Formation of a 2D meta-stable oxide in reactive environments

The chemical behaviour of solid material surfaces is an important physical characteristic for applications of catalysis, chemical sensors, fuel cells and electrodes. A research team from the Max Planck Institute for Chemical Energy Conversion has now described an important phenomenon that can occur when metal alloys are exposed to reactive environments at the synchrotron source BESSY II.

In a recent work published in ACS Applied Materials & Interfaces, a researchers’ team led by Dr. Mark Greiner (Surface Structure Analysis, Department of Heterogeneous Reactions) demonstrates an important phenomenon that can occur when metal alloys face reactive environments. They can form meta-stable 2D oxides on their surfaces. Such oxides exhibit chemical and electronic properties that are different from their bulk counterparts. Due to their meta-stability, their existence is also difficult to predict.

Read more on the BESSY II (at HZB) website

Image : Illustration of a CuxOy structure formed on a AgCu alloy in oxidizing environments described in this work. (c) ACS Applied Materials & Interfaces.

Credit: © (2020) ACS Publishing

Atomic vibrations play key role in material phase change

A research group working with MAX IV’s FemtoMAX beamline has succeeded to slow the phase change from the solid to liquid state in the semiconductor, indium antimonide (InSb), by reducing the inherent vibrations between atoms. An important precursory step in the process was non-thermal melting of the sample, which broke its atomic bonds. This revealed that unbound atoms move with the velocity they had at the instant the bonds were broken. Further it showed that initial velocity is governed by atomic vibrations, which in turn are temperature dependent. The findings are steps toward functional manipulation of material structure during phase transitions.

Imagine a world where we control the structure of materials by subjecting them to short-pulse laser radiation. This is the implication of research that allows us to alter the timing when phase change occurs.

Melting a material with or without heat produces a similar result, at a similar speed. What is going on at the atomic level is quite different, however. Thermal heating excites electrons to a higher energy state. Electron-phonon coupling then equilibrates the electron and lattice temperature which makes the lattice vibrate so violently that atomic bonds break. Non-thermal heating also excites electrons but breaks the bonds instantly—within femtoseconds—and releases atoms from their original structural configuration. Scientists seek to distinguish what happens after bonds sever due to these excited electrons.

Read more on the MAX IV website

Image : FemtoMAX beamline at MAX IV

How new materials increase the efficiency of direct ethanol fuel cells

A group from Brazil and an HZB team have investigated a novel composite membrane for ethanol fuel cells. It consists of the polymer Nafion, in which nanoparticles of a titanium compound are embedded by the rarely explored melt extrusion process. At BESSY II they were able to observe in detail, how the nanoparticles in the Nafion matrix are distributed and how they contribute to increase proton conductivity.

Ethanol has five times higher volumetric energy density (6.7 kWh/L) than hydrogen (1.3 kWh/L) and can be used safely in fuel cells for power generation. In Brazil in particular there is great interest in better fuel cells for ethanol as all the country distributes low-cost ethanol produced in a renewable way from sugar cane. Theoretically, the efficiency of an ethanol fuel cell should be 96 percent, but in practice at the highest power density it is only 30 percent, due to a variety of reasons. So there is great room for improvements.

Nafion with nanoparticles

A team led by Dr. Bruno Matos from the Brazilian research institute IPEN is therefore investigating novel composite membranes for direct ethanol fuel cells. A promising solution is tailoring new polymer-based composite electrolyte materials to replace the state-of-the-art polymer electrolyte such as Nafion. Matos and his team use melt extrusion process to produce composite membranes based on Nafion with additional titanate nanoparticles, which have been functionalized with sulfonic acid groups.

Read more on BESSY II (at HZB) website

Image: The material consists of Nafion with embedded nanoparticles.

Credit: © B.Matos/IPEN

Sizing up red phosphorus for use in future battery technologies

A step forward in the search for better anodes for sodium-ion batteries

In 2015, the world used around 16 TW of energy, and this is predicted to rise to about 24 TW by 2035. The need for high-performing energy storage is growing, with the increased use of both intermittent, renewable power sources and electric vehicles. The current technology of choice is lithium-ion batteries (LIBs), which have high specific energies, rate capabilities, and cycle lives. However, LIBs rely on lithium and cobalt, two elements with an uneven geographical distribution. Disruptions to supply can cause price spikes, and there are concerns that the world’s total cobalt reserves may not meet future demand. Scientists are therefore investigating the potential of other battery technologies, which use cheap and widely available materials, such as sodium-ion batteries (SIBs). Although operation and manufacturing processes for SIBs are similar to those for LIBs, they cannot use the graphite anodes that are common in LIS. In research recently published in Energy Fuels, a team of researchers from the University of Oxford investigated how the particle-size distribution of red phosphorus affects the performance of composite anodes for SIBs.

Image: a) TEM image of the composite material made by mixing phosphorus (Dv90 = 0.79 μm) with graphite for 48 h in which graphene planes can be seen on the surface of the phosphorus particle. (b) Plotting the ratio between the integrated areas of the peaks fitted on the photoelectron spectra collected from the composite versus the probing depth shows that surficial P–C chemical bonds gradually decrease and P–P bonds increase as we move deeper toward the particle bulk. The areas are calculated from the fit shown in panels c–e, with the photoelectron spectra of the P 2p region acquired using increasing incident radiation energy.

>Read more on the Diamond Light Source website

The most complete study of battery failure sees the light

An international team of researchers just published in Advanced Energy Materials the widest study on what happens during battery failure, focusing on the different parts of a battery at the same time. The role of the ESRF was crucial for its success.

We have all experienced it: you have charged your mobile phone and after a short period using it, the battery goes down unusually quickly. Consumer electronics seem to lose power at uneven rates and this is due to the heterogeneity in batteries. When the phone is charging, the top layer charges first and the bottom layer charges later. The mobile phone may indicate it’s complete when the top surface level is finished charging, but the bottom will be undercharged. If you use the bottom layer as your fingerprint, the top layer will be overcharged and will have safety problems.
The truth is, batteries are composed of many different parts that behave differently. Solid polymer helps hold particles together, carbon additives provide electrical connection, and then there are the active battery particles storing and releasing the energy.
An international team of scientists from ESRF, SLAC, Virginia Tech and Purdue University wanted to understand and quantitatively define what leads to the failure of lithium-ion batteries. Until then, studies had either zoomed in on individual areas or particles in the cathode during failure or zoomed out to look at cell level behavior without offering sufficient microscopic details. Now this study provides the first global view with unprecedented amount of microscopic structural details to complement the existing studies in the battery literature.

>Read more on the ESRF website

New lens system for brighter, sharper diffraction images

Researchers from Brookhaven Lab designed, implemented, and applied a new and improved focusing system for electron diffraction measurements.

To design and improve energy storage materials, smart devices, and many more technologies, researchers need to understand their hidden structure and chemistry. Advanced research techniques, such as ultra-fast electron diffraction imaging can reveal that information. Now, a group of researchers from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have developed a new and improved version of electron diffraction at Brookhaven’s Accelerator Test Facility (ATF)—a DOE Office of Science User Facility that offers advanced and unique experimental instrumentation for studying particle acceleration to researchers from all around the world. The researchers published their findings in Scientific Reports, an open-access journal by Nature Research.
Advancing a research technique such as ultra-fast electron diffraction will help future generations of materials scientists to investigate materials and chemical reactions with new precision. Many interesting changes in materials happen extremely quickly and in small spaces, so improved research techniques are necessary to study them for future applications. This new and improved version of electron diffraction offers a stepping stone for improving various electron beam-related research techniques and existing instrumentation.

>Read more on the NSLS-II at Brookhaven Lab website

Image: Mikhail Fedurin, Timur Shaftan, Victor Smalyuk, Xi Yang, Junjie Li, Lewis Doom, Lihua Yu, and Yimei Zhu are the Brookhaven team of scientists that realized and demonstrated the new lens system for as ultra-fast electron diffraction imaging.

Funding research crucial to Africa: Energy and healthcare

The 27th March 2019 saw the official launch of START (Synchrotron Techniques for African Research and Technology), a £3.7M grant awarded to a consortium of researchers led by Diamond Light Source by the Science and Technology Facilities Council (STFC) to work with African scientists on START.

Africa does not yet have a synchrotron light source, but African researchers are keen to apply synchrotron techniques to their research problems. The START project will fund research posts in Africa and the UK with a focus on two key areas crucial to development in Africa – energy and healthcare . The scientific results that come out of the project will be valuable in themselves, and may also lead to commercial applications, but START will also promote the development of research capabilities within Africa, and international research collaborations.

For Diamond Principal Investigator, Prof. Chris Nicklin, this will be the most important result: It is an exciting prospect to work together on these challenging problems and this funding will enable us to form very strong links at all levels, in particular helping to train the next generation of researchers in nations that have not had the chance to access and exploit synchrotron based techniques in their research. The work will focus around the development needs of African countries, driven by the Africa-based investigators and the non-government organisations (NGOs) that we have on board.

>Read more on the Diamond Light Source website

Watching molecules in a light-triggered catalyst ring ‘like an ensemble of bells’

A better understanding of these systems will aid in developing next-generation energy technologies.

Photocatalysts ­– materials that trigger chemical reactions when hit by light – are important in a number of natural and industrial processes, from producing hydrogen for fuel to enabling photosynthesis.
Now an international team has used an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory to get an incredibly detailed look at what happens to the structure of a model photocatalyst when it absorbs light.
The researchers used extremely fast laser pulses to watch the structure change and see the molecules vibrating, ringing “like an ensemble of bells,” says lead author Kristoffer Haldrup, a senior scientist at Technical University of Denmark (DTU). This study paves the way for deeper investigation into these processes, which could help in the design of better catalysts for splitting water into hydrogen and oxygen for next-generation energy technologies.
“If we can understand such processes, then we can apply that understanding to developing molecular systems that do tricks like that with very high efficiency,” Haldrup says.

>Read more on the Linac Coherent Light Source at SLAC website

Image: When photocatalyst molecules absorb light, they start vibrating in a coordinated way, like an ensemble of bells. Capturing this response is a critical step towards understanding how to design molecules for the efficient transformation of light energy to high-value chemicals.
Credit: Gregory Stewart/SLAC National Accelerator Laboratory

2 for the price of 1: how double ionization becomes an efficient process

Double ionization is a unique mechanism where two electrons are simultaneously emitted from an atom or molecule. Typically, it’s a very weak process occurring only a few percent of the time compared to single ionization where only one electron is emitted. This is due to double ionization requiring the correlated action of two electrons hit by an energetic photon or particle. However, in a recent experiment, is has been shown that double ionization doesn’t necessarily need to be a minor effect and can even be the primary ionization mechanism.
The enhancement is likely due to double ionization proceeding through a new type of energy transfer process termed double intermolecular Coulombic decay, or dICD, for short. To experimentally observe this mechanism, dimers consisting of two alkali metal atoms were attached to the surface of helium nanodroplets. The dICD process, schematically shown in Fig. 1, occurs through an electronically excited helium atom (red), produced by synchrotron radiation, interacting with the neighboring alkali dimer (blue and white) resulting in energy transfer and double ionization. To distinguish dICD from other processes, the kinetic energies of the emitted electrons were measured in coincidence with their alkali ion counterparts.

>Read more on the Elettra website

Image: schematic view of double Intermolecular Coulombic decay (dICd).

Progress on low energy electronics

Soft X-ray experiments used to characterise new thin film topological Dirac Semimetal

A large international collaboration including scientists from Monash University, the ARC Centre for Future Low Energy Electronics (FLEET), the Monash Centre for Anatomically Thin Materials and the Australian Synchrotron reported today in Nature on the development of an advanced material that is able to switch between an electrically conductive state to an insulating state, simply by applying an electric field.
The work represents a step towards the development of a new generation of ultra-low energy electronics at room temperature. 
Co-author Dr Anton Tadich, a beamline scientist at the Soft X-ray beamline and Partner Investigator with FLEET, collaborated with investigators from Monash University, Singapore and Lawrence Berkeley National Lab on the use of photoemission techniques at the Australian Synchrotron X-ray Photoelectron Spectroscopy (XPS) and the Advanced Light Source in the US Angle Resolved Photoelectron Spectroscopy, (ARPES).
The chemical composition and growth mechanisms of thin films of the topological Dirac semi-metal sodium bismuthide Na3Bi on a silicon substrate was investigated using XPS at the Australian Synchrotron’s Soft X-ray beamline.

>Read more on the Australian Synchrotron at ANSTO website

Improving lithium-ion battery capacity

Toward cost-effective solutions for next-generation consumer electronics, electric vehicles and power grids.

The search for a better lithium-ion battery—one that could keep a cell phone working for days, increase the range of electric cars and maximize energy storage on a grid—is an ongoing quest, but a recent study done by Canadian Light Source (CLS) scientists with the National Research Council of Canada (NRC) showed that the answer can be found in chemistry.
“People have tried everything at an engineering level to improve batteries,” said Dr. Yaser Abu-Lebdeh, a senior research officer at the NRC, “but to improve their capacity, you have to play with the chemistry of the materials.”

>Read more on the Canadian Light Source website

Image: The decomposition of a polyvinylidene fluoride (PVDF) binder in a high energy battery.
Credit: Jigang Zhou

Light-activated, single- ion catalyst breaks down carbon dioxide

X-ray studies reveal structural details that may point the way to designing better catalysts for converting pollutant gas into useful products

A team of scientists has discovered a single-site, visible-light-activated catalyst that converts carbon dioxide (CO2) into “building block” molecules that could be used for creating useful chemicals. The discovery opens the possibility of using sunlight to turn a greenhouse gas into hydrocarbon fuels.

The scientists used the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science user facility at Brookhaven National Laboratory, to uncover details of the efficient reaction, which used a single ion of cobalt to help lower the energy barrier for breaking down CO2. The team describes this single-site catalyst in a paper just published in the Journal of the American Chemical Society.

Converting CO2 into simpler parts—carbon monoxide (CO) and oxygen—has valuable real-world applications. “By breaking CO2, we can kill two birds with one stone—remove CO2 from the atmosphere and make building blocks for making fuel,” said Anatoly Frenkel, a chemist with a joint appointment at Brookhaven Lab and Stony Brook University. Frenkel led the effort to understand the activity of the catalyst, which was made by Gonghu Li, a physical chemist at the University of New Hampshire.

>Read more on the NSLS-II at Brookhaven National Laboratory website

Image: National Synchrotron Light Source II (NSLS-II) QAS beamline scientist Steven Ehrlich, Stony Brook University (SBU) graduate student Jiahao Huang, and Brookhaven Lab-SBU joint appointee Anatoly Frenkel at the QAS beamline at NSLS-II.

Empowering multicomponent cathode materials for sodium ion batteries

…by exploring three-dimensional compositional heterogeneities

Energy storage devices have revolutionized the modern electronics industry by enabling the widespread application of portable electronic devices. Moreover, these storage devices also have the potential to reduce the dependence on fossil fuels by implementing electric vehicles in the market. To date, lithium ion batteries have dominated the market because of the high energy density delivered by them. However, one should look into the sustenance of such devices because Li is not one of the most abundant metals on Earth’s crust. Thus, developing an alternative to lithium ion batteries has become one of the key issues to ensure the sustainable future of energy storage devices. Sodium ion batteries provide one such alternative. Out of all the components of a battery, cathode materials play one of the key roles in determining the overall performance of such batteries. Unfortunately, sodium-ion batteries have been lagging behind their lithium ion counterpart in terms of performance. Thus, new design strategies must be undertaken in order to improve the performance of cathode materials for sodium ion batteries.

>Read more on the SSRL at SLAC website

Image (extract): Three-dimensional elemental associations of pristine Na0.9Cu0.2Fe0.28Mn0.52O2 studied through transmission x-ray tomography. a) Visualizing the surface elemental associations at different angles with different colors corresponding to different association, and b) 2D cross-sectional association maps showing the bulk elemental associations. [Energy Environ. Sci., DOI: 10.1039/C8EE00309B (2018)] See entire figure here.

Understanding reaction pathways leading to MnO2 polymorph formation

Computational driven design of materials has provided guidelines for designing novel materials with desired properties, especially for metastable materials, which may have superior functionalities than its stable counterparts [1]. However, the synthesis of these metastable materials is usually challenging. The current computational approaches are not able to predict reaction pathways passing through intermediate or metastable phases. As a consequence, the synthesis of many compounds still remains Edisonian, meaning that repeated iteration is usually required to find the reaction conditions needed for synthesizing targeted materials with desired properties. To reduce the amount of cost and effort during this discovery process, a predictive theory for directing the synthesis of materials is necessary.

In the recent article “Understanding Crystallization Pathways Leading to Manganese Oxide Polymorph Formation [2]”, researchers from SLAC, LBNL, MIT, Colorado School of Mines, and NREL combined theory and experimental approaches to develop and demonstrate a theoretical framework that guides the synthesis of intermediate/metastable phases. This ab initio-computation based framework calculates the influence of particle size and solution composition on the stability of polymorph (substances having the same composition but different crystallographic structures), and predicts the phases that will appear along the different reaction pathways.

>Read more on the SSRL at SLAC website

Image (extract): (a) Size-dependent phase diagram of MnO2 polymorphs. The three arrows mark the reaction progression from nano-size to bulk at different potassium concentrations. (b-d) The evolution of x-ray scattering pattern with time along [K+] = 0 M (b), 0.2 M (c), and 0.33M (d). The identities and the fractions of the phases are marked in the subfigure to the right. (e-f) Electron beam diffraction patterns of the δ” phase and δ’ phase harvested from [K+] = 0 M and 0.2 M, respectively. See all figures here.

X-Ray Experiment confirms theoretical model for making new materials

By observing changes in materials as they’re being synthesized, scientists hope to learn how they form and come up with recipes for making the materials they need for next-gen energy technologies.

Over the last decade, scientists have used supercomputers and advanced simulation software to predict hundreds of new materials with exciting properties for next-generation energy technologies.

Now they need to figure out how to make them.

To predict the best recipe for making a material, they first need a better understanding of how it forms, including all the intermediate phases it goes through along the way – some of which may be useful in their own right.

Now experiments at the Department of Energy’s SLAC National Accelerator Laboratory have confirmed the predictive power of a new computational approach to materials synthesis. Researchers say that this approach, developed at the DOE’s Lawrence Berkeley National Laboratory, could streamline the creation of novel materials for solar cells, batteries and other sustainable technologies.

>Read more on the Stanford Synchrotron Radiation Lightsource at SLAC website

Image: In an experiment at SLAC, scientists loaded ingredients for making a material into a thin glass tube and used X-rays (top left) to observe the phases it went through as it was forming (shown in bubbles). The experiment verified theoretical predictions made by scientists at Berkeley Lab with the help of supercomputers (right).
Credit: Greg Stewart/SLAC National Accelerator Laboratory

Brookhaven Lab scientist receives Early Career Research Program Funding

Valentina Bisogni, an associate physicist at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, has been selected by DOE’s Office of Science to receive significant research funding as part of DOE’s Early Career Research Program.

The effort, now in its ninth year, is designed to bolster the nation’s scientific workforce by providing support to exceptional researchers during the crucial early career years, when many scientists do their most formative work. Bisogni is among a total of 84 recipients selected this year after a competitive review of proposals. Thirty winners come from DOE national laboratories and 54 from U.S. universities.

“Supporting talented researchers early in their career is key to building and maintaining a skilled and effective scientific workforce for the nation. By investing in the next generation of scientific researchers, we are supporting lifelong discovery science to fuel the nation’s innovation system,” said Secretary of Energy Rick Perry. “We are proud of the accomplishments these young scientists have already made, and look forward to following their achievements in years to come.”

Each researcher will receive a grant of up to $2.5 million over five years to cover their salary and research expenses. A list of the 84 awardees, their institutions, and titles of their research projects is available on DOE’s Early Career Research Program webpage.

>Read more on the NSLS-II at Brookhaven Lab website

Image: Valentina Bisogni is shown preparing samples at NSLS-II’s Soft Inelastic X-ray Scattering beamline, where she will conduct her research funded through DOE’s Early Career Research Program.