Physical and Theoretical Chemistry, Condensed Matter Physics, Spectroscopy, Surfaces and Interfaces
13
Scopus Publications
100
Scholar Citations
6
Scholar h-index
5
Scholar i10-index
Scopus Publications
Unraveling Nanoarchitectonics-Driven Metal–Support Interactions and Size Effects Governing CO Oxidation Activity of Size-Selected Pt Clusters on TiO2 and SnO2 Supports Stanislav Valtera, Mykhailo Vaidulych, Federico Loi, Kevin Oldenburg, Ingo Barke, et al. Small Structures, 2026 Supported size‐selected clusters represent a unique class of materials offering high tunability of the chemical properties with high efficiency of material utilization. Herein, Pt n ( n = 13, 40) clusters supported on two technologically relevant supports, TiO 2 and SnO 2 , were studied for CO oxidation under atmospheric pressure conditions. The catalytic activity was found to be directly influenced by both cluster size and support material, with Pt 40 /TiO 2 showing the highest activity. In situ near‐ambient‐pressure X‐ray photoelectron spectroscopy (NAP‐XPS) revealed that, in general, a higher metallicity of the clusters promotes catalytic activity. However, the final oxidation state of Pt does not solely determine the activity, which rather evolves from a combination of factors, including strong metal–support interactions (SMSI) and size‐dependent effects. Ex situ XPS and ion scattering spectroscopy (ISS) measurements on used catalysts highlighted the role of SMSI, particularly in the case of SnO 2 , where SnO 2 overgrowth was suggested to enhance chemical stability and sintering resistance, as witnessed by stability tests conducted using NAP‐XPS. However, this overgrowth also limited access to active Pt sites, reducing CO adsorption and O 2 activation, ultimately leading to lower catalytic activity of Pt n /SnO 2 compared to TiO 2 ‐supported catalysts.
Limitations in Determining Oxidation States in Condensed Matter at the Subnanometric Scale Deborah Perco, Monica Pozzo, Andrea Berti, Federico Loi, Paolo Lacovig, et al. Journal of the American Chemical Society, 2025 The oxidation state is a fundamental chemical concept commonly employed to rationalize, classify, and predict the chemical reactivity of a variety of compounds. Understanding and defining the elemental oxidation state of solid materials at the atomic level becomes increasingly complex as their physical dimensions are reduced from tens of nanometers─where properties are still dominated by bulk or outer atomic crystal plane characteristics, to the subnanometric limit. In this work, we highlight the significant limitations in determining even a basic quantity, such as the oxidation state, when oxidized low-nuclearity mass-selected clusters are investigated by means of X-ray photoelectron spectroscopy (XPS), widely recognized as the elective approach to resolve different oxidations states. The lack of crystalline order in these nanoclusters, unlike that in periodic bulk systems and in solid surfaces, leads to a broad distribution of measured core levels, as shown in the case study of W nanoclusters. These cannot be unambiguously assigned to a valence state based solely on the knowledge of bulk matter behavior but need close comparison with specific theoretical modeling. Our results emphasize the substantial challenges inherent in understanding the unique properties of nanoscale materials, particularly in making a rigorous and quantitative determination of a fundamental property that takes a relevant role in many chemical processes, and represent crucial knowledge for advancing technologies that rely on the miniaturization of matter in various processes.
Unveiling Inequality of Atoms in Ultrasmall Pt Clusters: Oxygen Adsorption Limited to the Uppermost Atomic Layer Federico Loi, Luca Bignardi, Deborah Perco, Andrea Berti, Paolo Lacovig, et al. Small Structures, 2024 The concept of preferential atomic and molecular adsorption site is of primary relevance in heterogeneous catalysis. In the case of ultrasmall size‐selected clusters, distinguishing the role played by each atom in a reaction is extremely challenging due to their reduced size and peculiar structures. Herein, it is revealed how the inequivalent atoms composing graphene‐supported Pt12 and Pt13 clusters behave differently in the photoinduced dissociation of O2, with only those in the uppermost layer of the clusters being involved in the reaction. In this process, the epitaxial graphene support plays a fundamental active role: its corrugation and pinning induced by the presence of the clusters are crucial for defining the preferential adsorption site on the Pt atomic agglomerates, facilitating the lateral diffusion of physisorbed oxygen at a distance that induces its selective adsorption in the topmost layer of the clusters, and inducing an inhomogeneous charge distribution within the clusters which directly affects the O2 adsorption. The inhomogeneous oxidation of the clusters is resolved by means of synchrotron‐based X‐ray photoelectron spectroscopy and supported by ab initio density functional theory calculations. The possibility to identify the active sites on Pt clusters induced by cluster–support interactions has the potential to enhance the experimentally supported design of nanocatalysts.
The highest oxidation state observed in graphene-supported sub-nanometer iron oxide clusters Deborah Perco, Federico Loi, Luca Bignardi, Luca Sbuelz, Paolo Lacovig, et al. Communications Chemistry, 2023 Size-selected iron oxide nanoclusters are outstanding candidates for technological-oriented applications due to their high efficiency-to-cost ratio. However, despite many theoretical studies, experimental works on their oxidation mechanism are still limited to gas-phase clusters. Herein we investigate the oxidation of graphene-supported size-selected Fen clusters by means of high-resolution X-ray Photoelectron Spectroscopy. We show a dependency of the core electron Fe 2p3/2 binding energy of metallic and oxidized clusters on the cluster size. Binding energies are also linked to chemical reactivity through the asymmetry parameter which is related to electron density of states at the Fermi energy. Upon oxidation, iron atoms in clusters reach the oxidation state Fe(II) and the absence of other oxidation states indicates a Fe-to-O ratio close to 1:1, in agreement with previous theoretical calculations and gas-phase experiments. Such knowledge can provide a basis for a better understanding of the behavior of iron oxide nanoclusters as supported catalysts.
Oxidation at the sub-nanoscale: oxygen adsorption on graphene-supported size-selected Ag clusters Federico Loi, Monica Pozzo, Luca Sbuelz, Luca Bignardi, Paolo Lacovig, et al. Journal of Materials Chemistry A, 2022 Oxidizing size-selected Ag11 clusters on graphene reveals the formation of a bulk-like structure already for few-atom aggregates. The appearance of a bulk AgO crystal structure differs from that observed for metallic clusters of similar size.
Atomic Undercoordination in Ag Islands on Ru(0001) Grown via Size-Selected Cluster Deposition: An Experimental and Theoretical High-Resolution Core-Level Photoemission Study Luca Sbuelz, Federico Loi, Monica Pozzo, Luca Bignardi, Eugenio Nicolini, et al. Journal of Physical Chemistry C, 2021 The possibility of depositing precisely mass-selected Ag clusters (Ag1, Ag3, and Ag7) on Ru(0001) was instrumental in determining the importance of the in-plane coordination number (CN) and allowed us to establish a linear dependence of the Ag 3d5/2 core-level shift on CN. The fast cluster surface diffusion at room temperature, caused by the low interaction between silver and ruthenium, leads to the formation of islands with a low degree of ordering, as evidenced by the high density of low-coordinated atomic configurations, in particular CN = 4 and 5. On the contrary, islands formed upon Ag7 deposition show a higher density of atoms with CN = 6, thus indicating the formation of islands with a close-packed atomic arrangement. This combined experimental and theoretical approach, when applied to clusters of different elements, offers the perspective to reveal nonequivalent local configurations in two-dimensional (2D) materials grown using different building blocks, with potential implications in understanding electronic and reactivity properties at the atomic level.
Revisiting the Hydrogen Oxidation Reaction on Gold: The Role of Trace Impurities JM Hermann, MM Elnagar, F Loi, LA Kibler, Š Vajda, T Jacob 2026.0
Unraveling Nanoarchitectonics‐Driven Metal–Support Interactions and Size Effects Governing CO Oxidation Activity of Size‐Selected Pt Clusters on TiO2 and SnO2 Supports S Valtera, M Vaidulych, F Loi, K Oldenburg, I Barke, M Zlámalová, ... Small Structures 7 (1), e202500702 , 2026 2026.0
Limitations in determining oxidation states in condensed matter at the subnanometric scale D Perco, M Pozzo, A Berti, F Loi, P Lacovig, S Lizzit, A Kartouzian, U Heiz, ... Journal of the American Chemical Society 147 (25), 21501-21511 , 2025 2025.0 Citations: 7
The Interaction of Sub-Monolayer Ta Adatoms and Clusters with Oxygen at the Pt (111) Interface K Bertrang, T Hinke, S Kaiser, M Knechtges, F Loi, P Lacovig, ... The Journal of Physical Chemistry C 129 (13), 6511-6523 , 2025 2025.0 Citations: 1
Unraveling the interaction of Ta atoms with Pt (111) K Bertrang, T Hinke, S Kaiser, M Knechtges, F Loi, L Sbuelz, P Lacovig, ... Surfaces and Interfaces 56, 105640 , 2025 2025.0 Citations: 2
Unveiling Inequality of Atoms in Ultrasmall Pt Clusters: Oxygen Adsorption Limited to the Uppermost Atomic Layer F Loi, L Bignardi, D Perco, A Berti, P Lacovig, S Lizzit, A Kartouzian, ... Small Structures 5 (11), 2400250 , 2024 2024.0 Citations: 5
Information hidden behind a single peak in the C 1s spectrum of graphene on Ir (111) C Botta, F Loi, D Alfe, A Baraldi Applied Surface Science 646, 158913 , 2024 2024.0 Citations: 3
Oxidation of Transition and Noble Metal Size-Selected Clusters Supported on Epitaxial Graphene F Loi Università degli Studi di Trieste , 2023 2023.0
Breakdown of the correlation between oxidation states and core electron binding energies at the sub-nanoscale F Loi, M Pozzo, L Sbuelz, L Bignardi, P Lacovig, E Tosi, S Lizzit, ... Applied Surface Science 619, 156755 , 2023 2023.0 Citations: 17
The highest oxidation state observed in graphene-supported sub-nanometer iron oxide clusters D Perco, F Loi, L Bignardi, L Sbuelz, P Lacovig, E Tosi, S Lizzit, ... Communications Chemistry 6 (1), 61 , 2023 2023.0 Citations: 18
Oxidation at the sub-nanoscale: oxygen adsorption on graphene-supported size-selected Ag clusters F Loi, M Pozzo, L Sbuelz, L Bignardi, P Lacovig, E Tosi, S Lizzit, ... Journal of Materials Chemistry A 10 (27), 14594-14603 , 2022 2022.0 Citations: 12
Atomic undercoordination in Ag islands on Ru (0001) grown via size-selected cluster deposition: an experimental and theoretical high-resolution core-level photoemission study L Sbuelz, F Loi, M Pozzo, L Bignardi, E Nicolini, P Lacovig, E Tosi, S Lizzit, ... The Journal of Physical Chemistry C 125 (17), 9556-9563 , 2021 2021.0 Citations: 6
Growth Mechanism and Thermal Stability of a MoS 2 –Graphene Interface: A High-Resolution Core-Level Photoelectron Spectroscopy Study F Loi, L Sbuelz, P Lacovig, D Lizzit, L Bignardi, S Lizzit, A Baraldi The Journal of Physical Chemistry C 124 (38), 20889-20897 , 2020 2020.0 Citations: 12
MOKE setup exploiting a nematic liquid crystal modulator R Ciprian, F Loi, E Busetto, V Bonanni, B Casarin, A Caretta, M Solzi, ... Review of Scientific Instruments 89 (10) , 2018 2018.0 Citations: 4
Giant magneto–electric coupling in 100 nm thick Co capped by ZnO nanorods G Vinai, B Ressel, P Torelli, F Loi, B Gobaut, R Ciancio, B Casarin, ... Nanoscale 10 (3), 1326-1336 , 2018 2018.0 Citations: 13
Information Hidden Behind a Single Peak in the C1s Spectrum of Graphene on Ir (111) A BARALDI, C Botta, F Loi, D Alfè Available at SSRN 4576263 , 0
MOST CITED SCHOLAR PUBLICATIONS
The highest oxidation state observed in graphene-supported sub-nanometer iron oxide clusters D Perco, F Loi, L Bignardi, L Sbuelz, P Lacovig, E Tosi, S Lizzit, ... Communications Chemistry 6 (1), 61 , 2023 2023.0 Citations: 18
Breakdown of the correlation between oxidation states and core electron binding energies at the sub-nanoscale F Loi, M Pozzo, L Sbuelz, L Bignardi, P Lacovig, E Tosi, S Lizzit, ... Applied Surface Science 619, 156755 , 2023 2023.0 Citations: 17
Giant magneto–electric coupling in 100 nm thick Co capped by ZnO nanorods G Vinai, B Ressel, P Torelli, F Loi, B Gobaut, R Ciancio, B Casarin, ... Nanoscale 10 (3), 1326-1336 , 2018 2018.0 Citations: 13
Oxidation at the sub-nanoscale: oxygen adsorption on graphene-supported size-selected Ag clusters F Loi, M Pozzo, L Sbuelz, L Bignardi, P Lacovig, E Tosi, S Lizzit, ... Journal of Materials Chemistry A 10 (27), 14594-14603 , 2022 2022.0 Citations: 12
Growth Mechanism and Thermal Stability of a MoS 2 –Graphene Interface: A High-Resolution Core-Level Photoelectron Spectroscopy Study F Loi, L Sbuelz, P Lacovig, D Lizzit, L Bignardi, S Lizzit, A Baraldi The Journal of Physical Chemistry C 124 (38), 20889-20897 , 2020 2020.0 Citations: 12
Limitations in determining oxidation states in condensed matter at the subnanometric scale D Perco, M Pozzo, A Berti, F Loi, P Lacovig, S Lizzit, A Kartouzian, U Heiz, ... Journal of the American Chemical Society 147 (25), 21501-21511 , 2025 2025.0 Citations: 7
Atomic undercoordination in Ag islands on Ru (0001) grown via size-selected cluster deposition: an experimental and theoretical high-resolution core-level photoemission study L Sbuelz, F Loi, M Pozzo, L Bignardi, E Nicolini, P Lacovig, E Tosi, S Lizzit, ... The Journal of Physical Chemistry C 125 (17), 9556-9563 , 2021 2021.0 Citations: 6
Unveiling Inequality of Atoms in Ultrasmall Pt Clusters: Oxygen Adsorption Limited to the Uppermost Atomic Layer F Loi, L Bignardi, D Perco, A Berti, P Lacovig, S Lizzit, A Kartouzian, ... Small Structures 5 (11), 2400250 , 2024 2024.0 Citations: 5
MOKE setup exploiting a nematic liquid crystal modulator R Ciprian, F Loi, E Busetto, V Bonanni, B Casarin, A Caretta, M Solzi, ... Review of Scientific Instruments 89 (10) , 2018 2018.0 Citations: 4
Information hidden behind a single peak in the C 1s spectrum of graphene on Ir (111) C Botta, F Loi, D Alfe, A Baraldi Applied Surface Science 646, 158913 , 2024 2024.0 Citations: 3
Unraveling the interaction of Ta atoms with Pt (111) K Bertrang, T Hinke, S Kaiser, M Knechtges, F Loi, L Sbuelz, P Lacovig, ... Surfaces and Interfaces 56, 105640 , 2025 2025.0 Citations: 2
The Interaction of Sub-Monolayer Ta Adatoms and Clusters with Oxygen at the Pt (111) Interface K Bertrang, T Hinke, S Kaiser, M Knechtges, F Loi, P Lacovig, ... The Journal of Physical Chemistry C 129 (13), 6511-6523 , 2025 2025.0 Citations: 1
Revisiting the Hydrogen Oxidation Reaction on Gold: The Role of Trace Impurities JM Hermann, MM Elnagar, F Loi, LA Kibler, Š Vajda, T Jacob 2026.0
Unraveling Nanoarchitectonics‐Driven Metal–Support Interactions and Size Effects Governing CO Oxidation Activity of Size‐Selected Pt Clusters on TiO2 and SnO2 Supports S Valtera, M Vaidulych, F Loi, K Oldenburg, I Barke, M Zlámalová, ... Small Structures 7 (1), e202500702 , 2026 2026.0
Oxidation of Transition and Noble Metal Size-Selected Clusters Supported on Epitaxial Graphene F Loi Università degli Studi di Trieste , 2023 2023.0
Information Hidden Behind a Single Peak in the C1s Spectrum of Graphene on Ir (111) A BARALDI, C Botta, F Loi, D Alfè Available at SSRN 4576263 , 0