Diamond Concise Annual Review 2021/22

26 27 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 1 / 2 2 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 1 / 2 2 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. Two new flagship beamlines will be added to the Group as part of the Diamond-II programme: SWIFT (Spectroscopy WithIn Fast Timescales) is a high flux beamline optimised for the study of samples under operando conditions, and BERRIES (Bright Environment for x-ray Raman, Resonance Inelastic and Emission Spectroscopies), that will offer two new techniques to the Diamond user community: pink- beam X-ray Emission Spectroscopy (pink-XES) and X-ray Raman Scattering (XRS). This year’s studies included improving essential trace element yield in crops, optimising propene production frommethanol, and designing new catalysts withmetal-organic frameworks. Optimising selenium supplementation in crop plants Selenium is an essential trace element for human health and is taken in through eating appropriate foods such as wheat. Regions with low soil selenium levels provide inadequate dietary intake, and this affects up to 14% of the world’s population who remain at risk of developing chronic degenerative diseases. Soil fertilisation (biofortification) with selenium is practiced in different parts of the world but high levels can hamper the normal development of plants. A plant biostimulant can significantly reduce the stress experienced by wheat during selenium-biofortification processes. However, little was known about the effect of the biostimulant in the seleniummetabolisation pathways. A Spanish research team investigated selenium present in wheat grains using beamline I18 to gather data on the distribution of the elements and the chemical species present. The study showed that the biostimulant has a key role in enhancing both the number of grains produced per spike and their dry biomass without hindering the selenium enrichment process. Based on the successful results on wheat plants, similar enrichment studies are planned on other plants such as alfalfa. This information will be useful to minimise both plant toxicity and economic cost and move towards more effective and plant- healthy selenium supplementation. Xiao T et al. DOI: 10.1016/j.plaphy.2021.01.025 Improving propene production Propene is a key compound used in the production of a wide range of chemicals. With rapidly growing demand, the world faces a shortage of this crucial ingredient unless more efficient production methods can be developed. Commercial methanol-to-propene (MTP) plants use zeolite catalysts (ZSM- 5 and SAPO-34) to produce propene from methanol. However, this process is poorly understood and produces a range of by-products, such as coke which results in low propene selectivity and rapid catalyst deactivation. Investigations of the process and development of more selective and stable catalysts are important goals for ongoing MTP research. A team from the University of Manchester synthesised a new zeolite and used beamline I20-EDE to study the MTP reaction. They also used complementarymeasurements on beamline I11 to examine the configurations of adsorbed methanol molecules in zeolite pores. The results show that the new zeolite offers remarkable propene selectivity (51%), and catalytic stability (>50 hours) at full methanol conversion. Combining in situ synchrotron X-ray powder diffraction and X-ray absorption spectroscopy at Diamond with inelastic neutron scattering, the team was able to uncover key details of the process to add to fundamental understanding. This work will help develop sustainable manufacturing techniques using renewable resources such as biomass and CO 2 . Lin F et al. DOI: 10.1038/s41467-021-21062-1 Assessingmetal organic frameworks as catalysts The presence of metal species that can easily exchange their oxidation states is of paramount importance in the field of catalysis and photocatalysis, among others. Metal-organic frameworks (MOFs) are ideal candidates for these processes, and their synthesis is crucial if they are going to progress from laboratory curiosity to real applications. Researchers are developing synthetic routes to prepare bimetallic MOFs with redox properties. However, the preparation and characterisation of these mixed-metal MOFs are challenging. To understand the success of the synthesis and the MOFs’ properties, the local structure of the metal must be fully understood. A Spanish group used X-ray Absorption Spectroscopy on beamline I20 to define the local structure of the metal in operando . Using their results, the team has found a synthetic route to prepare true-mixed metal MOFs to modulate the crystal morphology and the electronic nature of the metal cations. Their results give us a new way to prepare bimetallic redox MOFs, which have the potential to be applied as catalysts in many different reactions, including selective hydrogenation, oxidation or Meerwein-Ponndorf-Verley reactions. Ronda-Lloret M et al. DOI: 10.1002/adfm.202102582