Researchers at the University of California, Los Angeles (UCLA), the University of Texas at Austin, and Hunan University (China) have recently devised a new method of preparing highly uniform, solution-processable, phase-pure semiconducting nanosheets. Their approach, outlined in a paper published in Nature, involves the electrochemical intercalation of quaternary ammonium molecules into 2-D crystals, followed by a mild sonication and exfoliation process.
The team reported on a new on-chip "tool" that helps to "see" & identify the key process that hinders the performance of catalyst used in fuel cells. The tool will help scientists find respective solutions more efficiently.
The work was led by Xiangfeng Duan, a UCLA professor of chemistry and biochemistry, and Yu Huang, a UCLA professor of materials science and engineering.
The lead author of the study is Mengning Ding (pictured right), a former UCLA CNSI postdoctoral fellow advised by Huang and Duan, now a professor of chemistry at Nanjing University, China. Other study authors are UCLA graduate students and postdoctoral researchers in Duan and Huang’s research groups and researchers from King Saud University, Saudi Arabia.
Chosen from a pool of 286 nominated promising scientific researchers aged 42 years and younger from America’s top academic and research institutions, Duan is one of 11 Physical Sciences & Engineering finalists and Garg is one of ten Chemistry finalists. The finalists were selected based on their extraordinary accomplishments and their promise for the future.
UCLA scientists and engineers have developed a new process for assembling semiconductor devices. The advance could lead to much more energy-efficient transistors for electronics and computer chips, diodes for solar cells and light-emitting diodes, and other semiconductor-based devices.
Thirty UCLA faculty members are among the most influential researchers in their fields for 2017, as determined by Claritive Analytics. The organization compiled its 2017 Highly Cited Researchers list of more than 3,000 scientists from around the world whose studies were among the top 1 percent most referenced in studies from their field. (Read more about the rankings methodology.)
A research team led by UCLA scientists and engineers has developed a method to make new kinds of artificial “superlattices” — materials comprised of alternating layers of ultra-thin “two-dimensional” sheets, which are only one or a few atoms thick. Unlike current state-of-the art superlattices, in which alternating layers have similar atomic structures, and thus similar electronic properties, these alternating layers can have radically different structures, properties and functions, something not previously available.
Researchers in the US and Saudi Arabia are the first to have observed negative transconductance (NTC) inside multilayer molybdenum-disulphide (MoS2) transistors with optimized graphene/metal hybrid contacts. The NTC behaviour comes about thanks to competition between inter-layer charge transport and charge transport through a vertical potential barrier in the MoS2. This unique effect could be exploited for making frequency doublers and phase-shift keying circuits with only one multilayer transistor – something that would greatly simplify circuit design compared to conventional technology, says the team.
An international team led by researchers at UCLA and Caltech has demonstrated how altering the form of platinum nanoscale wires from a smooth surface to a jagged one could dramatically reduce the amount of precious metal used as catalysts in fuel cells and lower the cost.
Researchers at UCLA’s California NanoSystems Institute have developed a dramatically advanced tool for analyzing how chemicals called nanocatalysts convert chemical reactions into electricity. Current spectroscopy methods require large laboratory machines to measure chemical reactions, but the new technique uses a nanoelectronic chip to do the same thing while the reactions are taking place — which previously was very difficult — with better accuracy, and while gathering a completely new set of data.
Electrodes containing porous graphene and a niobia composite could help improve electrochemical energy storage in batteries. This is the new finding from researchers at the University of California at Los Angeles who say that the nanopores in the carbon material facilitate charge transport in a battery. By fine tuning the size of these pores, they can not only optimize this charge transport but also increase the amount of active material in the device, which is an important step forward towards practical applications.
Researchers at the University of California, Los Angeles, have succeeded in minimizing both the contact resistance and channel length in transistors made from the 2D semiconductor molybdenum disulphide, so making a device that has a high ON current of 0.83 mA/µm at 300K. This new work shows for the first time that 2D semiconducting transistors can compete with silicon-based ones in terms of performance – as defined by the International Technology Roadmap for Semiconductors (ITRS).
Researchers in China and the US have unveiled the first nanoscale amplifier for light at the technologically important telecommunications wavelength of 1.55 µm (or the near-infrared). The new device, which is 20 times more powerful than previous such amplifiers that measured microns across, is small enough to fit on an integrated circuit. This means that it could help make for the next generation of faster, more efficient, nanophotonics components. [via nanotechweb and APS]
How can the electrodes of batteries be made more efficient? In the journal Angewandte Chemie, American scientists describe a powerful approach that uses solvated graphene frameworks as the anode material. Assembled in a lithium coin cell, the as-made electrode excelled with capacities surpassing the values of typically used graphite. [via nanowerk.com]
Researchers have fabricated field effect transistors made from molybdenum sulfide that demonstrated the best performance to date in a transistor of this type. In the near future, their invention could mean vastly more powerful and sensitive fitness and health trackers, smartphones, computer-interface eyewear and other wearable applications. [via newsroom.ucla]
A new way to grow 2D-layered semiconductor heterostructures whose composition can be controlled by modulating the constituent vapour-phase reactants during growth has been developed, producing single crystals and might be used to make a host of electronics devices, ranging from complementary logic circuits, photovoltaics and photodetectors, to light-emitting diodes and laser diodes. [via nanotechweb.org]
Researchers at the California NanoSystems Institute (CNSI) at UCLA have set the stage for a watershed in mobile energy storage by using a special graphene material to significantly boost the energy density of electrochemical capacitors, putting them on a par with lead acid batteries. [via newsroom.ucla]
The Beilby Medal and Prize is awarded annually to a scientist or engineer to recogise substantial work of exceptional practical significance in applied materials science, chemical engineering, energy efficiency or a related field. [via chem.ucla]