energy – Lightsources.org

Electrocatalysis – Iron and Cobalt Oxyhydroxides examined

2023/02/162023/02/23

A team led by Dr. Prashanth W. Menezes (HZB/TU-Berlin) has now gained insights into the chemistry of one of the most active anode catalysts for green hydrogen production. They examined a series of Cobalt-Iron Oxyhydroxides at BESSY II and were able to determine the oxidation states of the active elements in different configurations as well as to unveil the geometrical structure of the active sites. Their results might contribute to the knowledge based design of new highly efficient and low cost catalytical active materials.

Very soon, we need to become fossil free, not only in the energy sector, but as well in industry. Hydrocarbons or other raw chemicals can be produced in principle using renewable energy and abundant molecules such as water and carbon dioxide with the help of electrocatalytically active materials. But at the moment, those catalyst materials either consist of expensive and rare materials or lack efficiency.

Key reaction in water splitting

A team led by Dr. Prashanth W. Menezes (HZB/TU-Berlin) has now gained insights into the chemistry of one of the most active catalysts for the anodic oxygen evolution reaction (OER), which is a key reaction to supply electrons for the hydrogen evolution reaction (HER) in water splitting. The hydrogen can then be processed into further chemical compounds, e.g., hydrocarbons. Additionally, in the direct electrocatalytic carbon dioxide reduction to alcohols or hydrocarbons, the OER also plays a central role.

Read more on the HZB website

Image: LiFe_x-1Co_x Borophosphates have been used as inexpensive anodes for the production of green hydrogen. Their dynamic restructuring during OER as well as their catalytically active structure, have been elucidated via X-ray absorption spectroscopy.

Credit: © P. Menezes / HZB /TU Berlin

Graphene coated nickel foams for hydrogen storage

2022/12/222023/01/12

Hybrid composites where graphene (Gr) and other 2D materials replicate the meso-and micro-structure of 3D porous substrates have shown innovative functionalities in catalysis and energy-related fields. Concerning hydrogen storage, the high surface-to-volume ratio exhibited by both 2D and 3D components of the hybrid material is expected to increase the efficiency of surface chemisorption and bulk absorption of hydrogen in comparison to the flat counterparts. To explore this possibility, we have grown single layer Gr on porous nickel foams and have investigated the interaction with H atoms as a function of the temperature by using X-ray photoelectron spectroscopy and thermal programmed desorption (TPD) at the SuperESCA beamline of Elettra.

The growth of Gr on the Ni foam was obtained by exposing the sample at 773 K to ethylene. Selected C 1s spectra taken at increasing growth time are shown in Fig.1a. Upon exposure to ethylene, the carbide phases (N₁-N₄ components) observed in the pristine sample disappear, while new Gr components (labeled C₀ and C₁) progressively increase in intensity and eventually saturate. The component C₀ is attributed to Gr_S regions grown on the (111) foam grains, where the interaction with the support is as strong as that between Gr and the ordered Ni(111) surface; C₁ is attributed to Gr_W regions that are rotated with respect to (111) grains, or are grown on Ni grains exposing different orientations, and therefore, are interacting weakly with the support.

Read more on the Elettra website

Figure 1: a) C 1s spectra measured during the Gr growth after 0, 3,10,16 and 44 minutes of exposure to ethylene at 773 K and (bottom) at RT after growth; b) C 1s spectra acquired on the Gr/foam hydrogenated with the same H dose at the indicated temperatures T_H and c) TPD curves measured during sample annealing.

Fig. 1b shows the C 1s spectra measured on the Gr/foam exposed to a flux of H atoms at temperatures T_H between 78 and 298 K. Starting from T_H=98 K, the C 1s line shapes appear broadened on the high binding energy (BE) side, due to the appearance of a component (labeled A) at 285.0 eV, and also on the low BE side, due to another component (labeled B) at 284.1 eV. A and B are ascribed to C atoms directly bonded to H atoms and to their first neighbors, and therefore indicate the occurrence of H chemisorption on Gr. From 198 K, some intensity is transferred from C₀ to C₁, because at this temperature the H atoms start to intercalate below Gr_S, which detaches gradually from the substrate. The intercalation under the nearly free-standing Gr_W remains undetected, because here the penetration of H underneath does not cause any measurable extra-shift of the C₁ component.

Fig. 1c shows H₂ TPD curves measured while heating the Gr/foam hydrogenated at increasing T_H. The desorption of H atoms chemisorbed on Gr originates solely the weak peak G at ~ 650 K. Hence, all other TPD features correspond to the desorption of H atoms intercalated below Gr and residing at the Ni foam surface or even diffused into the Ni bulk. Hence, differently from Gr_S, where H atoms intercalate only for T_H ~ 198 K, intercalation below Gr_W occurs at much lower temperatures. The TPD curves up to T_H=173 K are dominated by the D peak, due to the desorption of H atoms penetrated in metastable subsurface sites of the Ni foam. The H₂ release at higher temperatures is related to the slower desorption of bulk H atoms and to the release of H atoms chemisorbed on the Ni surface. It turns out that the highest quantity of loaded hydrogen is detected for T_H= 113 K and amounts to ~ 5 times the quantity which saturates the Ni (111) surface with equivalent macroscopic lateral dimension.

Innovative fuels for Small Modular Reactors

2022/12/012022/12/06

If Canada is to meet its target of net-zero emissions by 2050, our country must transition to a diverse, innovative range of alternative sources of energy.

Mouna Saoudi, a materials scientist at Canadian Nuclear Laboratories (CNL), is using the Canadian Light Source at the University of Saskatchewan to explore how advanced nuclear fuels for small modular reactors (SMRs) could be used to help fill the gap between fossil fuels and renewables.

“SMRs would be an efficient way to reach net zero by 2050, which is an ambitious but hopefully achievable goal,” says Saoudi.

SMRs can power electrical grids, provide process heat, and offer energy solutions for various industries — such as remote mining operations.

Saoudi is currently investigating how types of advanced nuclear fuels behave under different reactor conditions.

“My main focus is characterization of advanced nuclear fuels for potential use in small modular reactors,” Saoudi says.

The advanced fuels combine uranium oxide — the main element used in nuclear fuel for decades —with the naturally occurring and abundant element thorium in oxide form. Saoudi says that there are many advantages to mixing the two elements, including increased efficiency and better in-reactor performance.

Using the HXMA beamline, Saoudi was able to confirm the similar distribution of the two elements, uranium and thorium, in the mixed fuel oxides. Saoudi believes this was the first time the CLS has been used for this type of study.

Saoudi has been working with USask researcher Andrew Grosvenor from the Department of Chemistry. Their findings were recently published in the Journal of Nuclear Materials.

The CLS allowed Saoudi and her collaborators to investigate the electronic and local structure of the fuel — crucial information needed to identify the optimum fuel composition that would have better in-reactor performance than that of uranium oxide.

Read more on the CLS website

Image: (Left to right) Dr. Than Do, Dr. Mouna Saoudi, and Dr. Julien Lang, R&D scientists at Canadian Nuclear Laboratories (CNL).

Atomic displacements in High-Entropy Alloys examined

2022/06/272022/06/28

High-entropy alloys of 3d metals have intriguing properties that are interesting for applications in the energy sector. An international team at BESSY II has now investigated the local order on an atomic scale in a so-called high-entropy Cantor alloy of chromium, manganese, iron, cobalt and nickel. The results from combined spectroscopic studies and statistical simulations expand the understanding of this group of materials.

High-entropy alloys are under discussion for very different applications: Some materials from this group are suitable for hydrogen storage, others for noble metal-free electrocatalysis, radiation shielding or as supercapacitors.

The microscopic structure of high-entropy alloys is very diverse and changeable; in particular, the local ordering and the presence of different secondary phases affect significantly the macroscopic properties such as hardness, corrosion resistance and also magnetism. The so-called Cantor alloy, which consists of the elements chromium, manganese, iron, cobalt and nickel mixed in an equimolar proportion, can be considered as a suitable model system for the whole class of these materials.

Local structure studied at BESSY II

Scientists from the Federal Institute for Materials Research (BAM, Berlin), the University of Latvia in Riga, Latvia, the Ruhr University in Bochum and the HZB have now studied the local structure of this model system in detail. Using X-ray absorption spectroscopy (EXAFS) at BESSY II, they were able to precisely track each individual element and their displacements from the ideal lattice positions for this system in the most unbiased manner with the help of statistical calculations and the reverse Monte Carlo method.

The fourth signature of the superconducting transition in cuprates

2022/01/262022/02/03

The results cap 15 years of detective work aimed at understanding how these materials transition into a superconducting state where they can conduct electricity with no loss.

When an exciting and unconventional new class of superconducting materials was discovered 35 years ago, researchers cheered.

Like other superconductors, these materials, known as copper oxides or cuprates, conducted electricity with no resistance or loss when chilled below a certain point – but at much higher temperatures than scientists had thought possible. This raised hopes of getting them to work at close to room temperature for perfectly efficient power lines and other uses.

Research quickly confirmed that they showed two more classic traits of the transition to a superconducting state: As superconductivity developed, the material expelled magnetic fields, so that a magnet placed on a chunk of the material would levitate above the surface. And its heat capacity – the amount of heat needed to raise their temperature by a given amount – showed a distinctive anomaly at the transition.

But despite decades of effort with a variety of experimental tools, the fourth signature, which can be seen only on a microscopic scale, remained elusive: the way electrons pair up and condense into a sort of electron soup as the material transitions from its normal state to a superconducting state.

Now a research team at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University has finally revealed that fourth signature with precise, high-resolution measurements made with angle-resolved photoemission spectroscopy, or ARPES, which uses light to eject electrons from the material. Measuring the energy and momentum of those ejected electrons reveals how the electrons inside the material behave.

In a paper published in Nature, the team confirmed that the cuprate material they studied, known as Bi2212, made the transition to a superconducting state in two distinct steps and at very different temperatures.

Read more on the SLAC website

Image: How can you tell if a material is a superconductor? Four classic signatures are illustrated here. Left to right: 1) It conducts electricity with no resistance when chilled below a certain temperature. 2) It expels magnetic fields, so a magnet placed on top of it will levitate. 3) Its heat capacity – the amount of heat needed to raise its temperature by a given amount – shows a distinctive anomaly as the material transitions to a superconducting state. 4) And at that same transition point, its electrons pair up and condense into a sort of electron soup that allows current to flow freely. Now experiments at SLAC and Stanford have captured this fourth signature in cuprates, which become superconducting at relatively high temperatures, and shown that it occurs in two distinct steps and at very different temperatures. Knowing how that happens in fine detail suggests a new and very practical direction for research into these enigmatic materials.

Credit: Greg Stewart, SLAC National Accelerator Laboratory

Cyborg plants: roots can store energy

2022/01/192022/01/20

Researchers of the HyPhOE European Project have developed biohybrid plants with an electronic root system, which could be used to store energy or as electronic sensors. This study proved the integration of circuits and electrochemical devices into the plants without damaging them, so that they continued to grow and adapt to their new hybrid state. Experiments at the NCD-SWEET beamline of the ALBA Synchrotron were crucial to shed light on the plant-based technology field.

Plants are amazing machines: not only they are solar-powered and convert carbon dioxide into chemical energy, but they are also capable of producing cellulose, the most abundant biopolymer on Earth, and can self-repair via tissue regeneration. All these factors make plants the perfect candidates for developing biohybrid technological systems, integrating smart materials and devices into their structure.

In a recent publication, the team led by researcher Eleni Stavrinidou from the Linköping University (Sweden) has presented a study about biohybrid plants with an electronic root system. They found out how to integrate circuits and electrochemical devices into the plants without damaging them, so that they can continue to grow and develop, and use them as supercapacitors or electronic sensors.

The results pave the way for using roots for energy storage and the creation of a root-based supercapacitor. Supercapacitors based on conductive polymers and cellulose offer an environmentally friendly alternative for energy storage that may also be more affordable than those currently in use. As a proof of concept, the research team built a supercapacitor where the roots served as the charge storage electrodes.

Another possible application of these plant-based systems are electronic sensors. For example, by adding a humidity sensor in the root, the information could be transmitted through the electronic root network to an intelligent system, which could act accordingly by increasing or decreasing the frequency of irrigation. These discoveries open the door to new intelligent stimulus-response applications.

This study is part of the European project Hybrid Electronics Based on Photosynthetic Organisms (HyPhOE), which involves several European institutions and aims to achieve a symbiosis between photosynthetic organisms and technology.

Read more on the ALBA website

Image: Bean plant before, during and after functionalization

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

2020/06/102020/07/02

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 Cu_xO_y 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

2020/06/092020/06/10

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

2020/05/042020/07/02

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

2020/01/082020/01/16

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.

The most complete study of battery failure sees the light

2019/05/282019/06/05

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

$New lens system for brighter, sharper diffraction images$

New lens system for brighter, sharper diffraction images

2019/04/252019/05/20

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.

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

2019/03/272019/04/08

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.

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

2019/02/212019/03/13

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.

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

2019/02/112019/02/14

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

2018/12/112018/12/12

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.