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Establishing new energy-saving systems for gas separation using porous materials is indispensable for ensuring a sustainable future. Herein, we show that ELM-11 ([Cu(BF 4 ) 2 (4,4′-bipyridine) 2 ] n ), a member of flexible metal–organic frameworks (MOFs), exhibits rapid responsiveness to a gas feed and an ‘intrinsic thermal management’ capability originating from a structural deformation upon gas adsorption (gate-opening). These two characteristics are suitable for developing a pressure vacuum swing adsorption (PVSA) system with rapid operations. A combined experimental and theoretical study reveals that ELM-11 enables the high-throughput separation of CO 2 from a CO 2 /CH 4 gas mixture through adiabatic operations, which are extreme conditions in rapid pressure vacuum swing adsorption. We also propose an operational solution to the ‘slipping-off’ problem, which is that the flexible MOFs cannot adsorb target molecules when the partial pressure of the target gas decreases below the gate-opening pressure. Furthermore, the superiority of our proposed system over conventional systems is demonstrated. Separation processes in industry use substantial energy and energy-efficient purification systems should be developed for sustainability. Here the authors report a flexible metal–organic framework for high-throughput separation of CO 2 from a CO 2 /CH 4 gas mixture in a pressure vacuum swing adsorption system.

Water is the only available fossil-free source of hydrogen. Splitting water electrochemically is among the most used techniques, however, it accounts for only 4% of global hydrogen production. One of the reasons is the high cost and low performance of catalysts promoting the oxygen evolution reaction (OER). Here, we report a highly efficient catalyst in acid, that is, solid-solution Ru‒Ir nanosized-coral (RuIr-NC) consisting of 3 nm-thick sheets with only 6 at.% Ir. Among OER catalysts, RuIr-NC shows the highest intrinsic activity and stability. A home-made overall water splitting cell using RuIr-NC as both electrodes can reach 10 mA cm −2 geo at 1.485 V for 120 h without noticeable degradation, which outperforms known cells. Operando spectroscopy and atomic-resolution electron microscopy indicate that the high-performance results from the ability of the preferentially exposed {0001} facets to resist the formation of dissolvable metal oxides and to transform ephemeral Ru into a long-lived catalyst. Ru is one of the most active metals for oxygen evolution reaction, but it quickly dissolves in acidic electrolyte particularly in nanosized form. Here, the authors show that coral-like solid-solution Ru‒Ir consisting of 3 nm-thick sheets with only 6 at% Ir is a long-lived catalyst with high activity.

Synchrotron powder X-ray diffraction (PXRD) offers significant advantages in the structural analysis of functional materials and enables the acquisition of high-quality data; however, accurate data collection remains challenging for samples consisting of coarse crystallites or molten samples. Specifically, obtaining reliable PXRD data from samples in their as-solidified or non-pulverized state remains challenging during melting–solidification and crystal grain growth processes, as well as for materials produced by these processes. To mitigate these limitations, a two-axis rotation Gandolfi-type attachment—comprising a 45°-tilted φ -axis and its rotational ω -axis—was developed and implemented on a high-resolution powder diffractometer at SPring-8, which is equipped with fast area detectors. This configuration improved the particle statistics by increasing the number of crystallites satisfying the Bragg condition through two-axis rotation, while also stabilizing the sample position, even for molten samples, owing to the tilted geometry. Specifically, the integration of a high-speed spinner and multiple two-dimensional photon-counting detectors allowed sub-second continuous imaging and frame-by-frame peak separation, facilitating the indexing of PXRD data for complex structures. The analytical capability was evaluated in three case studies, namely the pair distribution function analysis of molten Zn, in situ observations of LiCoO 2 electrode material synthesis in a molten flux, and high-resolution PXRD of mineral crystals within a short timeframe. The results confirmed that the Gandolfi-type attachment improved data quality and reproducibility, thereby enabling reliable measurements even for practical samples with limited availability of fine powders.

Clarifying dynamic processes of materials is an important research topic in materials science. Time-resolved X-ray diffraction is a powerful technique for probing dynamic processes. To understand the dynamics, it is essential to analyze time-series data using appropriate time-evolution models and accurate start times of dynamic processes. However, conventional analyses based on non-linear least-squares fitting have difficulty both evaluating time-evolution models and estimating start times. Here, we establish a Bayesian framework including time-evolution models. We investigate an adsorption process, which is a representative dynamic process, and extract information about the time-evolution model and adsorption start time. The information enables us to estimate adsorption properties such as rate constants more accurately, thus achieving more precise understanding of dynamic adsorption processes. Our framework is highly versatile, can be applied to other dynamic processes such as chemical reactions, and is expected to be utilized in various areas of materials science.

Binary solid-solution alloys generally adopt one of three principal crystal lattices—body-centred cubic (bcc), hexagonal close-packed (hcp) or face-centred cubic (fcc) structures—in which the structure is dominated by constituent elements and compositions. Therefore, it is a significant challenge to selectively control the crystal structure in alloys with a certain composition. Here, we propose an approach for the selective control of the crystal structure in solid-solution alloys by using a chemical reduction method. By precisely tuning the reduction speed of the metal precursors, we selectively control the crystal structure of alloy nanoparticles, and are able to selectively synthesize fcc and hcp AuRu 3 alloy nanoparticles at ambient conditions. This approach enables us to design alloy nanomaterials with the desired crystal structures to create innovative chemical and physical properties. The crystal structure of a solid-solution alloy is generally determined by its elemental composition, limiting synthetic control over the alloy’s properties. Here, the authors are able to selectively control the crystal structure of Au–Ru alloy nanoparticles by rationally tuning the reduction speed of the metal precursors.

Recently, there has been a high demand for elucidating kinetics and visualizing reaction processes under extreme dynamic conditions, such as chemical reactions under meteorite impact conditions, structural changes under nonequilibrium conditions, and in situ observations of dynamic changes. To accelerate material science studies and Earth science fields under dynamic conditions, a submillisecond in situ X‐ray diffraction measurement system has been developed using a diamond anvil cell to observe reaction processes under rapidly changing pressure and temperature conditions replicating extreme dynamic conditions. The development and measurements were performed at the high‐pressure beamline BL10XU/SPring‐8 by synchronizing a high‐speed hybrid pixel array detector, laser heating and temperature measurement system, and gas‐pressure control system that enables remote and rapid pressure changes using the diamond anvil cell. The synchronized system enabled momentary heating and rapid cooling experiments up to 5000 K via laser heating as well as the visualization of structural changes in high‐pressure samples under extreme dynamic conditions during high‐speed pressure changes. A submillisecond X‐ray diffraction measurement system targeted at microscopic samples in a diamond anvil cell has been developed at BL10XU/SPring‐8. This system has enabled the visualization of structural changes of high‐pressure samples in the diamond anvil cell during instantaneous heating and quenching experiments combined with laser heating and during instantaneous compression and decompression experiments using a two‐line gas‐pressure control system, with a resolution in the submillisecond range.

The demand for powder X‐ray diffraction analysis continues to increase in a variety of scientific fields, as the excellent beam quality of high‐brightness synchrotron light sources enables the acquisition of high‐quality measurement data with high intensity and angular resolution. Synchrotron powder diffraction has enabled the rapid measurement of many samples and various in situ/operando experiments in nonambient sample environments. To meet the demands for even higher throughput measurements using high‐energy X‐rays at SPring‐8, a high‐throughput and high‐resolution powder diffraction system has been developed. This system is combined with six sets of two‐dimensional (2D) CdTe detectors for high‐energy X‐rays, and various automation systems, including a system for automatic switching among large sample environmental equipment, have been developed in the third experimental hutch of the insertion device beamline BL13XU at SPring‐8. In this diffractometer system, high‐brilliance and high‐energy X‐rays ranging from 16 to 72 keV are available. The powder diffraction data measured under ambient and various nonambient conditions can be analysed using Rietveld refinement and the pair distribution function. Using the 2D CdTe detectors with variable sample‐to‐detector distance, three types of scan modes have been established: standard, single‐step and high‐resolution. A major feature is the ability to measure a whole powder pattern with millisecond resolution. Equally important, this system can measure powder diffraction data with high Q exceeding 30 Å−1 within several tens of seconds. This capability is expected to contribute significantly to new research avenues using machine learning and artificial intelligence by utilizing the large amount of data obtained from high‐throughput measurements. A high‐throughput and high‐resolution powder X‐ray diffractometer has been developed in the third experimental hutch of BL13XU, SPring‐8. The diffractometer is equipped with six sets of 2D CdTe detectors and an automation system including sample exchange and equipment switching. Performance and demonstration results are presented.

Flexible metal–organic frameworks (MOFs) exhibiting adsorption-induced structural transition can revolutionise adsorption separation processes, including CO 2 separation, which has become increasingly important in recent years. However, the kinetics of this structural transition remains poorly understood despite being crucial to process design. Here, the CO 2 -induced gate opening of ELM-11 ([Cu(BF 4 ) 2 (4,4’-bipyridine) 2 ] n ) is investigated by time-resolved in situ X-ray powder diffraction, and a theoretical kinetic model of this process is developed to gain atomistic insight into the transition dynamics. The thus-developed model consists of the differential pressure from the gate opening (indicating the ease of structural transition) and reaction model terms (indicating the transition propagation within the crystal). The reaction model of ELM-11 is an autocatalytic reaction with two pathways for CO 2 penetration of the framework. Moreover, gas adsorption analyses of two other flexible MOFs with different flexibilities indicate that the kinetics of the adsorption-induced structural transition is highly dependent on framework structure. The kinetics of guest-induced structural transition shown by flexible metal–organic frameworks (MOFs) remain poorly understood despite being crucial for process design. Here, three MOFs are studied to reveal the framework-dependent kinetic nature.

The chemical order and disorder of solids have a decisive influence on the material properties. There are numerous materials exhibiting chemical order/disorder of atoms with similar X-ray atomic scattering factors and similar neutron scattering lengths. It is difficult to investigate such order/disorder hidden in the data obtained from conventional diffraction methods. Herein, we quantitatively determined the Mo/Nb order in the high ion conductor Ba 7 Nb 4 MoO 20 by a technique combining resonant X-ray diffraction, solid-state nuclear magnetic resonance (NMR) and first-principle calculations. NMR provided direct evidence that Mo atoms occupy only the M 2 site near the intrinsically oxygen-deficient ion-conducting layer. Resonant X-ray diffraction determined the occupancy factors of Mo atoms at the M 2 and other sites to be 0.50 and 0.00, respectively. These findings provide a basis for the development of ion conductors. This combined technique would open a new avenue for in-depth investigation of the hidden chemical order/disorder in materials. Chemical order/disorder in materials can be difficult to determine for atoms with similar X-ray scattering factors and neutron scattering lengths. Here authors use resonant XRD and NMR to elucidate hidden Mo/Nb chemical order in disordered hexagonal perovskite Ba 7 Nb 4 MoO 20 , with Mo atoms found to be localized near the ion-conducting oxygen deficient layer.

Developing artificial porous systems with high molecular recognition performance is critical but very challenging to achieve selective uptake of a particular component from a mixture of many similar species, regardless of the size and affinity of these competing species. A porous platform that integrates multiple recognition mechanisms working cooperatively for highly efficient guest identification is desired. Here, we designed a flexible porous coordination polymer (PCP) and realised a corrugated channel system that cooperatively responds to only target gas molecules by taking advantage of its stereochemical shape, location of binding sites, and structural softness. The binding sites and structural deformation act synergistically, exhibiting exclusive discrimination gating (EDG) effect for selective gate-opening adsorption of CO 2 over nine similar gas molecules, including N 2 , CH 4 , CO, O 2 , H 2 , Ar, C 2 H 6 , and even higher-affinity gases such as C 2 H 2 and C 2 H 4 . Combining in-situ crystallographic experiments with theoretical studies, it is clear that this unparalleled ability to decipher the CO 2 molecule is achieved through the coordination of framework dynamics, guest diffusion, and interaction energetics. Furthermore, the gas co-adsorption and breakthrough separation performance render the obtained PCP an efficient adsorbent for CO 2 capture from various gas mixtures. Developing porous systems with high molecular recognition performance can be challenging. Here the authors present a corrugated channel system that cooperatively responds to only CO 2 molecules over nine other similar gas molecules.