Diamond Light Source – Page 2

Fred Mosselmans’ #My1stLight

2022/12/082022/12/08

This is the first EXAFS dataset I recorded for my PhD in December 1987 at station 9.2 of the SRS. It is of a molybdenum foil. I had been to the SRS after its HBL upgrade to help out on other peoples beamtimes but this is the first dataset that was part of my project. I went on to work at Daresbury and then Diamond, but when I recorded it using a monochrome Textronix terminal, I had no idea I would spend my working life collecting thousands of EXAFS and related spectra. The data was saved to a 3.5 “ floppy disk. The file takes up 35 kB and has a date stamp of “791022”, which I don’t understand, was started at 4 minutes to 7 in the morning with the ring current at 70mA.

Fred Mosselmans is Principal Beamline Scientist for Diamond’s I20 beamline LOLA: Versatile X-ray Spectroscopy

Mirian Garcia-Fernandez’s #My1stLight

2022/12/072022/12/08

Diamond’s I21 Resonant Inelastic X-ray Scattering (RIXS) beamline achieved first light in 2016. Mirian’s #My1st Light contribution shows the I21 team in the Diamond Control Room observing this fantastic achievement.

I21 is a dedicated Resonant Inelastic soft X-ray Scattering (RIXS) beamline that provides a highly monochromatised, focused and tunable X-ray beam onto materials, while detecting and energy-analysing scattered X-rays using a spatially-resolved two-dimensional detector. By studying the energy and momentum differences between the incident and the outgoing X-rays, one can obtain information such as the local lattice structure (local crystal field), electron orbitals (orbital excitations), collective lattice vibration (phonons), magnetic (spinons/magnons) and charge excitations of the material under investigation.

Success from widening access to basic science research tools and synchrotron expertise in Africa

2022/11/102022/11/11

A focus of UNESCO’s International Year of Basic Sciences for Sustainable Development is ‘enhancing inclusive participation in science’. Diamond Light Source was a key partner in START, a collaborative project that sought to foster the development of Synchrotron Techniques for African Research and Technology (START), which ran from 2018 to 2021 with a £3.7 M grant from the Global Challenges Research Fund (GCRF) provided by the UK’s Science and Technology Facilities Council (STFC). Today on World Science Day for Peace and Development, we are highlighting health and energy research enabled by START.

Diamond played a pivotal role in the project, providing African scientists with crucial access to world class synchrotron techniques, beamtime, training and mentoring. Research focused on structural biology and energy materials to address key United Nations’ Sustainable Development Goals for health (SDG 3), energy (SDG 7), climate (SDG 13), and life-long learning (SDG 4).

Addressing worldwide energy challenges

Catalysis is essential for the development of a sustainable world and was a focus of the energy materials arm of the grant, along with solar energy, which is a well-recognised sustainable energy solution. These are just two areas in the physical sciences that were investigated as part of START.

Working towards better renewable energy solutions

Catalysis has many applications in renewable energy, where waste biomass is converted to liquid biofuels, or waste CO₂ is converted to high value chemicals that can be used in our daily life, or as an alternative to fossil fuels. These applications rely on catalysts but to make this process more sustainable and efficient, advanced techniques are required to understand how the catalysts work under operating conditions. A group of START collaborators used Diamond to understand more about catalyst materials. They were investigating furfural, a bio-derived molecule that can be converted to many useful products that can be used for renewable energy. However, bio-derived compounds are highly functionalised – many parts of the molecular structure can undergo chemical change. Palladium (Pd) nanoparticles are widely used as an active component in furfural hydrogenation – a specific type of reaction that involves the addition of hydrogen to a compound – however, selectivity to specific products is a big challenge. Using X-ray absorption spectroscopy at Diamond, the team demonstrated that a Pd/NiO catalyst can hydrogenate furfural using a dual site process. This work has significant implications for the upgrading of bioderived feedstocks, suggesting alternative ways for promoting selective transformations and reducing the reliance on precious metals.

Image: START logo

Diamond’s socio-economic impact of over £2.6 billion on UK science and economy revealed

2022/10/192022/10/26

The importance of Science to world economies highlighted at ICRI

Presenting at the prestigious International Conference on Research Infrastructures (ICRI) in Brno, Czech Republic on 19^th October, Diamond outlined a cumulative monetised impact to date on UK science and economy of £ 2.6 billion rooted in the delivery of almost 12,000 published journal papers on findings from research carried out at the UK’s synchrotron light source.Breakdown of monetised impact areas as part of the socio-economic report

The new figures released today are straightforward updates to the 2021 study by Technopolis using published methodologies where they measured and demonstrated Diamond’s scientific, technological, societal, and economic benefits. The report summarised the findings and the updated figures – including the £2.6 billion cumulative monetised impact which compares very favourably with the £1.4 billion investment made in the facility to date – and underlines the significant impact Diamond continues to achieve and the fact that the facility still costs less than a cup of coffee per year – as each UK taxpayer contributes only £2.45 a year towards its world-changing science.

Minister for Science and Investment Security Nusrat Ghani said;

Image: Breakdown of monetised impact areas as part of the socio-economic report

Access denied: Stopping rabies virus from entering cells

2022/09/282022/09/29

Structural insights pave the way for development of new vaccines and therapies against rabies

Rabies virus can cause fatal neurological disease when access to medication is scarce. Tackling this issue will require novel vaccines and therapies to be developed and the viral surface protein may be a suitable target for these interventions. This protein arranges in triplets, but the structure of this arrangement has not yet been determined and the interaction between this triplet and therapeutic agents remains to be characterised. In a recent publication in Cell Host & Microbe, a research team at the University of Oxford collaborated with the electron Bio-Imaging Centre (eBIC) at Diamond Light Source to solve the cryo-electron microscopy (cryo-EM) structure of the triplet in complex with two therapeutic agents. Building on this work, the scientists investigated the mechanism by which licensed therapies inhibit the viral protein. The structural insight gained from this work will allow for strategic development of new vaccines and therapies against the virus.

A growing medical concern with limited treatments

Rabid animals typically spread rabies virus to humans by biting and this can cause a lethal neurological infection. Despite the development of vaccines and therapeutics, over 60,000 people die each year from rabies. Most of these deaths occur in African and Southeast Asian countries, where the virus is endemic in animals and access to medical intervention is insufficient. There is a growing necessity to design accessible therapeutics in response. Currently, vaccines can prevent rabies, but multiple doses are often required to achieve protection. Exposed individuals can additionally be treated with antibodies — components of the immune system that detect and block specific microorganisms (e.g. bacteria or viruses). There is concern however that currently available antibodies may not be protective against new variants of the virus and additional antibodies need to be produced.

A dynamic viral protein drives virus entry into the cell

Vaccines and antibody therapies target a single protein on the surface of the rabies virus. This aptly named ‘fusion’ protein engages with cellular proteins and triggers fusion of the virus with the cell, allowing infection to begin. Fusion proteins come together in triplets and change shape to drive fusion. The triplets initially form an open tripod (i.e. in which the three ‘legs’ are splayed). To allow fusion, the legs then fold into a closed-tripod arrangement. The researchers purified the fusion protein as a triplet in the open-tripod arrangement to study its architecture and association with antibodies.

Image: Graphical abstract from DOI: 10.1016/j.chom.2022.07.014

Credit: reused under the CC BY 2.0 license

European Young Chemists’ Award for Sebastian Weber

2022/09/262022/09/29

In recognition of Sebastian’s PhD thesis on hard X-ray microscopy, tomography, and application of synchrotron radiation in catalysis research

Sebastian Weber, a recent PhD graduate at the Institute for Chemical Technology and Polymer Chemistry (ITCP) / Institute for Catalysis Research and Technology (IKFT) at Karlsruhe Institute of Technology (KIT), was awarded the Gold Medal in the PhD category of the European Young Chemists‘ Award. The award is presented every two years during the EuChemS Chemistry Congress on behalf of the Società Chimica Italiana (SCI) and the European Chemical Society (EuChemS). The prize highlights excellent research from young / early stage researchers across all fields of chemistry and chemical sciences. During his PhD phase, Sebastian Weber studied materials used in heterogeneous catalysis with a broad range of spatially-resolved X-ray characterisation methods, in order to gain a deeper understanding of the structure and function of catalysts. The project made extensive use of synchrotron radiation, specifically X-ray microscopy and tomography as emerging methods in catalysis research. This success on the European level highlights the leading role which synchrotron science has to play in the study of matter.

Catalysis plays a crucial role in sustainable chemical production, chemical energy conversion and storage, among many others, and is a key technology area in synchrotron radiation research. During his PhD work at Karlsruhe Institute of Technology, Sebastian Weber studied catalysts for CO₂ methanation using spatially-resolved characterisation tools including X-ray microscopy and tomography. These diverse X-ray imaging methods were exploited to study the 3D structure of catalytic materials over a range of length scales, addressing various levels of hierarchical structural features which are critical to understanding catalyst performance. This topic is a special focus of the Young Investigator Group of Dr. Thomas Sheppard at KIT, who supervised and secured funding for the project, within the wider group of Prof. Jan-Dierk Grunwaldt.

Only a handful of research groups worldwide are currently active in the field of X-ray microscopy applied to catalysis research, highlighting the emerging role of this vibrant research field. During his PhD work, Sebastian Weber in particular worked to develop applications of hard X-ray ptychography and ptychographic X-ray tomography (PXCT) to study catalyst pore structures, structural evolution under reaction conditions, and the effects of catalyst deactivation. These methods routinely reach spatial resolution below 50 nanometres (0.001 x diameter of a human hair), and have been applied so far on samples up to 50 micron in diameter (ca. the diameter of a human hair). The further development of ptychography holds excellent potential for catalysis and materials research, particularly in the age of fourth generation light sources with improved coherence and decreased source emittance. The project resulted in several high quality publications in leading chemistry and materials journals, reflecting the knowledge gained regarding 3D structure of catalysts, and the potential for development of improved catalysts in future.

Sebastian Weber recently completed his doctorate with the title “Revealing Porosity and Structure of Ni-based Catalysts for Dynamic CO₂ Methanation with Hard X-rays”, earning a distinction from KIT. Now his work was further recognised by securing the Gold Medal of the European Young Chemists’ Award at PhD level. The award is presented every two years during the EuChemS Chemistry Congress on behalf of the Società Chimica Italiana (SCI) and the European Chemical Society (EuChemS). The prize highlights excellent research from young / early stage researchers across all fields of chemistry and chemical sciences, and is therefore a highly competitive prize. After a pre-selection phase based on scientific excellence, the six finalists each held a presentation at the EuChemS Chemistry Congress in Lisbon, Portugal. The award not only highlights the excellent contribution of Sebastian Weber to the field of chemical sciences, but promotes in front a broad audience the essential role of synchrotron radiation in delivering future insights and innovations across the field of natural sciences.

Related articles on this research can be found in the Diamond Annual Review 2021-2022, “X-ray ptychography investigates coking of solid catalysts in 3D”, p.66-67, and on the DESY website

Image: Award ceremony during the 8^th EuChemS Chemistry Congress in Lisbon, Portugal, Sebastian Weber (KIT, left), Prof. Floris Rutjes (President of the European Chemical Society, middle) and Prof. Angela Agostiano (Chair of the EYCA Award Committee, right).

Graphics: EYCA

Targeting a parasite’s DNA could be more effective way to treat malaria

2022/08/082022/08/11

Research from the University of Sheffield using Diamond has explored a new way of killing the Plasmodium parasite that causes malaria.

According to the World Health Organisation, there were 241 million cases of malaria and 627,000 deaths worldwide in 2020 – making the study and treatment of this disease a high-priority issue for scientists around the world. In a feasibility study, researchers from the University of Sheffield used Diamond to reveal a novel way of fighting the life-threatening disease, malaria. The study discovered molecules that interfered with the parasite’s DNA processing enzyme, but not the equivalent human one.

A research team from the University of Sheffield’s Department of Infection, Immunity and Cardiovascular Disease examined and targeted an enzyme that maintains the classic double-helical structure of the malaria parasite’s DNA, which contains the blueprint of life, which could be a more effective way to combat malaria.

Image: A flap endonuclease cuts DNA (the orange intertwined worms), credit University of Sheffield

A new leap in understanding nickel oxide superconductors

2022/07/252022/07/28

Researchers discover they contain a phase of quantum matter, known as charge density waves, that’s common in other unconventional superconductors. In other ways, though, they’re surprisingly unique.

BY GLENNDA CHUI

A new study shows that nickel oxide superconductors, which conduct electricity with no loss at higher temperatures than conventional superconductors do, contain a type of quantum matter called charge density waves, or CDWs, that can accompany superconductivity.

The presence of CDWs shows that these recently discovered materials, also known as nickelates, are capable of forming correlated states – “electron soups” that can host a variety of quantum phases, including superconductivity, researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University reported in Nature Physics today.

“Unlike in any other superconductor we know about, CDWs appear even before we dope the material by replacing some atoms with others to change the number of electrons that are free to move around,” said Wei-Sheng Lee, a SLAC lead scientist and investigator with the Stanford Institute for Materials and Energy Science (SIMES) who led the study.

“This makes the nickelates a very interesting new system – a new playground for studying unconventional superconductors.”

Nickelates and cuprates

In the 35 years since the first unconventional “high-temperature” superconductors were discovered, researchers have been racing to find one that could carry electricity with no loss at close to room temperature. This would be a revolutionary development, allowing things like perfectly efficient power lines, maglev trains and a host of other futuristic, energy-saving technologies.

But while a vigorous global research effort has pinned down many aspects of their nature and behavior, people still don’t know exactly how these materials become superconducting.

So the discovery of nickelate’s superconducting powers by SIMES investigators three years ago was exciting because it gave scientists a fresh perspective on the problem.

Since then, SIMES researchers have explored the nickelates’ electronic structure – basically the way their electrons behave – and magnetic behavior. These studies turned up important similarities and subtle differences between nickelates and the copper oxides or cuprates – the first high-temperature superconductors ever discovered and still the world record holders for high-temperature operation at everyday pressures.

Since nickel and copper sit right next to each other on the periodic table of the elements, scientists were not surprised to see a kinship there, and in fact had suspected that nickelates might make good superconductors. But it turned out to be extraordinarily difficult to construct materials with just the right characteristics.

“This is still very new,” Lee said. “People are still struggling to synthesize thin films of these materials and understand how different conditions can affect the underlying microscopic mechanisms related to superconductivity.”

Image: An illustration shows a type of quantum matter called charge density waves, or CDWs, superimposed on the atomic structure of a nickel oxide superconductor. (Bottom) The nickel oxide material, with nickel atoms in orange and oxygen atoms in red. (Top left) CDWs appear as a pattern of frozen electron ripples, with a higher density of electrons in the peaks of the ripples and a lower density of electrons in the troughs. (Top right) This area depicts another quantum state, superconductivity, which can also emerge in the nickel oxide. The presence of CDWs shows that nickel oxides are capable of forming correlated states – “electron soups” that can host a variety of quantum phases, including superconductivity.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

Antibody rigidity regulates immune activity

2022/07/132022/07/15

Scientists at the University of Southampton have gained unprecedented new insight into the key properties of an antibody needed to stimulate immune activity to fight off cancer, using the ESRF’s structural biology beamlines, among others.

The interdisciplinary study, published in Science Immunology, revealed how changing the flexibility of the antibody could stimulate a stronger immune response. The findings have enabled the team to design antibodies to activate important receptors on immune cells to “fire them up” and deliver more powerful anti-cancer effects. The researchers believe their findings could pave the way to improve antibody drugs that target cancer, as well as automimmune diseases.

In the study, the team investigated antibody drugs targeting the receptor CD40 for cancer treatment. Clinical development has been hampered by a lack of understanding of how to stimulate the receptors to the right level. The problem being that if antibodies are too active they can become toxic. Previous research by the same team had shown that a specific type of antibody called IgG2 is uniquely suited as a template for pharmaceutical intervention, since it is more active than other antibody types. However, the reason why it is more active had not been determined. What was known, however, is that the structure between the antibody arms, the so called hinges, changes over time.

This latest research harnesses this property of the hinge and explains how it works: the researchers call this process “disulfide-switching”. In their study, the team analysed the effect of modifying the hinge and used a combination of biological activity assays, structural biology, and computational chemistry to study how disulfide switching alters antibody structure and activity.

Image: Flexibility of the monoclonal antibody F(ab) arms is conferred by the hinge region disulphide structure

Credit: C. Orr

Synchrotron science through board games!

2022/07/012022/07/21

Learning how to communicate your science is an essential part of any scientist’s career. Whether for an interview, a presentation or for sharing your latest research with family and friends, there are many routes to explore. However, have you ever considered a board game…?

It is definitely an unusual form of public engagement, but it is one that has been an incredibly rewarding experience for us all. The ‘we’ here is Mark Basham, Claire Murray (both from Diamond Light Source) and Matthew Dunstan (University of Cambridge), who had never worked together before this project. However, we quickly became good friends and collaborators in the process of creating our board game to engage teenagers in the life of a scientist and in STEM careers. The game is based on the floor plan of Diamond Light Source and every experiment is one that has been carried out there. We playtested our game with lots of family and friends before taking it to our target audience – teenagers between 12-18 who may not be aware of the full variety of careers in STEM available to them. We learned so much that we have actually just published a paper sharing the design process, evaluation and results and our approach to inclusive design. Check out the Diamond website to learn more about it!

New Director for massive upgrade into Diamond-II

2022/06/072022/06/07

To cement its position as a world-leading research facility, Diamond Light Source recently revealed plans for a large upgrade called Diamond-II and that is set to strengthen the UK’s global scientific leadership. This will be a transformational upgrade that will enable a huge expansion of UK science capabilities as it involves a coordinated programme of development combining state-of-the-art technology in a new machine, five new flagship beamlines and a comprehensive series of upgrades to its Instruments.

To lead this programme, Diamond has appointed Rob Walden, a Chartered Engineer with over 20 years’ experience in delivering business and process improvement programmes in the aerospace manufacturing engineering industry. This was followed by several years as a senior projects advisor in central government where he was involved in, and delivered, nationwide policy projects as well as helping to develop the programme delivery framework for government. Rob was also part of the Cabinet Office’s Gateway Assurance review team and conducted a number of forensic assurance delivery reviews for programmes of national interest. Additionally, he helped to set up the national programme office structure for Highways England and ran two busy Project Management Offices.

Rob joined Diamond Light Source from Sellafield Ltd where he focused on raising the standards of the programme delivery framework, which included the appointment and development of the SRO (Senior Responsible Officer) function for major projects of national interest. Rob comments:

Image: Rob Walden, programme director for Diamond-II

Credit: Diamond Light Source

Extending the longevity of perovskite solar cells for cheaper solar energy

2022/05/252022/05/26

Study reveals the secret to treating the ‘Achilles’ heel’ of alternatives to silicon solar panels for the photovoltaics industry

Diamond’s Nanoprobe beamline I14 and the electron Physical Science Imaging Centre (ePSIC) were used by a multidisciplinary team of researchers to gain new insight into the perovskite materials that hold so much potential in the field of optoelectronics. Focusing on structural changes that can lead to degradation, the Diamond instruments were part of a suite that enabled the group to observe the nanoscale properties of thin films of perovskite materials and how they change over time under solar illumination. The research, recently published in Nature, could significantly accelerate the development of long-lasting, commercially available perovskite photovoltaics.

Perovskite materials offer a cheaper alternative to silicon for producing solar cells and also show great potential for other optoelectronic applications, such as energy efficient LEDs and X-ray detectors.

The metal halide salts are abundant and much cheaper to process than crystalline silicon. They can be prepared in a liquid ink that is simply printed to produce a thin film of the material.

While the overall energy output of perovskite solar cells can often meet or – in the case of multi-layered, so-called ‘tandem’ devices – exceed that achievable with traditional silicon photovoltaics, the limited longevity of the devices is a key barrier to their commercial viability.

A typical silicon solar panel, like those you might see on the roof of a house, typically lasts about 20-25 years without significant performance losses.

Because perovskite devices are much cheaper to produce, they may not need to have as long a lifetime as their silicon counterparts at least to enter some markets – but to fulfil their ultimate potential in realising widespread decarbonisation, cells will need to operate for at least a decade or more. Researchers and manufacturers have yet to develop a device with similar stability to silicon cells.

Now, researchers at the Department of Chemical Engineering and Biotechnology (CEB) and Cavendish Laboratory at the University of Cambridge, together with the Okinawa Institute of Science and Technology (OIST) in Japan, have discovered that the defects that limit perovskite efficiency are also responsible for structural changes in the material that lead to degradation.

Image: A typical silicon solar panel, like those you might see on the roof of a house, typically lasts about 20-25 years without significant performance losses

#SynchroLightAt75 campaign launches on International Day of Light

2022/05/162022/05/16

The SRS at Daresbury Laboratory in the UK was the world’s first dedicated synchrotron light source facility. It opened in 1980 and delivered worldwide impact and two Nobel Prizes.

The first of its kind, the SRS enabled research that has improved the quality of our lives in so many ways. This included research into diseases such as HIV and AIDS, as well as motor neurone disease, to name just a few examples. The structure of the Foot & Mouth virus was solved for the first time at the SRS – it was the first animal virus structure to be determined in Europe and led to the development of a vaccine. The huge magnetic memory of the Apple iPod was also the result of research carried out on the SRS. However, its most famous achievement was the key role it played towards a share of two Nobel Prizes in Chemistry. One to Sir John Walker in 1997, for solving a structure of an enzyme that opened the way for new insights into metabolic diseases, and the other to Sir Venki Ramakrishnan in 2009, for his work on the structure and function of the Ribosome, the particle responsible for protein synthesis in living cells.

During its lifetime, the SRS created a critical mass of highly skilled engineers and technicians at Daresbury Laboratory, with specialisms ranging from detectors to magnets and electronics, and by the time it closed in 2008, it had collaborated with almost every country active in scientific research. It had hosted over 11,000 users from academia, government laboratories and industry worldwide, leading to the publication of more than 5000 research papers, resulting in numerous patents. The economic impact of this was vast on a worldwide scale, but it also played an important role in boosting the regional economy of the North West, having worked with hundreds of local businesses.

The success of the SRS led to the development of many similar machines around the world, with the technologies and skills developed still in use at many facilities today, including its UK successor, the Diamond Light Source at Harwell Science and Innovation Campus in Oxfordshire. It also led to the establishment of ASTeC, a leading centre for accelerator science and technology at Daresbury Laboratory, and the Cockcroft Institute, a joint venture between STFC and the Universities of Lancaster, Liverpool, Manchester and Strathclyde. It is also home to CLARA, a unique particle accelerator designed to develop, test and advance accelerator technologies of the future. Research carried out by accelerator scientists at Daresbury has had many impacts, particularly in the health and medicine arena, including work to develop our next generation of proton imaging technology for cancer detection, and research that could one day lead to more efficient diagnoses of cervical, oesophageal, and prostate cancers. In the footsteps of senior scientist, Professor Ian Munro, who was responsible for the plan to build the SRS and for its operation at Daresbury, ASTeC’s accelerator scientists and engineers continue to play a key role in designing, building and upgrading the world’s newest generations of accelerator facilities.

Metal-Organic Frameworks can capture toxic air pollutants

2022/02/232022/03/03

The air that we breathe

According to the World Health Organisation¹ (WHO), 92% of people worldwide live in places with poor air quality, and outdoor air pollution causes 4.2 million deaths a year, with another 3.8 million caused by indoor air pollution.

Figures published by Public Health England² showed that the health and social care costs of air pollution in England alone were £42.88 million in 2017 and could reach £5.3 billion by 2035.

There are many different types of air pollution, which arise from a wide range of sources. In the UK, five types are of particular concern:

The mixture of liquid droplets and solid particles found in the air is called particulate matter (PM). Some PM comes from natural sources (e.g., pollen, sea spray and desert dust), but it also includes dust from car exhausts, brakes and tyres and smoke. PM is classified according to size, with PM2.5 (particles less than 2.5 micrometres across) able to reach and damage the lungs and other organs.
Volatile organic compounds (VOCs) are a range of organic molecules that display similar behaviour in the atmosphere. These include vapours from household products such as air fresheners, cleaning products and perfumes, as well as petrol and solvents.
Ammonia (NH₃) gas is mainly released from agricultural sources such as slurry, other rotting farm waste and fertilisers.
Nitrogen oxide (NO_x) gases, including nitrogen dioxide (NO₂), are mainly created by burning fossil fuels.
Sulphur dioxide (SO₂) is an acidic gas that can irritate airways, particularly in people with asthma.

SO₂ and NO₂ are both reactive, corrosive gases. Removing them from the air is challenging but would have enormous benefits for human health.

Can we clean up our act with MOFs?

Metal-Organic Frameworks (MOFs) are sponge-like materials that can adsorb and hold “guest” molecules. By fine-tuning their properties – pore size and geometry, framework topology and chemical functionality – they can be tailored for specific applications, including gas adsorption, separation, catalysis, substrate binding and delivery. MOFs containing open metal sites (OMSs), in particular, can provide highly selective adsorption of target gases.

However, stable MOFs with OMSs are rare, as are MOF materials that can reversibly adsorb SO₂ and NO₂. While there are already over 100,000 known MOFs (and over half a million structures have so far been predicted), screening each one individually for its suitability for this application would be time-consuming and costly. A far better approach is to improve our understanding of the mechanism of active sites within capture materials so that we can design or discover new functional MOF materials. This in itself is a challenging task, as host-guest interactions are often dynamic processes, where multiple binding sites of similar energies affect the movement of guest molecules in the pores.

Using synchrotron techniques, an international team of researchers has described the synthesis, crystal structure and gas adsorption and separation properties of a unique {Ni₁₂}- wheel-based MOF that exhibits high isothermal uptake of SO₂ and NO₂.

Using single crystal X-ray diffraction (SCXRD) at the Advanced Light Source in California and infrared (IR) single crystal micro-spectroscopy at Diamond’s B22 beamline, the team performed dynamic breakthrough experiments that confirmed the selective retention of SO₂ and NO₂ at low concentrations under dry conditions. Their results show, at a crystallographic resolution, a detailed molecular mechanism with reversible coordination of SO₂ and NO₂ at the six open Ni(II) sites on the {Ni₁₂}-wheel and at oxygen atom and ligand sites.

Image: Artist’s impression of the unique {Ni12}- wheel-based MOF in action, exhibiting high isothermal uptake of SO2 and NO2.

Credit: Dr Sihai Yang

New angle for perovskite research

2022/02/012022/02/03

Perovskite materials offer the potential for cheaper optoelectronic devices such as solar cells. Of these, the formamidinium (FA)-based FAPbI3 crystal is one of the most promising – it has a bandgap close to ideal and is very thermally stable. However, photoactive cubic (α)-FAPbI3 perovskite phase is highly unstable and quickly transforms into the non-perovskite yellow phase at room temperature in ambient atmosphere, which affects the performance of photovoltaic devices. Alloying of FA-based perovskite with caesium, methylammonium (MA) cations or a combination of both can keep the perovskite in its more efficient phase at lower temperatures. However, this can give patchy results, leading to power losses.

In work recently published in Science, researchers from the University of Cambridge Department of Chemical Engineering and Biotechnology (CEB) and the Cavendish Laboratory investigated the crystal structure of the alloyed perovskite materials to understand why adding cations improved their performance. Their results show that cation alloying induces a minor octahedral tilt that keeps the perovskite material in its highly efficient phase, and is a step towards commercial production of stable and efficient perovskite-based solar cells.

A small distortion makes a big difference

Formamidinium (FA)-based perovskites have much better thermal stability than the methylammonium (MA)-based absorber layers commonly used in early perovskite-based solar cells. FAPbI3 is a particularly promising material, but its photoactive phase is only stable at high temperatures (above 150ºC) in inert atmosphere. It transitions to a hexagonal phase with poor optoelectronic performance at lower temperatures. 

It has been shown empirically that alloying FAPbI3 with methylammonium (MA) cations or caesium (or both) improves stability. However, although this approach led to record efficiencies, the mechanism underlying it was not fully understood. It also produces uneven materials with patches of instability that lead to performance losses.

Co-lead author Tiarnan Doherty was a PhD student at the Cavendish Laboratory and is now an Oppenheimer Fellow in CEB. He says:

Image: Artist’s impression of formamidinium (FA)-based crystal

Credit: Tiarnan Doherty, University of Cambridge

More to life than light

2022/01/242022/01/24

The #LightSourceSelfies video campaign highlights the dedication and enthusiasm that is felt by those working in this field. To maintain a sense of physical and mental wellbeing, it is also important to make time for non-work related things like family, hobbies and interests. This montage, with contributors from the ESRF, ALS, MAX IV and Diamond, gives a flavour of the wide range of activities that those in the light source community enjoy when they are not working.