes.
MXenes are transition metal carbides and nitrides, created by selectively removing aluminum from layered ternary carbides known as MAX phases. Through this exfoliation process, the carbide layers are separated into two MXene sheets just a few atoms thick. MXenes can accommodate various ions and molecules between their layers by a process known as intercalation, which is sometimes a necessary step in order to exploit the materials’ unique properties. For example, placing lithium ions between MXene sheets has been shown to render them promising materials for both lithium-ion batteries and electrochemical capacitors.
Computational studies have suggested that fully exfoliating, or delaminating, certain MXenes would yield layers with exceptional charge capacities for use in battery anodes. To date, however, large-scale delamination had not been achieved. In “Intercalation and Delamination of Layered Carbides and Cabonitrides,” the Drexel team reports on successful intercalation of MXenes with several organic molecules, including dimethyl sulfoxide (DMSO), which allowed them to fully exfoliate stacked layers into MXene sheets and ultimately create MXene “paper” by filtering flakes from solution. This flexible and electrically conductive “paper” showed a lithium ion capacity of four times that of typical MXene material, with extremely high charging rates and a cyclability superior to graphite, which is used in commercial lithium-ion batteries. Critically, this work demonstrates that such material can be synthesized on a large scale.
Much attention has recently been drawn to two-dimensional – in other words, atomically thin – materials for which the sheet width is about 10,000 times larger than its thickness. Graphene is just one representative of a large group of two-dimensional solids, and MXenes add a dozen new members to the family that have unusual properties dictated by their structure and presence of various transition metals: for example, combining metallic electrical conductivity with hydrophylicity (good wetting). This new finding further expands the potential uses of the new materials.
“By demonstrating chemical intercalation of organic molecules between MXene layers, we have substantially altered properties of MXenes,” says Dr. Yury Gogotsi, whose Nanomaterials Group led the research in partnership with Dr. Michel Barsoum. “By separating MXene sheets via intercalation, we produced excellent materials for electrodes of batteries and electrochemical capacitors. We are currently exploring several other exciting applications and we firmly believe that this is just the beginning of an exciting road towards discovery of new MXene structures and finding applications in which they can outperform other materials.”
The researchers note that successful delamination of MXenes also creates opportunities in composites, catalysis, sensors, and sorption applications.
O. Mashtalir, M. Naguib, V.N. Mochalin, Y. Dall’Agnese, M. Heon, M.W. Barsoum, Y. Gogotsi. Intercalation and Delamination of Layered Carbides and Carbonitrides. Nature Communications, 4/16/13. 10.1038/ncomms2664
Amanda Pentecost, a BS/PhD student in the Nanomaterials Group, has been awarded a 2013 National Science Foundation Graduate Research Fellowship.
Pentecost has already published two journal papers based on nanodiamond research performed as an undergraduate member of the Nanomaterials Group. In winning the award, she joins NMG members Kelsey Hatzell and Kristy Jost, who were named as winners in 2012.
NSF made 2,000 award offers from more than 13,000 submitted applications. A full list of the 2013 Fellows can be found here.
“Adsorption of proteins in channels of carbon nanotubes: Effect of surface chemistry,” featuring work by Vadym Mochalin, Maria Lukatskaya, and NMG alum Volker Presser, has been published in the March 2013 volume of Materials Express.
Kristy Jost, a PhD candidate in the Nanomaterials Group, has been named a Graduate Student Award winner for the 2013 Lindau Meeting.
The Lindau Award supports exceptional doctoral student researchers to attend the annual Lindau Meeting of Nobel Laureates in Lindau, Germany each June. This year’s meeting (to be held June 30-July 5, 2013) will be focused on Chemistry and Chemistry-related fields. Jost works on developing “smart” and electronic textiles by combining high-tech fashion design techniques with advanced materials and nanotechnology, focusing primarily on integrated textile energy storage.
At the meeting, Laureates lecture on the topic of their choice in the mornings and participate in less formal, small-group discussions with the students in the afternoons and some evenings. A list of the participating Nobel Laureates can be found on the Lindau website.
Jost will be the fifth Drexel student to attend a Lindau meeting, and the second from Materials Science & Engineering.
Many people can relate to the hardship of starting a vehicle during a bitter cold morning before work. It takes a huge amount of power relative to a warm sunny day for two reasons: the mechanical parts of an engine require more power to start moving when cold (motor oil becomes viscous, like honey), and the battery operates at a very low efficiency because the ions in electrolyte solution move much slower at freezing temperatures.
A collaboration between researchers at Drexel University in Philadelphia, The University of Texas at Austin, and Paul Sabatier University in Toulousse, France have recently engineered a supercapacitor system that can operate efficiently at very low temperatures – as low as -50 °C (-58 °F). Just published in the journal Nano Energy, their work involves a unique nanostructured carbon material deemed activated microwave exfoliated graphite oxide (“a-MEGO”), which was inspired by the recent interest in graphene. Graphene, which is an atomically thin layer of carbon, has many applications in energy storage and generation.
Combined with a-MEGO is an electrolyte called an ionic liquid. These are salts like sodium chloride, but are liquid at room temperature or below. The a-MEGO material has a high surface area, with about 2 grams having the surface area of a football field; as a result, a-MEGO is able to store a large amount of charge on its surface as a supercapacitor. The unique electrolyte, which is a mixture of ionic liquids, allows for operation at low temperature. Commercial supercapacitors, by comparison, use an electrolyte that will fail at temperatures below -25 °C (-13 °F). Finally, supercapacitors will last for more than 10 years and up to 1 million charge/discharge cycles, compared to batteries that will last a couple years for about 1 thousand cycles. Imagine never having to change your car battery!
This study reinforces the potential of graphene in energy storage applications, but also demonstrates that only the right combination of an electrode material and an electrolyte leads to truly outstanding performance. This opens the door to development of even better supercapacitors using safe and non-flammable ionic liquid electrolytes.
Citation: Lin, R.; Tsai, W.- Y.; Murali, S.; Zhang, L. L.; McDonough, J. K.; Ruoff, R. S.; Taberna, P.- L.; Gogotsi, Y.; and Simon, P. Outstanding Performance of Activated Graphene Based Supercapacitors in Ionic Liquid Electrolyte from -50 to 80°C. Nano Energy, 2013, doi 10.1016/j.nanoen.2012.11.006
What? – Engineered a material / electrolyte supercapacitor system to store a large amount of energy at extremely low temperatures. Additionally, the system has a fast response rate and a high efficiency compared to batteries.
When? – First published online (Nano Energy).
Where? Collaboration between UTexas at Austin, Paul Sabatier University in Toulousse France, and Drexel University in Philadelphia.
Why? Present systems to power technology at very low temperatures, i.e. starting a vehicle in an Alaskan morning, require oversized batteries that have a very low efficiency and short lifetime. Our supercapacitor system delivers the most energy at a low temperature of -50 °C (-58 °F) and can operate for ~1 million charge / discharge cycles.
How? A unique carbon nanomaterial, activated microwave exfoliated graphite oxide (a-MEGO), was combined with a eutectic mixture of ionic liquids. The a-MEGO has a high surface area and allows for a large amount of charge to be stored capacitively on its surface, while the mixture of ionic liquids has a very low melting point and a wide voltage stability window.
Work by NMG alumni Volker Presser and Sun-Hwa Yeon is featured in Live Science: Nanoporous Carbon Materials Raise Chances of Surviving Sepsis. The researchers discuss their work on mesoporous carbons derived from silicon carbide-based ceramics for ultimate use in filtering cytokines from the blood to treat sepsis. The work was first published as the cover article in the November 2012 issue of Advanced Healthcare Materials.
Congratulations to Riju Singhal, who successfully defended his PhD thesis, “Carbon Nanotube Based Devices for Intracellular Analysis”!
Click here to read Riju’s abstract.
Min Hoen and NMG alum Volker Presser have published a paper in collaboration with the FIRST EFRC team at Oak Ridge National Laboratory. “In situ tracking of the nanoscale expansion of porous carbon electrodes” can be found in Energy and Environmental Science.