Open Access

Show Abstract ▼

Abstract: Human skeletal samples burned between 200 and 1000 °C, in both aerobic and anaerobic conditions, were probed by synchrotron-based Extended X-ray Absorption Fine Structure with a view to interpret heat-induced variations in chemical composition and structure. Heat-prompted changes in Ca2+ first and second coordination shells were unveiled (regarding PO43−, CO32− and/or OH− ligands). A higher crystallinity degree was found for 800-1000 °C burning temperatures as compared to 200-700 °C, in agreement with the higher amount of organic components in moderately heated samples. The unique local structural information delivered by XAS, particularly on the Ca2+ coordination environment which determines bone's structural features and degree of crystallinity, enabled an improved understanding of the heat-elicited changes undergone by bone, not previously accessed by other techniques. This is an innovative study, with a high impact in forensic and bioarchaeological research, focused on the analysis of burned human skeletal remains.

Open Access

Show Abstract ▼

Abstract: Enantiorecognition is a fundamental process in bioscience, ruling most life-related processes. This work focuses on the physics underlying chiral recognition, suggesting that the electron-spin/molecular-handedness interaction plays an important role here. Results obtained exploiting three complementary experimental techniques are compared, where metal surfaces are functionalized using a chiral porphyrin (cPorf): (1) cyclic voltammetry is used to probe the handedness of the electrode surface exploiting a chiral redox couple; (2) spin-dependent electrochemistry measurements were performed using a ferromagnetic electrode as spin injector; (3) magnetoconductive atomic force microscopy measurements proved that the charge transport through cPorf bundles adsorbed on a nickel surface is spin-polarized (spin polarization percentage, SP%, ranging between 20% and 50%). Mueller matrix polarimetry (MMP) spectra confirmed that the electronic circular dichroism of cPorf in solid-state thin films is not merely apparent but is true. The overall experimental results suggest that spin plays a fundamental role in the enantiorecognition process, as a possible manifestation of the Naaman−Waldeck chiral-induced spin selectivity effect.

Show Abstract ▼

Abstract: Air pollution is one of the leading global health risks according to the World Health Organization (WHO). Addressing this problem requires a variety of technological solutions such three-way catalysis (TWC), which reduces the tailpipe emissions of gasoline engines. TWC accomplishes this by catalyzing reactions between CO, NO, unburnt hydrocarbons and remaining O2, converting them into less harmful gaseous products. Despite being a long-established technology, continuous innovation is still required to meet the increasingly stringent legislative standards that aim to limit emissions from cars. Since modern three-way catalysts already operate efficiently at elevated temperatures, research efforts have shifted towards improving the low-temperature activity of such catalysts and decreasing emissions slip during the cold-start phase of the engine. Achieving this goal requires a molecular understanding of the underlying catalytic processes, which provides a basis for the rational design and optimization of improved catalyst systems. A typical three-way catalyst consists of a ceramic monolithic substrate onto which a wash coat containing catalytically active material is applied. These typically contain Pd, Pt and Rh as active metals, a ceria-zirconia based oxygen storage component, and a range of catalytic and structural promoters, all supported on alumina which provides stability and a high internal surface area. During operation, the active metals catalyze various reactions in parallel, most notably CO oxidation, NO reduction and hydrocarbon oxidation. The ceria-based component plays a crucial role by storing and releasing oxygen, thereby providing oxygen buffering under fluctuating exhaust gas compositions. Ceria in contact with active metal sites can directly participate in catalytic reactions by supplying oxygen at the metal-ceria interface, which helps mitigate CO poisoning of the metal. Furthermore, ceria can enhance catalyst durability by stabilizing highly dispersed metal species and preventing their agglomeration. The synergy of these functions makes ceria a highly effective promoter in three-way catalysis. Ceria-based catalysts in which the metal is highly or even atomically dispersed have attracted considerable attention due to their unique catalytic properties and high metal utilization. In these catalysts, precise control over both the metal and ceria speciation was found to be key for optimizing catalytic performance. Although substantial progress has been made in identifying catalytically active species and establishing structure-performance relationships, most studies rely on CO oxidation as a model reaction. This work extended this approach by investigating the behavior of ceria-based model three-way catalysts under more realistic operating conditions. These conditions include complex exhaust gas mixtures, fluctuating gas compositions and high temperatures. Particular emphasis is placed on the dynamic nature of metal speciation, which was studied by operando spectroscopy and transient kinetics. Our results reveal that significantly more complex behaviors emerge under realistic conditions than in simplified model reactions. This highlights the critical importance of understanding and controlling dynamic catalyst behavior, as well as identifying the mechanisms of inhibition and deactivation, for the design of effective three-way catalysts. In Chapter 2, Pd-CeO2 and Pt-CeO2 model three-way catalysts containing highly dispersed metal species were investigated under realistic operating conditions. The study included perturbed experiments with oscillating exhaust gas compositions, as well as cold-start tests that mimic the initial phase of rapid catalyst heating. Using quasi-in situ XPS, reducibility was identified as a key parameter determining activity, as it dictates the temperature at which highly active reduced species are formed under reaction conditions.

Open Access

Show Abstract ▼

Abstract: Battery research increasingly relies on advanced imaging, yet open access to such data remains rare, scattered across various sources, and difficult to find. The Battery Imaging Library (BIL) is the first open, curated collection of multi-modal and multi-length scale battery imaging datasets, accompanied by a searchable, FAIR-compliant website. Distinctive features include the release of raw experimental data (radiographs, sinograms, X-ray and electron diffraction patterns) together with rare operando and multi-resolution datasets. Each dataset is linked to Zenodo DOIs with metadata, ensuring persistence and citability; open-source Python scripts for preprocessing and reconstruction are also provided for various CT modalities. BIL enables algorithm benchmarking, machine learning, and teaching using experimental and industrially relevant data. By combining coverage across modalities, length scales, and chemistries with raw data accessibility and a FAIR-aligned web platform, the Battery Imaging Library provides a foundation for openness and reproducibility in battery imaging. The library is available here: https://www.batteryimaginglibrary.com

Open Access

Show Abstract ▼

Abstract: Sluggish kinetics of redox reactions and slow ion transport restrict the performance of lithium-sulfur (Li─S) batteries. Here, we fabricate cathodes containing vertically aligned porous structures hosting atomically dispersed Fe─N4 single-atom catalyst (SAC) sites on graphitic carbon nitride (g-C3N4). Density functional theory (DFT) calculations suggest that the Fe─N4 sites strengthen Li2S adsorption, optimize electronic structure, and lower the reaction energy change associated with liquid-solid transition and Li2S oxidation. Experimental results demonstrate that the atomically dispersed Fe─N4 sites in the vertically aligned porous cathodes made by directional ice templating (DIT) accelerate Li+ ion transport and enable high sulfur loading while exposing abundant catalytic centers, resulting in strong polysulfide affinity, promoted nucleation and decomposition of Li2S bidirectional redox catalysis, and suppressed polysulfide shuttle effect. Benefiting from this structural-catalytic synergy, the cathode delivers a high capacity of 1299.2 mAh g−1 at 0.1 C, and the capacity is retained at 505.9 mAh g−1 after 1 000 cycles at 0.5 C, with a low capacity decay rate of ∼0.042% per cycle. This study highlights a scalable strategy to integrate SAC with vertically aligned porous electrode architecture that promotes fast kinetics of sulfur redox in both directions and mass transport for Li─S batteries.