Perovskite oxides are a versatile class of materials with tunable electronic structures, making them attractive for catalytic applications, including the oxygen evolution reaction (OER). The surface reactivity of these oxides is closely tied to the electronic structure of transition metal cations, particularly their 3d orbital occupation, which can be modulated by interfacial engineering. In this work, we investigate how subsurface engineering influences the interaction of ultrathin LaCoO3 films with water vapor. Using (near) ambient pressure core-level spectroscopy, we observe distinct differences in hydroxyl affinity and Co valence response depending on the electronic structure imposed by the underlying layer. Ultrathin LaCoO3 films with a higher initial Co oxidation state show stronger hydroxyl affinity, while those with a lower Co valence show more significant electronic changes upon water exposure. Our findings demonstrate a form of "remote control" in surface chemistry, where subsurface electronic engineering dictates hydroxyl affinity and electronic response at the surface. This concept offers a new degree of freedom to optimize oxide-adsorbate interactions for (electro)catalysis.

In this work, we explored the catalytic decomposition of methanol to syngas at 300 °C using intermetallic Ni3Sn2 nanoparticles (NPs) synthesized via a chemical route. Our study employed a comprehensive approach combining operando Ambient Pressure soft X-ray absorption spectroscopy with a suite of ex situ techniquesincluding X-ray diffraction, X-ray photoelectron spectroscopy, electron microscopy, and Mössbauer spectroscopyand density functional theory (DFT) calculations. Consistent with the behavior observed in Ni3Sn2 single crystals, we found that the Ni-Sn bonds stabilize the unique electronic structure of the intermetallic Ni active sites, even under strongly oxidizing conditions. Additionally, the nanoparticles exhibit a distinctive morphology characterized by a SnO x -rich protective shell, which further enhances the stability of the Ni sites. These stabilized sites enable the selective decomposition of CH3OH into H2 and CO while effectively suppressing coke formation, a major limitation of conventional metallic Ni catalysts, which are currently a benchmark for this reaction. Our findings suggest a promising strategy for the design of scalable, stable, and cost-effective Ni-based catalysts, unlocking the full potential of methanol as a liquid, portable hydrogen carrier.

Ni 2+ single atoms on PHI photocatalyze the selective semi-hydrogenation of alkynes, using water as the proton source.

Using light and water vapor to reduce CO2 into various carbon-based products, such as methane, is a promising strategy to achieve the conversion of CO2 into useful products. Copper (Cu) is a well-studied photocatalyst due to its high affinity for carbon intermediates, favoring the CO2 evolution reaction (CER) over the hydrogen evolution reaction (HER). Recently, we have shown that adding CuO nanoparticles to light-sensitive materials such as BaTiO3 (BTO) and TiO2 enhances the photocatalytic performance of the materials. Therefore, to elucidate the interaction between CuO nanoparticles and support materials, we combined the results of standard (scanning electron microscopy, X-ray photoemission spectroscopy) and advanced characterization techniques, namely, operando ambient-pressure near-edge X-ray absorption fine structure (NEXAFS) and in situ Fourier transform infrared (FTIR) spectroscopies, for investigating the photocatalytic reaction mechanism of CuO-BTO and CuO-TiO2 photocatalysts in operando CO2 photoreduction conditions. Our results confirmed enhanced methanation on the CuO-BTO system over a TiO2-based catalyst: NEXAFS analysis allowed to establish that the activity of both catalysts is linked to the formation of a reversible redox couple Cu+/Cu2+ and that the CuO-BTO interface can promote a more efficient charge separation; the electron trapping on Ti centers was directly observed on Ti NEXAFS spectra, evidencing a strong charge recombination suppression, which can favor CO2 reduction. IR revealed that CO2 is strongly activated on the CuO-BTO surface, forming carbonates that are converted to CH4 through the formation of formates as intermediates.

Antonio Cosimo Pio Trimboli is a PhD candidate at the Università di Reggio Calabria (UniRC), where he works on the catalytic upcycling of polyolefins. Emilia Paone is an assistant professor at UniRC, where she develops green catalytic processes for converting waste into valuable products. Piero Torelli is a senior researcher at the Istituto Officina dei Materiali (CNR-IOM), where he uses synchrotron-based spectroscopies to study catalytic materials and surface chemistry. Elena Groppo is an associate professor at the University of Turin, where she focuses on the structural and spectroscopic characterization of catalysts and functional materials. Francesco Mauriello is an associate professor at UniRC and an expert in the catalytic upgrading of biomass and waste.

Ni/CeO2 catalysts for dry reforming of methane (DRM) were prepared via a medium energy, solvent-free mechanochemical route by ball milling ceria with Ni precursors (nitrate or chloride salts). The effect of precursor type and milling time on surface area, structure, and redox properties was assessed by N2-physisorption technique (BET), X-ray powder diffraction (XRD), and H2-temperature programmed reduction (H2-TPR). Catalytic performance was benchmarked against catalysts prepared by incipient wetness impregnation (IW). Brief milling produced catalysts with higher initial activity and, in selected cases, a more favorable activity-retention behavior than the impregnated reference. Results from a multi-technique analytical approach which combines high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS), indicate that the mechanical action promotes the formation of a distinctive Ni–ceria interfacial nanostructure, whose distribution and accessibility depend on mechanochemical synthesis parameters and correlate with catalytic behavior in DRM.

Understanding the role of intrinsic magnetic order on the oxygen evolution reaction (OER) requires careful consideration of the magnetic properties of both the catalytic surface and bulk under operating conditions. Because these often diverge from those of the pristine material, operando characterization that directly links magnetic behavior to catalytic activity is essential. Here, we investigate the magnetic properties of thin-film OER catalysts using a combination of temperature-dependent operando ferromagnetic resonance spectroscopy (FMR), ambient-pressure X-ray magnetic circular dichroism (XMCD), and operando X-ray absorption spectroscopy (XAS). A direct correlation between changes in long-range magnetic order and OER activity, with minimal changes in the catalyst's electronic state was observed. Non-interacting ferromagnetic regions appear to contribute to enhanced activity at temperatures just above . The enhancement is further amplified when the thin film undergoes the bulk paramagnetic-to-ferromagnetic transition below . Our results suggest that interatomic spin-exchange interactions, occurring within ferromagnetic regions and across the ferromagnetic bulk and between these atoms and adsorbates, dominate the observed OER enhancements, potentially augmented by short-range spin-polarized conduction effects. These findings highlight that local ferromagnetic order, governed by exchange interactions over a few unit-cells, plays a crucial role in modulating surface reaction dynamics, offering mechanistic insight into spin-dependent catalysis.

Artificial multiferroic heterostructures offer a versatile platform for engineering magnetic properties through interfacial strain and magnetoelectric coupling. In this framework, we demonstrate the growth of both Ni and La0.67Sr0.33MnO3 ferromagnetic thin films on KNbO3 (100) single crystals. We show, by combining structural and magneto-optical characterizations, how their magnetic responses are affected by the structural transitions taking place in the substrate as a function of temperature. In particular, we observe sensitive modifications in the ferroelectric domain composition of KNbO3, especially after cooling from orthorhombic to rhombohedral phase, leading to a transition from in-plane anisotropic to isotropic magnetization behaviour in Ni thin films. Temperature dependent magnetic characterizations show a coercivity modulation while crossing the structural transition for both Ni and La0.67Sr0.33MnO3 films, signature of interfacial strain-driven coupling. To the best of our knowledge, these are the first reported KNbO3-based multiferroic heterostructures, establishing this lead-free material as a potential functional host for both metallic magnetostrictive and complex oxide thin films.

The modification of the electronic properties of CeO2 thin films through Cu doping is a promising approach to enhancing their performance in photoinduced water splitting (WS). In this study, undoped and Cu-doped CeO2 films of 5 nm thickness with 5 and 11% Cu atomic concentrations were characterized under ambient pressure conditions by near-edge X-ray absorption fine structure (NEXAFS) to provide insights into the film modification and the water splitting process during exposure to water and to laser light at different temperatures. The analysis of NEXAFS data, acquired at the Ce M-5 and Cu L-3 edges, reveals temperature-dependent changes in the oxidation states of Ce and Cu. Notably, a temperature-dependent evolution of the Ce3+ concentration is observed during water exposure, accompanied by spectral changes consistent with a partial reduction of Cu2+ to Cu1+ in the film with the highest dopant concentration. The ambient-pressure NEXAFS measurements highlight the role of Cu dopant ions in modifying the electronic structure of CeO2 and the catalytic response in the presence of water and illumination, enabling more efficient hydrogen production. In parallel, micro gas chromatography analysis revealed a marked increase in hydrogen production from the 11% Cu-doped CeO2 film compared to the undoped CeO2 and the 5% Cu-doped films. These results provide crucial insights into the structure-function relationship in Cu-doped CeO2, offering pathways to optimize the design of materials for hydrogen production and related applications.

Magnetoelectric materials are one of the potential candidates that can counter the growing need of low‐power memory and spintronic devices due to their ability to electrically control magnetic states. Manipulation of a magnetic state with the sole use of an electric field has faced several challenges like volatility and non‐reproducibility. Here, we propose a magnetostrictive FeGa thin film interfaced with a relaxor ferroelectric substrate (PMN‐PT) having a [011] surface cut. The polarization rotation is controlled near the coercive electric fields and stabilized at remanence, which generates distinct strained states. This strain transfers to the FeGa layer mechanically, inducing a net rotation of magnetization without the need of any bias magnetic field applicators. Imaging of the magnetic domains reveals spatial and real‐time information about its variation and adds insight on the modification of magnetic anisotropy. The newly created magnetic information can be erased by reaching ferroelectric saturation and subsequently regenerated through specific electrical pulses. These results demonstrate the possibility of manipulating the magnetization via controlled polarization rotation, for use in strain‐driven magneto‐electronics.

A central challenge in water electrolysis lies with the oxygen evolution reaction (OER) where the formation of molecular oxygen (O 2 ) is hindered by the constraint of angular momentum conservation. While the reactants OH − or H 2 O are diamagnetic (DM), the O 2 product has a paramagnetic (PM) triplet ground state, requiring a change in spin configuration when being formed. This constraint has prompted interest in spin‐selective catalysts as a means to facilitate OER. In this context, the roles of magnetism and chirality‐induced spin selectivity (CISS) in promoting the OER reaction have recently been investigated through both theoretical and experimental studies. However, pinpointing the key principles and their relative contribution in mediating spin‐enhancement remains a significant challenge. This roadmap offers a forward‐looking perspective on current experimental trends and theoretical developments in spin‐enhanced OER electrocatalysis and outlines strategic directions for integrating incisive experiments and operando approaches with computational modeling to disentangle key mechanisms. By providing a conceptual framework and identifying critical knowledge gaps, this perspective aims to guide researchers toward dedicated experimental and computational studies that will deepen the understanding of spin‐induced OER enhancement and accelerate the development of next‐generation catalysts.

The perovskite ABO3 structure serves as the foundation for diverse functional and quantum materials, yet its applications are hindered by challenges in control of film stoichiometry and the precise construction of interfaces, particularly compared to conventional semiconductors. While a layer-by-layer growth mode is frequently cited, we demonstrate that many transition-metal perovskite oxides self-assemble via an energetically favorable layer-inversion mechanism. This phenomenon can be strategically exploited to fine-tune stoichiometry and surface termination at any point during growth. Layer inversion produces consistent behavior in electron diffraction rocking curves and diffracted-beam intensity oscillations during alternating A- and B-site shuttered growth across various polar and nonpolar surfaces. We introduce a model that accurately interprets these oscillations, enabling an entirely in situ method for precise relative and absolute calibration of multielemental A- and B-site fluxes at the percent level. This approach is successfully applied to the growth of a single-phase high-entropy oxide film.

Synthesis of substituted anilines upon nucleophilic addition of secondary amines to cyclohexanone derivatives followed by aromatization of the enamine by employing a combination of Ir-polypyridine complex as a photoredox catalyst and cobaloxime as H2-evolution catalyst is developed recently by Leonori et al. In this work, the homogeneous photoredox catalyst is replaced by a heterogeneous and metal-free mesoporous graphitic carbon nitride (mpg-CN). Substituted aromatic amine and H2 are formed simultaneously. Combination of X-ray spectroscopies reveals charge transfer from cobaloxime to mpg-CN in the dark. Illumination of the catalytic system with visible light induces electron transfer from mpg-CN to cobaloxime and formation of persistent Co(II) species. The results of density functional theory modeling suggest that the studied reaction is strongly endothermic and endergonic. Thus, energy of photons is stored in the reaction products-H2 and the aromatic amine.

Metal-organic frameworks (MOFs) are receiving growing interest as transformative materials for real-world atmospheric water harvesting applications. However, obtaining molecular-level details on how surface effects regulate MOF water uptake has proven to be elusive. Here, we present a novel methodology based on ambient pressure soft X-ray absorption spectroscopy (AP-NEXAFS), machine learning-assisted theoretical spectroscopy and molecular dynamics simulations to gain selective insights into the behaviour of water at a MOF crystal surface. We applied our interdisciplinary method to investigate the structural and dynamical properties of water at the surface of the Mg-MOF-74 system, while obtaining complementary information on the water uptake and release from the bulk by synchrotron powder X-ray diffraction. Our investigation pointed out the simultaneous presence of Mg open sites and residual gas-phase water during dehydration, and proved that during water release a high number of surface Mg sites still interact with one or two water molecules. Conversely, when looking at the bulk, a significantly lower number of Mg sites have been found to interact with water molecules in the same experimental conditions. This behaviour suggests that the water adsorption (desorption) process starts from the interior of the material and propagates towards the channel openings. The combined approach based on AP-NEXAFS, PXRD experimental determinations and ML-supported theoretical analyses has been found to be a valuable tool to provide a thorough description of the water harvesting process at both surface and bulk of the crystal.

In the growing field of low-cost electronics, the epitaxy of complex oxide thin films on a Si substrate requires significant technical means. Therefore, a large attention is paid to the release of a freestanding oxide of interest from its deposition support which is then placed onto a low-cost substrate, via the etching of an intermediate sacrificial layer. The use of a sacrificial layer offers several advantages since the flexible polymer exploited for the transfer can also be fully utilized to design a flexible heterostructure. For green technology, more and more research investigations are being undertaken on these sacrificial layers etched by water. While Sr3Al2O6 and SrVO3 are archetypical examples, the need to find new materials with different lattice parameters and symmetry is critical to reach the epitaxy of numerous materials of interest. In this study, the possibilities of an A-site cationic variation in AVO3 with A = Sr and/or Ca thin films are highlighted to expand the water-soluble material's family reaching the smallest lattice parameter ever presented up to now. In addition to bring various compounds with different ageing properties to the literature, optical spectrophotometry operando characterizations to follow the chemical etching of the sacrificial layers in real-time are exploited.

In the growing field of spintronic devices incorporating antiferromagnetic materials, control of the domain configuration and Néel axis orientation is critical for technological implementations. Here we show by X-ray magnetic linear dichroism in photoelectron emission microscopy how antiferromagnetic properties of LaFeO3 (LFO) thin films can be tailored through epitaxial strain. LFO films were grown via molecular beam epitaxy with precise stoichiometric control, using substrates that span a range of strain states—from compressive to tensile—and crystal symmetries, including different crystallographic orientations. First, we show that epitaxial strain dictates the Néel axis orientation, shifting it from completely in-plane under compressive strain to completely out-of-plane under tensile strain, regardless of the substrate crystal symmetry. Second, we find that LFO films grown on cubic substrates exhibit a fourfold distribution of antiferromagnetic domains, but can be controlled by varying the substrate miscut, while those on orthorhombic substrates, regardless of strain state, form large-scale monodomains, a highly desirable feature for spintronic applications. Precise control over antiferromagnetic domain configurations and Néel axis orientation is essential for technological advancement of spintronic devices. Here, the authors use epitaxial strain to tailor the magnetic properties of LaFeO3 thin films, demonstrating a crystal engineering approach which may have much wider applicability.

We report the room temperature, low-voltage-enabled modulation of the optical response of hybrid transparent-conductive-oxide/ferroelectric multilayers. We have fabricated an optical multilayer consisting of Al-doped ZnO (AZO) and BaTiO3 films deposited on a Nb-doped SrTiO3(110) substrate. Applying a low voltage between the AZO film and the substrate, a significant variation of the system's optical response has been detected by means of in operando spectroscopic ellipsometry. The voltage-induced variations have been ascribed to a combination of charge accumulation/depletion at the insulator/semiconductor interface and the field-induced Pockels effect in the BaTiO3 layer and successfully reproduced by an optical model including these effects. We have deduced a variation of the refractive index in AZO in the infrared range by more than 0.1 at an applied bias of 0.2 V and by more than 2 at an applied bias of just 3 V at room temperature, which can be strongly appealing for voltage-modulated active optical systems.