48 49 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 Imaging andMicroscopy Group DIAD Beamline Introducing DIAD, Diamond’s newDual Imaging And Diffraction beamline Materials – Technique Development Diamond’s newest fully operational beamline is DIAD, the Dual Imaging and Diffraction (DIAD) beamline. DIAD was born from a scientific need to simultaneously obtain the 3D microstructure of a material and local information about its phase composition and strain. DIAD’s unique dual-beam setup is the world’s first beamline that can quasi-simultaneously perform X-ray imaging and diffraction. The unique set up offers full/field imaging and tomography of 2D and 3D complex structures. Diffraction data is collected by a multi-axis robot arm mounted with a state-of-the-art Cd-Te Pilatus 3M detector (Fig 1). Users can perform spatially resolved phase identification; perform strain mapping using micro-diffraction (Fig 2); and perform in-situ and operando experiments that require spatially correlated results. Importantly, the simultaneous acquisition of imaging and diffraction data reduces lost down-time to mode switching, that is typical of other imaging and diffraction beamlines. Experimental workflows on DIAD, post-processing, and analysis pipelines can all be automated using innovative in-house software. Users can access advanced data acquisition strategies, analyse their data live, and ultimately make informed decisions about their science to maximise the potential of their experimental time. DIAD saw its First Light in December 2018 and welcomed its first User in February 2021. Since then, it has hosted a wide range of users across several fields including, but not limited to: • Medicine - The behaviour of arterial stents under changing pressure for better patient outcomes • Environment : The dynamic study of plant root behaviour in climate change affected soils • Energy –The operando spatial distribution of charge in Li-ion batteries. • Materials – Stress induced cracking in nuclear containment materials. In summary, users can simultaneously collect time- and spatially-resolved information on both the crystallographic micro-structure and material macro- structure. The DIAD beamline has the unrivalled capability to access multi- scale, multi-modal information, granting users the ability to investigate highly dynamic systems. Related publication: Reinhard, C. et al. Beamline K11 DIAD: A new instrument for dual imaging and diffraction at Diamond Light Source. Journal of Synchrotron Radiation 28 .6: 1985-1995 (2021). DOI: 10.1107/S1600577521009875 Funding acknowledgement: DIAD was part-funded by the University of Birmingham Corresponding author: Sharif Ahmed, Diamond Light Source,
[email protected] Fig2: 3D mapping of microscale and nanoscale compressive strain in Bovine tissue. Comparison of samples of unloaded (left grid) and 15 N compressive load (right grid). Figure highlights the multimodal capability of combined diffraction (raster-scanning mode) and tomography. Microscale structure (a,e); orientational texture (b,f ); integrated 004 peak intensity (c,g), and lattice spacing (d,h). Created in Avizo (Source - MG27983 E. Newham, H. Gupta & J. Tozzi). Fig1: Correlative SRCT and WAXD imaging at DIAD. (a) Annotated photograph showing moveable WAXD detector mounted on robot arm, and static SRCT objective. Developing new catalysts for green hydrogen peroxide production Physical Chemistry – Catalysis – Chemistry Hydrogen peroxide (H 2 O 2 ) is one of the top 100 most important chemicals globally, in high demand in both daily life and industrial processes, including disinfection, sanitisation, wastewater treatment, paper pulp bleaching, chemical synthesis and textile production. It is considered an excellent ‘green’ oxidant due to the absence of by- products (except water) upon use, relatively high redox potential, relative safety and low toxicity. However, the current industrial productionmethod, the anthraquinone process, is energy- andwaste- intensive, requiring complex infrastructures. Therefore, a more eco- friendly and sustainablealternative technology for hydrogenperoxide production is needed. Selective electrocatalytic oxygen reduction reaction (ORR) via the 2-electron pathway appears to be an attractive and feasible route that enables portable, on-demand, and distributed hydrogen peroxide synthesis. However, hydrogen peroxide production through ORR requires highly active and selective electrocatalysts. Although platinum-group metals (PGMs) are known to be state-of-the-art ORR catalysts, their scarceness and low mass activity significantly hinder their practical use, calling for alternative electrocatalysts. Single-atom catalysts (SACs) have the potential for catalysing the ORR. However, they suffer from limited activity and selectivity, and we currently lack methods to improve their performance. Therefore, it is important to develop synthetic strategies to obtain SACs with tuned coordination environments and electronic structures that can enhance catalytic performance for realising highly efficient hydrogen peroxide electrosynthesis. A team of researchers from China performed Annular Dark-Field Scanning TEM (ADF-STEM) at ePSIC as part of a project to develop a highly selective and active Co-N-C electrocatalyst for hydrogen peroxide electrosynthesis. The setup at ePSIC enabled them to minimise the sample damage caused by the electron beam and identify the metal atoms dispersed on the graphene support as bright dots. The team successfully developed a facile and transient microwave irradiation treatment to simultaneously achieve the regulation of the coordination number and the surrounding oxygenated functional groups in cobalt-nitrogen-carbon SACs. The as-prepared catalyst possesses a low- coordinated Co-N 2 configuration and high content of C-O-C epoxide groups (Co-N 2 -C/HO). Compared to the conventional Co-based SAC, Co-N 2 -C/HO shows a significantly enhanced performance for hydrogen peroxide production with a high selectivity, prominent mass activity and large kinetic current density, making it one of the most active SACs for hydrogen peroxide electrosynthesis. Considering the generality of the present synthetic methodology, this work offers a pathway toward the exploration of catalysts with unconventional structure and composition for catalysing reactions beyond ORR, such as CO 2 reduction and N 2 reduction reactions. Related publication: Gong, H. et al . Low-coordinated Co-N-C on oxygenated graphene for efficient electrocatalytic H 2 O 2 production. Advanced Functional Materials 32 , 2106886 (2022). DOI: 10.1002/adfm.202106886 Funding acknowledgement: National Natural Science Foundation of China, grant number 51902099 Corresponding authors: Huilong Fei, Hunan University,
[email protected] Imaging andMicroscopy Group ePSIC (a) ADF-STEM image of the graphene supported Co-N 2 -C/HO catalyst, revealing that the Co metals are dispersed as individual atoms highlighted by the yellow circles. (b) Scheme of the structural model for the Co-N 2 -C/HO catalyst, where the Co atom is coordinated to two N atoms and one O atom and the graphene substrate is decorated with epoxy groups. The green, grey, dark blue, red, and blue spheres represent the H, C, N, O, Co atom, respectively.