Silvia Mauri

FexGeTe2 (x = 3; 5) are van der Waals magnets which, under the right conditions, can attain above-room-temperature Curie temperatures (TC). Owing to their high TC, their persistent spin order holds potential for a myriad of nanodevice applications both at and beyond room temperature. While the applications of thin films of these metallic two-dimensional ferromagnets have been explored in depth, use of their nanoparticles as catalysts for applications in green chemistry remains an untapped territory. Here, recent experimental investigations providing insights into the catalytic behavior of FexGeTe2 are discussed. Furthermore, employing in operando synchrotron-based X-ray radiation techniques in order to detect spectroscopic fingerprints of magnetic ordering in nanoparticles of FexGeTe2 is also proposed as a unique tool to gain fundamental insights into the role of their spin polarization in the catalytic process. This perspective is expected to endorse future research on the use of FexGeTe2 as magneto-catalysts for green chemistry.

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 M₅ and Cu L₃ 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.

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.

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.

A-site doped SrTiO₃ is considered as a promising substitute for traditional anodic metals in solid oxide fuel cells (SOFCs). In this study, we present the reactivity of La_0.2Sr_0.25Ca_0.45TiO₃ (LCSTO), La_0.2Sr_0.7TiO₃ (LSTO), and SrTiO₃ (STO) toward H₂ by operando ambient pressure NEXAFS spectroscopy and theoretical spectra simulation with FDMNES code. The samples were synthesized by MBE (molecular beam epitaxy), hydrothermal, and modified-Pechini routes. We found that the reducibility of the samples depends not only on their stoichiometry but also on the morphology, which is determined by the synthetic method. The results of these experiments give insight into the reducibility of Ti⁴⁺ in perovskites as well as the opportunity to further optimize the synthesis of these materials to obtain the best performance for SOFC applications.

We employed operando soft X-ray absorption spectroscopy (XAS) to monitor the changes in the valence states and spin properties of LaMn_1-x Co _x O₃ catalysts subjected to a mixture of CO and O₂ at ambient pressure. Guided by simulations based on charge transfer multiplet theory, we quantitatively analyze the Mn and Co 2p XAS as well as the oxygen K-edge XAS spectra during the reaction process. The Mn sites are particularly sensitive to the catalytic reaction, displaying dynamics in their oxidation state. When Co doping is introduced (x ≤ 0.5), Mn oxidizes from Mn²⁺ to Mn³⁺ and Mn⁴⁺, while Co largely maintains a valence state of Co²⁺. In the case of LaCoO₃, we identify high-spin and low-spin Co³⁺ species combined with Co²⁺. Our investigation underscores the importance to consider the spin and valence states of catalyst materials under operando conditions.