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Research Highlights

2014

Life-cycle net energy assessment of large-scale hydrogen production via photoelectrochemical water splitting

This article reports the first prospective life-cycle net energy assessment of a utility-scale photoelectrochemical (PEC) hydrogen production facility including balance-of-system components. more»

Nonlinear Propagation in Optical Zero-Index Materials

The Subwavelength Metamaterials Program achieved the first experimental observation of nonlinear light generation from 3D metamaterials with zero refractive index: light gains strength in all directions while moving through the material. more»

Visualization of Electrode-Electrolyte Interfaces in LiPF6/EC/DEC Electrolyte for Lithium Ion Batteries via In-Situ TEM

Via in-situ electrochemical liquid cell transmission electron microscope (TEM), electrochemical reaction dynamics at the electrolyte-electrode interfaces are visualized in commercial electrolyte for lithium ion batteries. more»

Quantum Dot-Organic Semiconductor Hybrid: Using Energy Level Alignment for Efficient Carrier Transport

The Inorganic/Organic Nanocomposites Program has, for the first time, demonstrated efficient charge carrier transport modulation in quantum dot (QD) films by energy level alignment between QDs and ligands. more»

Nanoframes with 3D Electrocatalytic Surfaces

Synthesized nanoframes that allow 3D molecular accessibility to platinum-rich surfaces, achieving electrocatalyst with high surface-to-volume ratio and control of surface chemistry. more»

2013

A Square Peg in a Round Hole: Nanocrystals Pass Through Tiny Constrictions Unchanged

A team of researchers have observed an iron nanocrystal move through a constriction in a carbon nanotube with a smaller diameter than that of the nanocrystal, driven by an electric current. It's the nanoscience equivalent of putting a square peg in a round hole. more»

Increasing NMR/MRI Sensitivity through Optical Hyperpolarization in Diamond

Dynamic nuclear polarization, which transfers the spin polarization of electrons to nuclei, is routinely applied to enhance the sensitivity of nuclear magnetic resonance. This method is particularly useful when spin hyperpolarization can be produced and controlled optically or electrically. Here the researchers show complete polarization of nuclei located near optically polarized nitrogen-vacancy centres in diamond. more»

Single-Bond-Resolved Images Catch Chemistry in Action

MSD's Felix Fischer, Michael Crommie, and collaborators have taken the first single-bond-resolved images of individual organic molecules immediately before and after they undergo a complex chemical reaction. The results provide powerful new insights into organic chemical reactions, which underlie biology and are critically important to industrial processes such as liquid fuel production. more»

Lower-Limits of the Nanostructured Approach To a Better Thermoelectric

A team of scientists, headed by Jeffrey Urban of the Molecular Foundry, have achieved ultralow thermal conductivity in polycrystalline thin films of cadmium selenide (CdSe). The results help identify fundamental limits of grain-boundary scattering as a means of improving thermoelectric efficiency. more»

Microfluidic Electrochemical Energy Conversion for Artificial Photosynthesis

Researchers at the Joint Center for Artificial Photosynthesis have developed a versatile microfluidic test-bed which can be used to optimize the integrated catalysis and mass transport components of electrochemical energy conversion devices. The small size and versatility of the design facilitates the evaluation of new materials under development without the need for scale-up. more»

Composite Organic/Inorganic Thermoelectric is More Than Sum of Its Parts

A team led by MSD's Jeffrey Urban and Rachel Segalman have discovered highly conductive polymer behavior occurring at a polymer/nanocrystal interface. The composite organic/inorganic material is a thermoelectric – a material capable of converting heat into electricity – and has a higher performance than either of its constituent materials. The results may impact not only thermoelectrics research, but also polymer/nanocrystal composites being investigated for photovoltaics, batteries, and hydrogen storage. more»

Photonic Spin Hall Effect Captured with 2-D Metamaterial

Berkeley Lab researchers obtained the strongest signal yet of the photonic spin Hall effect by engineering a unique two-dimensional metamaterial sheet of gold nanoantennas. The work demonstrates that metamaterials allow control over not only propagation of light but also of circular polarization, results that could have important consequences for information encoding and processing. more»

Atomic Collapse Observed in Graphene

Berkeley Lab scientists have experimentally observed “atomic collapse” for the first time, confirming decades-old predictions and providing important insights for future graphene devices. more»

2012

High-Current-Density Nanostructured Photocathodes

A team of MSD researchers within the Joint Center for Artificial Photosynthesis led by Joel Ager and Ali Javey has shown that nanostructured InP can be a high performance photocathode for the conversion of sunlight into hydrogen. The combination of high efficiency and stability demonstrated in this system is a significant step towards the realization of artificial photosynthesis. more»

Peering Deep into Spintronic Materials:  Dilute Magnetic Semiconductors

MSD researchers have investigated the bulk electronic structure of the prototypical dilute magnetic semiconductor gallium manganese arsenide using a new technique called HARPES, for Hard x-ray Angle-Resolved PhotoEmission Spectroscopy. Their findings help resolve a long-standing question about the material’s ferromagnetism, which they find arises from both of the two different mechanisms that have been proposed to explain it. more»

Navigating Impurities in Graphene

MSD researchers Michael Crommie, Alex Zettl and coworkers have directly imaged how electrons respond to a charged impurity placed on electrically isolated graphene. The results shed light on the origins of graphene’s extraordinary mechanical and electronic properties. more»

Squeezing Optical Cavities to the Nanoscale

Xiang Zhang and colleagues have created the world’s smallest optical cavities, the light-amplification chamber at the heart of laser technology. The researchers circumvented the usual size limitations on optical cavities by harnessing exotic properties of metamaterials, and the unprecedented size and performance of the resulting cavities open exciting possibilities in nanophotonic applications. more»

Not All Vortex States are Created Equal

A team headed by Peter Fischer and Mi-Young Im of MSD’s Center for X-Ray Optics, in collaboration with colleagues in Japan, have discovered that magnetic-vortex formation in ferromagnetic nanodisks is asymmetric, contrary to common assumption. Their results are relevant to implementing nanodisks in data storage devices as the asymmetry could lead to failure during initialization. more»

Assembling Functional Mesoporous Architectures

Molecular Foundry researchers headed by Brett Helms and Delia Milliron have unveiled a powerful new technique to form mesoporous materials with precisely controlled structure by mating specialized block copolymers with ligand-stripped nanocrystals. Their approach opens new possibilities for making mesoporous architectures from diverse compositions of materials to achieve new properties. more»

Towards Ligand-Customized Quantum Dots

A team of researchers headed by Foundry User Eric Schwegler and Tony van Buuren of Lawrence Livermore National Laboratory has shed light on a long-standing question about passivating quantum dot surfaces with organic molecules known as ligands. Pairing theoretical modeling with X-ray absorption spectroscopy, they revealed how ligands modify optical and electronic properties of quantum dots, insights highly relevant to designing nanocrystal-based solar cells. more»

Closer Look at Nanoparticle Growth Through a Graphene Window

A team co-headed by Alex Zettl and Paul Alivisatos of the Materials Sciences Division has invented an elegant technique for encapsulating liquid samples in pockets of graphene and imaging the contents with high-resolution electron microscopy. This technique makes it possible to image a broad range of solution-phase phenomena, such as nanoparticle growth and protein folding, with unprecedented resolution. more»

Revealing Nanorod Formation with Liquid-Cell TEM

Materials Science Division researcher Haimei Zheng and colleagues have imaged iron-platinum nanoparticle forming from solution, helping resolve a decades-long debate about growth dynamics. By understanding how nanoparticles grow, researchers can better tailor their properties for cheap, efficient energy-related technologies. more»

Nanotwinned Crystal Structures for Stronger Alloys

A team headed by Materials Sciences Division researcher Andrew Minor imaged the atomic-level response of magnesium crystals to mechanical strain, revealing the origin and dynamics of the crystal structure integral to mechanical properties of metal alloys. The discovery will help researchers develop new alloys with advanced mechanical properties. more»

Organizing Nanorods with a Polymer Template

Materials Sciences Division researcher Ting Xu and colleagues at the National Center for Electron Microscopy and the Advanced Light Source have discovered a route for creating complex structures of CdS nanorods by leveraging the self-assembly of large polymer molecules. This unprecedented degree of control over nanostructure assembly will enable researchers to use them more effectively in applications like solar cells and magnetic storage devices. more»

Pioneering a Nanoscale Nuclear Materials Testing Capability

Materials Science Division faculty scientist Andy Minor and colleagues have devised a nanoscale testing technique for irradiated materials that provides macroscale materials-strength properties. This technique could help accelerate the development of new materials for nuclear applications, and reduce the amount of material required for testing of facilities already in service. more»

Nanocrystal Transformers

A team led by Materials Science Division researchers Paul Alivisatos and Haimei Zheng is breaking new ground for the design of novel materials with the first direct observation of structural transformations in semiconductor nanocrystals. Studying structural transformations in ordered materials is of great interest in many applications, ranging from light harvesting to materials manufacture and energy storage, in which such transformations affect device performance. more»

Nuclear Magnetic Resonance, Now Without Magnets

Materials Sciences Division's Alex Pines and colleagues have demonstrated the first high-resolution nuclear magnetic resonance (NMR) instrument capable of chemical analysis without large, cumbersome magnets. An inexpensive version of NMR, which reveals the identity and chemical environment of molecules or atoms, could help researchers fingerprint small quantities of a chemical in a variety of settings. more»

Imaging Electron Clouds on the Surface of Graphene

Guided by the Molecular Foundry's David Prendergast, researchers at the University of Buffalo and SEMATECH have imaged electron clouds on the surface of graphene. These clouds reveal surface folds, ripples and other distortions that can impair graphene's ability to conduct electrons. more»

Shedding Light on a Mystery of Raman Signal Enhancement

Led by the Molecular Foundry's Jeff Neaton, researchers have unraveled a mystery behind surface-enhanced Raman spectroscopy---a detection method useful for analyzing artwork and anthrax alike. more»

Electronic Life on the Edge

Led by the Materials Sciences Division's Michael Crommie, researchers have seen for the first time that electrons prefer to live on the edge---of graphene nanoribbons, a slim strip of carbon atoms arranged in a 'chicken wire' lattice just one atom thick. These findings show electrons confined to narrow channels along the edges of well-ordered graphene nanoribbons. This one-dimensional channeling of electrons could be beneficial for energy harvesting applications, such as solar cells. more»

Berkeley Lab Scientists Control Light Scattering in Graphene

Led by the Materials Sciences Division's Feng Wang, researchers have made the first direct observation of quantum interference in graphene, a 'chicken wire'-like sheet of carbon just one atom thick. These findings illuminate controls for quantum pathways in light scattering devices for material characterization or biological tagging. more»

Engineering a Practical Full-Spectrum Solar Cell

Researchers led by the Materials Science Division's Wladek Walukiewicz have designed a multiband solar cell in which two distinct materials are alloyed together using a common semiconductor fabrication technique. By engineering an alloy with multiple band gaps—the energies of light that can be absorbed by a material—costly fabrication steps can be avoided. In addition, such a design also improves the power conversion efficiency of solar cells, as a larger portion of the sun's energy can be translated into electrical current. more»

Tandem Catalysis in Nanocrystal Interfaces

Materials Sciences Division researchers Peidong Yang and Gabor Somorjai have designed layered nanocrystals that allow multiple, sequential catalytic reactions to be carried out selectively and in tandem. This achievement holds intriguing possibilities for industrial catalysis and promising green energy technologies such as artificial photosynthesis. more»

Seeing the Light - Bringing Plasmonic Nanofields Into Focus

A research team led by the Molecular Foundry's Jim Schuck demonstrated an innovative imaging concept to visualize plasmonic fields from devices with nanoscale resolution. In plasmonic devices, electromagnetic waves crowd into tiny metal structures, concentrating energy into nanoscale dimensions. This savvy coupling of electronics and photonics could be harnessed for high-speed data transmission or ultrafast detector arrays. more»

Next-Generation Chemical Mapping on the Nanoscale

A team of Molecular Foundry scientists led by Alexander Weber-Bargioni has pioneered a new chemical mapping method that provides unprecedented insight into materials at the nanoscale. more»

Engineered Biomimetic Polymers as Tunable Agents for CaCO 3 Mineralization

Molecular Foundry scientists Ron Zuckermann and Jim DeYoreo have developed a suite of protein-like materials capable of enhancing or inhibiting mineralization of inorganic solids. These engineered, non-natural polymers could enable technologies applicable to industrial crystallization, including CO 2 sequestration. more»

Grain Boundary Mapping in Polycrystalline Graphene

Using advanced electron microscopes at the National Center for Electron Microscopy, researchers have reported direct mapping of grains and grain boundaries in large-area monolayer polycrystalline graphene sheets, at length scales from micrometers to single atoms. more»