Diamond Light Source - Annual Review 2022/23 - Concise Edition

30 31 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 2 / 2 3 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 2 / 2 3 Spectroscopy Group T he Diamond Spectroscopy Group consists of four beamlines: the Microfocus Spectroscopy beamline (I18), the Core EXAFS beamline (B18), and the two independently operating branches of the Versatile X-ray Absorption Spectroscopy beamline, I20-Scanning and I20- EDE. These spectrometers are highly complementary, most notably in the energy ranges they cover, the size of their focussed beam spots, and the time resolutions they can reach. This complementarity means that they can support research across many different scientific disciplines, from chemistry and catalysis through materials science, condensed matter physics, environmental and life science, and cultural heritage. The fast-scanning capabilities of the I20-EDE beamline will be covered by the new spectroscopy beamline that will be built as part of the Diamond-II upgrade programme. The newbeamline, called SWIFT (SpectroscopyWithIn Fast Timescales) will be awiggler-based, quick- scanning EXAFS beamline dedicated to operando studies, also atmicrometric scale. This year’s studies included investigating catalyst for green chemistry, understanding superconductors damage under irradiation, and optimising sodium-ion batteries. Control of zeolitemicroenvironment for biomass conversion Pentadienes serve as key building blocks for the chemical and polymer industries and are widely used as monomers in the production of adhesives, plastics, and resins. However, state-of-the art processes to produce pentadienes rely on fossil fuels. Therefore, the sustainable production of pentadienes from renewable resources is a vitally important and urgent task. Methyltetrahydrofuran (2-MTHF) can be produced readily from lignocellulose-derived furfural and has been identified as a sustainable resource for making pentadienes. Leading catalysts for this reaction include amorphous SiO 2 /Al 2 O 3 , and Al or B- zeolites. MCM-41 is a mesoporous silica-based material used as a catalyst or catalyst support for a wide range of reactions; emerging niobium-based catalysts have shown exceptional performance for the hydrodeoxygenation of biomass under mild conditions. The research team aimed to determine the full molecular details of the catalytic mechanism through the use of operando X-ray Absorption Spectroscopy (XAS), combined with Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and in situ high-field solid-state Nuclear Magnetic Resonance spectroscopy on Diamond I20-EDE beamline. This work reported the synthesis of a series of new (Al,Nb)-bimetallic mesoporous silica materials for the first time. AlNb-MCM-41(35/1/0.9) shows excellent catalytic performance for converting biomass-derived 2-MTHF to pentadienes. The direct transformation of biomass derivatives to C5 dienes under mild conditions described in this study will have a significant impact on the development of future sustainable chemical processes. Fan, M. et al. DOI: 10.1002/anie.202212164 Investigating the damage tolerance of superconductors for fusion power plants High-temperature superconductors are an essential component of compact tokamak fusion reactors, which promise to provide a commercial route towards fusion power plants by the mid-2030s. Researchers sought to discover what kinds of defects are generated by irradiation with energetic particles in the high-temperature superconducting tapes used tomake demonstrator fusionmagnets by companies such asTokamak Energy and Commonwealth Fusion Systems. Superconductivity in high-temperature superconductors is strongly suppressed by structural disorder. When neutrons or other energetic particles collide with atoms in the superconductor, some get knocked out of position, creating defects in the crystal that reduce superconductivity. Using high energy resolution X-ray Spectroscopy, the I20-Scanning beamline allowed the team to probe changes in the local chemical bonding environment around the copper atoms that occur when oxygen atoms move to different sites in the structure. The researchers identified specific crystal defects that may be responsible for the loss of superconductivity. Their results gave conclusive evidence for the first time that irradiation produces considerable changes to the environment surrounding the copper atoms that reside in the superconducting planes of the crystal. Comparing the nature of the defects created in high-temperature superconductors under irradiation by different kinds of energetic species, and at different temperatures, is a key part of being able to predict how these materials will behave in operation in a real fusion device. The fundamental understanding gained from these experiments will lead to more robust interpretation of a range of irradiation data. Ultimately, the hope is that it will provide magnet designers withmore reliable information. Nicholls, RJ. et al. DOI: 10.1038/s43246- 022-00272-0 Developing a deeper understanding of electrodematerials for sodium-ion batteries Various materials can be used as electrodes in sodium-ion batteries (SIBs). Researchers from Germany used X-ray Absorption Spectroscopy (XAS) on Diamond’s B18 beamline as part of a rigorous study of the sodium storage properties of ultra-small Fe 3 S 4 nanoparticles. This material exhibits excellent electrochemical performance as an anode material for SIBs. Previous research had shown different structural phase transformations during the discharge and charge of the anode material. For a more detailed understanding, the researchers needed to analyse the local structure around the elements Fe and S and their oxidation states, in the pristine nanocrystalline material andduringcharginganddischarging. Suchelement-specific information, combined with other techniques ( e.g. , to determine the crystallographic structure), can yield important insights into the reaction mechanism of a battery material duringoperationand allowoptimisationof battery cells, e.g. , by tailoring materials properties or by adjusting cut-off potentials. Their results showed that the Na storage mechanism of this anode material can be attributed to cationic redox chemistry involving Fe. The experiments revealed the oxidation states of both elements at specific discharge/charge voltages. Using this information, the researchers were able to explain the long- term cycle stabilities of Na/Fe 3 S 4 cells during cycling to different lower cut-off potentials. Such studies can be used to find root causes for cell failure, precisely adjust battery cell limits and find optimal cycling conditions to improve the electrochemical performances and battery lifetime. Hartmann, F. et al. DOI:10.1039/D1NR06950K