Two and three-dimensional (2D/3D) hybrid materials

  • By Leena Aggarwal
  • 19 January 2018

In the recently published paper in Journal of Nanoscale, Randall M. Feenstra and their colleagues have demonstrated the importance of 2D layer thickness and transition metal dichalcogenide (TMD) in the transport properties of the hybrid structure, where monolayer TMDs exhibit direct tunneling through the layer, while transport in few layer TMDs on GaN is dominated by p–n diode behavior and varies with the 2D/3D hybrid structure. They have shown the scalable synthesis of molybdenum disulfide (MoS2) and tungsten diselenide (WSe2) via metal organic chemical vapor deposition (MOCVD) on gallium nitride (GaN), and elucidated the structure, chemistry, and vertical transport properties of the 2D/3D hybrid.

Direct conversion of unsubstituted furan into benzene

  • By Leena Aggarwal
  • 16 January 2018

In the recently published paper in Journal of ACS Catalysis, Giannis Mpourmpakis and their colleagues have discussed the direct Catalytic Conversion of Biomass Derived Furan and Ethanol to Ethylbenzene. They have reported a synthetic strategy to convert biomass-derived unsubstituted furan to aromatics at high selectivity, especially to ethylbenzene via alkylation/Diels-Alder cycloaddition using ethanol, while greatly reducing the formation of the main side product, benzofuran, over zeolite catalysts.

Four-dimensional physics in two dimensions

  • By Leena Aggarwal
  • 5 January 2018

Kevin Chen and team have demonstrated that the behavior of particles of light can be made to match predictions about the four-dimensional version of the "quantum Hall effect"—a phenomenon that has been at the root of three Nobel Prizes in physics—in a two-dimensional array of "waveguides."

“For the first time, physicists have built a two-dimensional experimental system that allows them to study the physical properties of materials that were theorized to exist only in four-dimensional space"

Understanding of the superior stability of Silicon- and oxygen-containing hydrogenated amorphous carbon in harsh environments

  • By Leena Aggarwal
  • 3 January 2018

Recently, Tevis D. B. Jacobs and colleagues have shown how silicon- and oxygen-containing hydrogenated amorphous carbon (a-C:H:Si:O) coating enhance the thermal stability in vacuum, but tremendously increases the thermo-oxidative stability and the resistance to degradation upon exposure to the harsh conditions of low Earth orbit (LEO). These findings provide a novel physically-based understanding of the superior stability of a-C:H:Si:O in harsh environments compared to a-C:H.

New Catalyst That Advances Capture and Conversion of Atmospheric Carbon Dioxide

  • By Aude Marjolin
  • 7 December 2016

Karl Johnson CST cover imageResearch focused on developing a new catalyst that would lead to large-scale implementation of capture and conversion of carbon dioxide (CO2) was recently published in the Royal Society of Chemistry journal Catalysis Science & Technology. Principal investigator is Karl Johnson, and postdoctoral associate Jingyun Ye is lead author. The article “Catalytic Hydrogenation of CO2 to Methanol in a Lewis Pair Functionalized MOF” is featured on the cover of Catalysis Science & Technology vol. 6, no. 24 and builds upon Johnson’s previous research that identified the two main factors for determining the optimal catalyst for turning atmospheric CO2 into liquid fuel. The research was conducted using computational resources at the University’s Center for Simulation and Modeling. 

Snapshots of Proton Conduction Process in Water

  • By Aude Marjolin
  • 5 December 2016

Scientists Capture Snapshots of the Proton Conduction Process in Water

The motion of protons (positively charged H atoms) in water is associated with water’s conduction of electricity and is involved in many important processes including vision, signaling in biological systems, photosynthesis and, the operation of fuel cells. Both artificial photosynthetic systems and fuel cells are of growing interest for clean energy technologies. However, the details of how protons move in water have remained elusive, and an enhanced understanding of the nature of this process is needed to improve the technologies that depend on proton transfer.

An international team of scientists, including a University of Pittsburgh professor and graduate student, has used spectroscopic methods to obtain snapshots of the process by which a proton is relayed from one water molecule to the next. The research is published in a paper in the December 2, 2016 issue of the journal Science.

Investigating Bond-Breaking in Unstrained Rings with Quantum Chemistry

  • By Aude Marjolin
  • 9 November 2016

Although synthetic chemists typically regard carbon-carbon single bonds as inert, they have used metal catalysts to spring open C–C bonds in strained rings, such as cyclopropanes and cyclobutanes. Performing a similar transformation with less strained but more common five- and six-membered rings, however, has proven more difficult.

Now, synthetic and theoretical chemists report a way of opening up C–C bonds in aryl substituted cyclopentanones to produce α-tetralones. The reaction was developed by University of Chicago’s Guangbin Dong and Ying Xia, and at Pitt, Peng Liu and his post doc Gang Lu studied the mechanism from a quantum chemical point of view with DFT (Density Functional Theory) calculations.

The results are published in the online issue of Nature.

The Calisthenics of Surface Femtochemistry

  • By Aude Marjolin
  • 27 October 2016

Application of a femtosecond spectroscopy technique to a copper surface has allowed the desorption of carbon monoxide molecules to be tracked with unprecedented detail.

In this view point article, Hrvoje Petek comments on the work of Ken-ichi Inoue et al. on the multidimensional nonequilibrium dynamics of CO as it desorbs from a Cu(100) surface.  He opens by saying that "it has long been a chemist’s dream to catch a chemical reaction in the act", with the aim "to observe and interfere with this process in mid-course and thereby control its outcome".

Quantum Chemistry Helps Identify New Treatment to Prevent Kidney Stones

  • By Aude Marjolin
  • 15 August 2016

A natural citrus fruit extract has been found to dissolve calcium oxalate crystals, the most common component of human kidney stones, in a finding that could lead to significantly improving kidney stone treatment, according to researchers at the University of Pittsburgh, the University of Houston, and Litholink Corporation, among which is Giannis Mpourmpakis.

In a study published Aug. 8 in the journal Nature, the researchers offer the first evidence that the compound hydroxycitrate (HCA) effectively inhibits calcium oxalate crystal growth and, under certain conditions, is able to dissolve the crystals. HCA shows “promise as a potential therapy to prevent kidney stones,” the researchers wrote. 

Spin Selective Charge Transport in Quantum Dots

  • By Aude Marjolin
  • 21 July 2016

The latest study in David Waldeck's group, published in ACS Nano Letters, demonstrates that chiral imprinted CdSe quantum dots (QDs) can act as spin selective filters for charge transport.

Semiconductor quantum dots remain an attractive material for photovoltaics because of their solution processability and potential for multiple exciton generation; enabling a promising route for the realization of low cost, high efficiency solar cells. In addition, previous experiments have shown that spin selective charge transport can enhance the photoconversion efficiencies of organic bulk heterojunctions. The present work therefore explores whether chiral induced spin selectivity (CISS) can be used as an alternative approach to affect charge transport through quantum dot films and demonstrates that quantum dot thin films composed of chiral semiconductors preferentially transmit electrons with a particular spin orientation.