Danylo Zherebetskyy and his colleagues at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) found unexpected traces of water in semiconducting nanocrystals.
The water as a source of small ions for the surface of colloidal lead sulfide (PbS) nanoparticles allowed the team to explain just how the surface of these important particles are passivated, meaning how they achieve an overall balance of positive and negative ions. This has been a big question for some fifteen years, and the answer washes up in hydroxyl groups from water that had been thought...
Viruses are the enigma of the biological world – despite having their own DNA and being able to adapt to their environment and evolve, they are not considered to be alive like cells. In order to reproduce and multiply – a requirement of “life” – a virus must invade a living cell, eject its DNA into that of the cell, and commandeer the cell’s biological machinery. While a virus, essentially, may be nothing more than a dollop of DNA packed into a protective coating of protein called a capsid, the packaging of that DNA is critical. The molecular motors that drive this DNA packaging process,...
Graphene continues to reign as the next potential superstar material for the electronics industry, a slimmer, stronger and much faster electron conductor than silicon. With no natural energy band-gap, however, graphene’s superfast conductance can’t be switched off, a serious drawback for transistors and other electronic devices. Various techniques have been deployed to overcome this problem with one of the most promising being the integration of ultrathin layers of graphene and boron nitride into two-dimensional heterostructures. As conductors, these bilayered hybrids are almost as fast as...
Steve Forbes recently invited Lab Director Paul Alivisatos, the secretary of the U.S. Department of Agriculture, the governors of Indiana and Michigan, and the former governor of Virginia, to participate in a panel discussion moderated by Forbes at the recent 2014 Reinventing America Summit. In his comments, Alivisatos emphasized that Berkeley Lab and the DOE National Lab system are very successful in dual roles: continuing the great tradition of groundbreaking discovery science, while embracing a new role of enabling...
A pathway to more effective and efficient synthesis of pharmaceutical drugs and other flow reactor chemical products has been opened by a study in which for the first time the catalytic reactivity inside a microreactor was mapped in high resolution from start-to-finish. The results not only provided a better understanding of the chemistry behind the catalytic reactions, they also revealed opportunities for optimization, which resulted in better catalytic performances. The study was conducted by a team of scientists with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National...
The drive to develop ultrasmall and ultrafast electronic devices using a single atomic layer of semiconductors, such as transition metal dichalcogenides, has received a significant boost. Researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have recorded the first observations of a strong nonlinear optical resonance along the edges of a single layer of molybdenum disulfide. The existence of these edge states is key to the use of molybdenum disulfide in nanoelectronics, as well as a catalyst for the hydrogen evolution reaction in fuel...
A big step in the development of next-generation fuel cells and water-alkali electrolyzers has been achieved with the discovery of a new class of bimetallic nanocatalysts that are an order of magnitude higher in activity than the target set by the U.S. Department of Energy (DOE) for 2017. The new catalysts, hollow polyhedral nanoframes of platinum and nickel, feature a three-dimensional catalytic surface activity that makes them significantly more efficient and far less expensive than the best platinum catalysts used in today’s fuel cells and alkaline electrolyzers. This research was a...
If the chemical bonds that hold together the constituent atoms of a molecule could be tuned to become stronger or weaker, certain chemical properties of that molecule might be controlled to great advantage for applications in energy and catalysis. Berkeley Lab researchers at the Molecular Foundry, in collaboration with researchers from Rice University, were able to accomplish this feat by using an applied voltage and electric current to tune the strength of chemical bonds in fullerene or “buckyball” molecules. The softening of the buckyball chemical bonds was revealed by measured changes...
Two components of the RNA polymerase (RNAP) catalytic center, the bridge helix and the trigger loop (TL), have been linked with changes in elongation rate and pausing. Here, single molecule experiments with the WT and two TL-tip mutants of the Escherichia coli enzyme reveal that tip mutations modulate RNAP's pause-free velocity, identifying TL conformational changes as one of two rate-determining steps in elongation. Consistent with this observation, we find a direct correlation between helix propensity of the modified amino acid and pause-free velocity. Moreover, nucleotide analogs...
Integration of molybdenum disulfide (MoS2) onto high surface area photocathodes is highly desired to minimize the overpotential for the solar-powered hydrogen evolution reaction (HER). Semiconductor nanowires (NWs) are beneficial for use in photoelectrochemistry because of their large electrochemically available surface area and inherent ability to decouple light absorption and the transport of minority carriers. Here, silicon (Si) NW arrays were employed as a model photocathode system for MoS2 wrapping, and their solar-driven HER...