Faraday Discussions最新文献

{"title":"Evolution of size-selected Pt cluster catalysts on prototypical oxide supports.","authors":"Lorenz J Falling, Maximilian Huber, Johanna Reich, Matthias Krinninger, Sebastian Kaiser, Markus Döblinger, Marian D Rötzer, Maximilian Krause, Andrey Shavorskiy, Suyun Zhu, Ueli Heiz, Hendrik Bluhm, Friedrich Esch, Barbara A J Lechner","doi":"10.1039/d6fd00002a","DOIUrl":"10.1039/d6fd00002a","url":null,"abstract":"<p><p>The current quest for new pathways into sustainable, efficient and durable energy conversion technologies makes the used for a fundamental understanding of the atomic-scale phenomena underlying catalytic processes ever more pressing. In this context, characterizing catalyst particles <i>in situ</i> provides valuable information about the evolution of their composition, structure, oxidation state and charge state during an ongoing process. To disentangle the influence of individual parameters - temperature, pressure, gas composition, cluster size, as well as support acidity, redox state and defect density - it is crucial to control them precisely and separately in experiments. At the example of size-selected Pt_<i>n</i> clusters - <i>i.e.</i> sub-nm particles defined to the exact number of atoms - on flat oxide supports, we follow their rich evolution phenomena <i>via</i> (synchrotron-based) X-ray photoelectron spectroscopy (XPS) and scanning tunnelling microscopy (STM) during temperature ramps and in various gas environments. Here, we present our experience with these highly defined, yet complicated-to-create samples in ultra-high vacuum (UHV) and at mbar pressures. We discuss their stability during transport to synchrotrons and under reaction conditions on three prototypical oxide supports and show the various phenomena that can be disentangled. Pt_<i>n</i> clusters on the non-reducible silicon dioxide, SiO₂, remain size-selected and show remarkable stability. Doping strongly influences the size-dependent binding energy shifts and changes the Pt response to oxidative and reaction conditions, which we attribute to different cluster geometries: p-type doping leads to wetting, enhanced sinter resistance and a diminished response to oxidative environments, compared to clusters on n-type doped samples. We compare the system with our previous findings of a similar change in dimensionality for Pt₂₀ clusters on the reducible ceria, CeO₂(111), support, induced by modulation of its O vacancy density. The Pt_<i>n</i>/CeO₂ system is particularly interesting for strategies to stabilize and redisperse Pt clusters dynamically. Finally, we study the evolution of Pt_<i>n</i> clusters on another reducible oxide support, magnetite, Fe₃O₄(001), in 0.1 mbar alternating redox conditions at RT and elevated temperature. In analogy to findings previously reported for Pt/TiO₂(110), the clusters either become encapsulated by a thin oxide film <i>via</i> strong metal-support interaction (SMSI) or deeply buried in the magnetite. Overall, our approach of following the evolution of size-selected clusters on oxide supports leads to fundamental atomic-scale insights on nano-scale catalyst materials, on our path to sustainable, dynamic and self-repairing catalysts.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"567-590"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13196843/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148004267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Developing the science of self-healing catalysts.","authors":"Abhaya K Datye, Hien Pham, Andrew DeLaRiva, Brandon Burnside, Yipeng Sun, Andeas Sundermann, Yong Wang","doi":"10.1039/d5fd00154d","DOIUrl":"10.1039/d5fd00154d","url":null,"abstract":"<p><p>It is the dream of every catalyst designer to design catalysts that continue to operate without loss of performance. However, heterogeneous catalysts are susceptible to loss of performance due to sintering, the loss of physical surface area and the growth of nanoparticles, especially catalysts that operate at elevated temperatures. To restore catalyst activity, a regeneration step is needed. This is possible in petroleum refining or alkane dehydrogenation where the reactor or the catalyst must be taken offline for regeneration. But this is not possible for emission-control catalysts, which must operate in the honeycomb monolith for the full useful life of the vehicle. Here, we elucidate the design features that allow emission-control catalysts to mitigate the loss of activity under normal operating conditions. We seek to determine why certain metal/support combinations perform better than others. In this study, we subjected catalysts to accelerated aging protocols, which are used in industry to screen catalyst formulations. For diesel oxidation catalysts, this involves heating under oxidizing conditions with steam at 800 °C. For three-way catalysts, the aging is performed in the presence of steam at 980 °C or higher, under cyclic reducing and oxidizing conditions. At these aging temperatures, the primary mechanism of sintering involves Ostwald ripening, where mobile species, typically single atoms or oxides or hydroxides, diffuse over the surface or are transported through the vapor phase and condense to form larger particles, leading to loss of activity. To allow these catalysts to continue to operate indefinitely, without requiring regeneration, the catalyst must provide opportunities to trap the atoms and then to reconstitute the active sites. Three-way catalysts operate under oscillatory conditions, providing opportunities for self-healing that are not available in diesel oxidation catalysts, which operate under lean conditions (excess oxygen). Unravelling the principles that lead to self-healing behaviour in both these application areas yields insights that can guide design of robust heterogeneous catalysts.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"591-604"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147939039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of adsorbate induced surface strain on oxygen island formation on platinum surfaces.","authors":"Florian Nitz, Alexander Kandratsenka, Daniel J Auerbach, Theofanis N Kitsopoulos, Alec M Wodtke","doi":"10.1039/d5fd00161g","DOIUrl":"10.1039/d5fd00161g","url":null,"abstract":"<p><p>The reactivity of heterogeneous catalysts under working conditions may be strongly influenced by adsorbate-adsorbate interactions which alter reaction barriers and lead to the formation of ordered adsorbate structures like islands. To predict catalytic reactivity, accurate knowledge of adsorbate-adsorbate interaction energies is required, but it is rarely available. One challenge arises from the surprisingly long range over which these interactions exert influence. We show in this work-using DFT with periodic boundary conditions and an (8 × 8) unit cell-that a single O-atom adsorbed at Pt(111) induces significant Pt atom displacements out to more than 7 Å. This adsorbate induced surface strain allows O*-atoms at distances of 14 Å to experience repulsion between one another due to the adsorbate induced displacement of the Pt atoms between them. Similar calculations using smaller unit cells overestimate repulsion due to interactions between O* atoms in neighboring periodic images. The use of an (8 × 8) unit cell removes this error, revealing short range attractive interactions between 3rd nearest neighbors. We have used these improved DFT interaction energies to perform kinetic Monte Carlo simulations of oxygen island formation and to show how the interplay of short- and long-range forces determines the sizes and shapes of these islands. Neglect of long-range interactions leads to round and compact island structures, which are in conflict with STM experiments. Including all interactions out to the 9th nearest-neighbor results in simulations that eerily resemble the STM observations.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"157-171"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13126644/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147808565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interpretable Bayesian optimization for catalyst discovery.","authors":"Akhil S Nair, Lucas Foppa, Matthias Scheffler","doi":"10.1039/d5fd00159e","DOIUrl":"10.1039/d5fd00159e","url":null,"abstract":"<p><p>Bayesian optimization (BO) efficiently explores vast design spaces using probabilistic surrogate models, enabling the guided discovery of materials with desired properties. However, most BO frameworks rely on the knowledge of a few key physical parameters (features) correlated with the materials property of interest. This is a challenge in heterogeneous catalysis, where the material properties are governed by an intricate interplay of multiple physical processes, and the mentioned parameters are typically unknown. Here, we introduce the Sparse Adaptive Representation-based Bayesian Optimization (SARBO) framework that utilizes the sure independence screening and sparsifying operator (SISSO) symbolic-regression method for on-the-fly selection of key physical parameters correlated with materials properties during BO. Crucially, SISSO takes into account nonlinear relationships and interactions between multiple parameters when selecting key features. We demonstrate that SARBO enables efficient navigation of the materials spaces and outperforms widely used feature-selection approaches for the simulated discovery of single- and dual-atom alloy surface sites capable of activating CO₂, a critical step in the CO₂ reduction reaction.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"298-311"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13127247/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147808822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rethinking catalysis: interpretable AI and description of real-world conditions <i>via</i> materials genes.","authors":"Lucas Foppa, Matthias Scheffler","doi":"10.1039/d5fd00137d","DOIUrl":"10.1039/d5fd00137d","url":null,"abstract":"<p><p>Descriptors link basic physicochemical parameters that characterize the materials and the environment to the catalytic performance. Traditionally, descriptors are rooted in mechanistic understanding of elementary surface reactions gained from surface science and atomistic simulations on well-defined surfaces and under vacuum. However, real-world catalysis operates under elevated pressures and temperatures, where an intricate interplay of multiple physical processes, including significant materials' restructuring and transport phenomena, governs performance. To bridge this gap, we introduced an interpretable artificial intelligence (AI) approach that identifies key physicochemical parameters correlated with the measured catalytic performance. Analogous to genes in biology and medicine, these \"materials genes\" provide a statistical description of catalysis without requiring the explicit atomistic description of the underlying physical processes. Here, we combine the sure-independence-screening-and-sparsifying-operator (SISSO) symbolic-regression AI approach with a sensitivity analysis based on partial derivatives to determine the most influential genes needed to describe the selectivity of supported palladium-based metal alloy nanoparticles in the hydrogenation of concentrated acetylene streams. The identified genes include the calculated average d-band center and the measured average particle diameter, indicating the crucial role of adsorption and structure sensitivity on the formation of ethylene.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"257-277"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13151911/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147865954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"What can Raman spectroscopy really say about the adsorbed CO on roughened Cu electrodes in CO₂ electroreduction conditions?","authors":"Yu Wei, Anastassia N Alexandrova","doi":"10.1039/d5fd00119f","DOIUrl":"10.1039/d5fd00119f","url":null,"abstract":"<p><p>Electrochemical CO₂ reduction (CO₂RR) offers a promising strategy to recycle carbon by converting CO₂ into valuable fuels and chemicals. So far, Cu-based catalysts remain the most effective for producing high-value multi-carbon products from CO₂. Under the operating conditions of the CO₂RR, Cu is known to undergo significant surface reconstruction. Furthermore, this reconstruction is crucial for creating the active sites for the CO₂RR, whereas flat surfaces catalyze only the hydrogen evolution reaction (HER). This poses challenges for accurately elucidating the structure-activity relationship. To address this, recent research has employed CO as a probe molecule, and combined <i>in situ</i> surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) to reveal how surface reconstruction affects not only the macroscopic morphology but also the local active sites, adsorption of key intermediates, and the overall catalytic performance. A specific metric tracked in SERS studies is the intensity ratio of the Cu-CO stretching band to the CO rotational band, as it is believed to be related to the CO coverage. Here, we challenge this assumption. We combine grand canonical genetic algorithm (GCGA) global optimization with grand canonical density functional theory (GCDFT) calculations to find optimal accessible CO coverages under CO₂RR conditions. Then, we use these structures to investigate how different surface roughness, facets, and CO adsorption sites influence the Raman spectra, and the intensity ratio of interest. We show that the changes in the Raman intensity ratio are not solely determined by CO coverage. The adsorption site has a significant influence on the spectral signature, while the realistic reconstruction of the Cu surface impacts the available sites in a potential-dependent manner. The local environment of the adsorbed CO, including the site, coverage, and secondary coordination sphere, affect the stretching and rotation mode frequencies and intensities. We conclude that the SERS signature, while it can be exceptionally useful, alone is insufficient to establish a rigorous, quantitative correlation between the surface coverage or density of species and the production rates of target products required for a clear structure-activity relationship.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"46-60"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147757580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The ever-evolving active site: transformation of single atoms to extended structures during the Rh-catalyzed reverse water-gas shift reaction.","authors":"Greg Barber, Xiaobo Chen, Anastassiya Khan, Jake Heinlein, Sabrina M Gericke, Meng Li, Dmitri Zakharov, Judith Yang, Ashley R Head, Matteo Cargnello, Robert M Rioux, Simon R Bare","doi":"10.1039/d5fd00172b","DOIUrl":"10.1039/d5fd00172b","url":null,"abstract":"<p><p>At low temperatures (<400 °C), single atoms of Rh supported on rutile TiO₂ (rTiO₂) are responsible for the formation of CO during the reverse water gas shift (RWGS), while methane production is associated with the Rh-TiO₂ interface due to the observed correlation between methane formation rates and the volume-averaged Rh nanoparticle diameter. As the temperature is increased to >540 °C, there is a notable increase in CO selectivity as the methane production rates tend towards zero. The time to reach zero depends on the temperature but is independent of the initial Rh structure (single atoms and/or nanoparticles), which is controlled by the catalyst preparation method (wetness impregnation <i>versus</i> colloidal nanoparticles). At 600 °C and >4 h time on stream, the catalytic behaviour becomes completely agnostic to the initial Rh structure as well as weight loading, and the catalysts are highly selective for the RWGS reaction. Post-reaction HR-TEM image analysis confirms Rh nanoparticles crystallize/order during the reaction; at 400 °C, most of the Rh particles are disordered, while at 600 °C, they are more ordered (<i>i.e.</i>, there is the development of defined faceting). Infrared spectroscopy of CO adsorption on Rh nanoparticles confirms the appearance of defined facets after annealing in nitrogen at high temperatures. Annealing the Rh/rTiO₂ catalysts prior to the RWGS reaction demonstrates the structural transformation of Rh depends only on time and temperature and not on reactant or product fugacity. Sites responsible for stabilizing Rh single atoms are no longer competent at higher temperatures, enabling single atom integration into existent nanoparticles. As the reaction temperature is increased to temperatures >540 °C, the dominant Rh structure for CO production evolves from single atoms to extended surfaces.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"495-520"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147808579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon dioxide hydrogenation on copper and nickel catalysts <i>via</i> a conformal sampling approach.","authors":"Thantip Roongcharoen, Alessandro Fortunelli","doi":"10.1039/d5fd00132c","DOIUrl":"10.1039/d5fd00132c","url":null,"abstract":"<p><p>We present a computational workflow, the Conformal Sampling of Catalytic Processes (CSCP) approach, and its application to the case of heterogeneous hydrogenation/reduction of carbon dioxide (CO₂) on copper and nickel catalysts. CO₂ activation is of critical importance for a sustainable global future and one of the major reactions for which sustainable routes must be found urgently. We use the fcc(100) facet of Cu as a worked-out case, and exhaustively derive at the DFT level its reaction mechanisms. We then apply CSCP to first derive a Machine Learning Interatomic Potential (MLIP) for this initial system, and then carry over the knowledge derived on Cu(100) to a pure monometallic facet, Ni(100), to rapidly derive a MLIP for this different system, so as to test the transferability of the approach. The accuracy of the so-derived MLIPs is excellent, predicting both reaction energies and energy barriers for all the mechanistic steps of this complex reaction diagram with consistent and uniform accuracy, with a maximum discrepancy of 0.05 eV for Cu and 0.03 eV for Ni. In the exception cases in which this discrepancy is larger, we show and rationalize that this is due to a change in the reaction mechanism, where the MLIP simulations explore pathways different from the reference DFT ones, without however prejudicing their absolute accuracy. The CSCP-MLIPs are thus shown to be able to assure a transferability <i>en par</i> with the best physics-based models, provide alternative atomistic mechanisms of catalytic processes, and offer themselves as a tool for catalyst rational design on a process societally relevant and exhibiting significant catalytic complexity.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"312-335"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147757671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ionic liquid overlayers stabilize ligand-coordinated oxide-supported single-atom Pd heterogeneous catalysts for partial hydrogenation of acetylene.","authors":"Ayanna M Culmer-Gilbert, Steven L Tait","doi":"10.1039/d5fd00164a","DOIUrl":"10.1039/d5fd00164a","url":null,"abstract":"<p><p>Single atom catalysts offer promising mechanisms for highly selective hydrocarbon conversions in heterogeneous catalysts that can be scaled up to address industrially-relevant challenges. Stability of the catalysts is critical, not just because of the need to maintain high conversion for long time periods, but also to maintain the precise single-atom environment that facilitates high reaction selectivity. We have demonstrated a ligand-coordination strategy for oxide-supported single atom Pd catalysts and, in this work, we demonstrate that ultrathin ionic liquid overlayers add significant stability to the catalysts. These catalysts can be synthesized with single-atom character at loadings as high as 0.8 wt% Pd and are effective for selective partial hydrogenation of acetylene to ethylene, as demonstrated by flow reactor experiments. The addition of the ionic liquid overlayer enables a wider operational range of temperature and provides increased resistance against sintering. The ionic liquids do not hinder the C₂ molecule access to the Pd active sites, but they do enable improved reaction selectivity. The dynamic interface of ionic liquid and cerium oxide provides an outstanding environment for Pd coordination to small organic ligands that define a highly effective Pd(II) species for selective hydrogenation.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"605-619"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148519577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Operando</i> XPS studies of precisely size-selected Pd nano-catalysts for methane oxidation.","authors":"Alexander I Large, Henry Hoddinott, Haamidah Sana, Elizabeth Jones, James J C Counter, Matthijs A van Spronsen, Santosh Kumar, David C Grinter, Pilar Ferrer, Bernd von Issendorf, Richard E Palmer, Georg Held","doi":"10.1039/d5fd00171d","DOIUrl":"10.1039/d5fd00171d","url":null,"abstract":"<p><p>The importance of cluster-size effects in heterogeneous catalysis is now well recognized. X-ray photoelectron spectroscopy (XPS) is an obvious technique to study size-dependent changes in the chemical composition and electronic structure of catalyst nanoparticles. However, as XPS is an averaging technique based on the detection of electrons, experiments require a narrow distribution of cluster size and a conducting homogeneous support in order to avoid sample charging, which would prevent accurate measurements of chemical shifts. Traditional methods of catalyst synthesis by impregnation/calcination of support powders lead to very large particle size distributions (typically ±50%) and insulating samples. They therefore fail both of the above criteria and make it extremely difficult to extract precise sample characterisation. Here we present an alternative approach designed to enable XPS analysis in vacuum and under reaction conditions, whereby: (i) nanoparticles are synthesized by gas condensation and passed through a mass filter, which allows size selection in the range of 1 to 10 000 atoms with typically ±4% accuracy; (ii) these particles are deposited onto a thin Al₂O₃ film grown on Al foil, which mimics the properties of conventional alumina supports while being conductive enough to avoid any charging-related artefacts in the XPS spectra. In vacuum, size-dependent Pd 3d binding-energy shifts up to 1.65 eV were recorded for supported Pd nanoparticles. Changes in the chemical composition of Pd nanoparticles were studied by near-ambient pressure (NAP)-XPS under dry and wet reaction conditions for methane oxidation (CH₄ + O₂ [+H₂O]) in the temperature range between 150 °C and 450 °C. Under dry reaction conditions large Pd particles appeared to oxidise almost fully to Pd(II), whereas smaller clusters showed a mix of Pd(0) and Pd(II) oxidation states. Under wet conditions, oxidation starts at lower temperatures and particles of all sizes were fully oxidised when the highest temperature was reached. Sintering during the temperature ramp cannot be excluded, especially for the smaller particles, and may be part of the reason for the different behaviour under wet conditions. This study clearly shows composition changes which are particle-size dependent and demonstrates the possibilities of fine-tuning catalytic activity if better size-control can be achieved in catalyst synthesis.</p>","PeriodicalId":76,"journal":{"name":"Faraday Discussions","volume":" ","pages":"521-538"},"PeriodicalIF":3.1,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13576673/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147939079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}