Surface chemistry, structure, and reactivity
of multi-component spinel nanoparticles

@article{CanoBlanco_2026b,

title = {Cooperative Redox Catalysis of N_{2}O Decomposition by Short-Range RhO_{x} and CeO_{x} Anchored to Co_{3}O_{4}},

author = {Daniel C. Cano-Blanco and Silvio Bellomi and Daniele Bonavia and Ivo Alxneit and Kirill A. Lomachenko and Karin Föttinger and Oliver Kröcher and Davide Ferri},

doi = {10.1002/anie.7890563},

year  = {2026},

date = {2026-06-23},

urldate = {2026-06-23},

journal = {Angewandte Chemie International Edition},

volume = {65},

number = {34},

pages = {e7890563},

abstract = {Hybrid materials based upon mixed metal oxides provide an effective strategy to boost catalytic performance through redox-induced interfacial engineering. Herein, we present an efficient catalyst toward N_{2}O decomposition containing short-range ordered RhO_{x} and CeO_{x} species anchored to the Co_{3}O_{4} spinel. The activity enhancement relative to Co_{3}O_{4} is non-additive with respect to the RhO_{x}/Co_{3}O_{4} and CeO_{x}/Co_{3}O_{4} interfaces and is uniquely linked to the modulation of the Co and Rh oxidation states at a synergistic Rh–O–Co–O–Ce interface. This ensemble provides increased redox flexibility and facilitated lattice oxygen activation, resulting in markedly enhanced N_{2}O decomposition. Kinetic analysis and operando modulated excitation x-ray absorption spectroscopy (ME-XAS) provide direct mechanistic evidence that N_{2}O decomposition proceeds via a multi-site, cooperative Mars-van Krevelen pathway, in which Co_{3}O_{4}–CeO_{2} acts as an oxygen reservoir enabling the redox cycling of RhO_{x} species. This study highlights the ability of mixed metal oxide catalysts to exploit interfacial effects to achieve improved activity in redox-mediated reactions and offers a rationale for the engineering of metal oxide–metal oxide catalysts guided by operando spectroscopy.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}

@article{Alves_2026a,

title = {Few-layer MoS_{2} dispersion induced by sulfur atom sharing to promote CO_{2} hydrogenation to methanol},

author = {Gustavo A. S. Alves and Silvio Bellomi and Tobias Wagner and Alberto Tampieri and Christian Etzlstorfer and Michael Stöger-Pollach and Daniel C. Cano-Blanco and Karin Föttinger},

doi = {10.1039/d6ta01545j},

year  = {2026},

date = {2026-06-05},

urldate = {2026-06-05},

journal = {Journal of Materials Chemistry A},

volume = {14},

number = {44},

pages = {29662-29671},

abstract = {With the ongoing interest in developing more stable and versatile catalysts for CO_{2} hydrogenation to methanol, molybdenum sulfide (MoS_{2}) has been recently proposed as an alternative material. However, in its bulk state, CO_{2} hydrogenation over MoS_{2} typically favors methane formation. In this work, a wet impregnation method is applied for the production of ZnS-supported MoS_{2}, as confirmed by characterization via X-ray Diffraction, Raman and X-ray Photoelectron Spectroscopy. In contrast with the negligible methanol production shown by the pure MoS_{2} reference, 2% MoS_{2}/ZnS presents a methanol selectivity of 78% at a CO_{2} conversion of 2.3% under the mild reaction conditions of 200 °C and 20 bar. Density Functional Theory and Transmission Electron Microscopy suggest that the improved catalytic activity arises from an even dispersion of few-layer MoS_{2} with exposed basal plane sites at the ZnS surface, an arrangement possibly enabled by the structural similarity and the shared S atoms between 2H-MoS_{2} and W–ZnS phases. This hypothesis is strengthened by the comparison with the reference sample consisting of ZrO_{2}-supported MoS_{2} sample, in which more agglomerated MoS_{2} particles resulted in a lower and less selective methanol production. Moreover, in situ X-ray absorption spectroscopy and H_{2} temperature-programmed reduction suggest further evidence of a MoS_{2}/ZnS interaction during the H_{2} pretreatment, which may promote not only the expected formation of S-vacancies but also a partial reconstruction of MoS_{2} given the close contact and sharing of S atoms with the ZnS support.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}

@article{Corrias_2026a,

title = {Total Variation-Based Image Decomposition and Denoising for Microscopy Images},

author = {Marco Corrias and Giada Franceschi and Michele Riva and Alberto Tampieri and Karin Föttinger and Ulrike Diebold and Thomas Pock and Cesare Franchini},

doi = {10.1093/mam/ozag031},

year  = {2026},

date = {2026-05-12},

urldate = {2026-05-12},

journal = {Microscopy and Microanalysis},

volume = {32},

issue = {3},

pages = {ozag031},

abstract = {Experimentally acquired microscopy images are unavoidably affected by the presence of noise and other unwanted signals, which degrade their quality and might hide relevant features. With the recent increase in image acquisition rate, modern denoising and restoration solutions become necessary. This study focuses on image decomposition and denoising of microscopy images through a workflow based on total variation (TV), addressing images obtained from various microscopy techniques, including atomic force microscopy (AFM), scanning tunneling microscopy (STM), and scanning electron microscopy (SEM). Our approach consists in restoring an image by extracting its unwanted signal components and subtracting them from the raw one, or by denoising it. We evaluate the performance of TV-\textit{L}^{1}⁠, Huber-ROF, and TGV-\textit{L}^{1} in achieving this goal in distinct study cases. Huber-ROF proved to be the most flexible one, while TGV-\textit{L}^{1} is the most suitable for denoising. Our results suggest a wider applicability of this method in microscopy, restricted not only to STM, AFM, and SEM images. The Python code used for this study is publicly available as part of AiSurf. It is designed to be integrated into experimental workflows for image acquisition or can be used to denoise previously acquired images.},

keywords = {P02, P07, P10},

pubstate = {published},

tppubtype = {article}

}

@article{Barlocco_2026a,

title = {Influence of nitrogen functional groups in carbon-based supports anchoring Pt nanoclusters and single atoms for efficient ammonia borane hydrolysis},

author = {Ilaria Barlocco and Silvio Bellomi and Bianca M. C. Anghinelli and Xiaowei Chen and Juan J. Delgado and Marta Stucchi and Laura Prati and Karin Föttinger and Alberto Villa},

doi = {10.1039/D5CC06925D},

year  = {2026},

date = {2026-02-05},

urldate = {2026-02-05},

journal = {Chemical Communications},

abstract = {A Pt(II) precursor was impregnated onto graphite (C) and carbon nitride (CN_{x}), successfully forming subnanometric Pt clusters and single atoms. The N species on CN_{x} modified the electronic and topological structure of the metal, improving the catalytic properties of the Pt/CN_{x} catalyst in evolving hydrogen from NH_{3}BH_{3}. This was rationalised by combining HR-TEM and XPS characterisation with DFT computational analysis.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}

@article{CanoBlanco_2025a,

title = {Comparative study of multi-element modification and rhodium promotion of Co_{3}O_{4}-based spinel catalysts for N_{2}O decomposition},

author = {Daniel C. Cano-Blanco and Jarne van Aubel and Silvio Bellomi and Ivo Alxneit and Karin Föttinger and Oliver Kröcher and Davide Ferri},

doi = {10.1016/j.apcata.2025.120681},

year  = {2026},

date = {2026-01-25},

urldate = {2026-01-25},

journal = {Applied Catalysis A: General},

volume = {710},

pages = {120681},

abstract = {The removal of nitrous oxide (N_{2}O) from industrial flue gases remains a significant environmental challenge due to the intrinsic kinetic stability of the N_{2}O molecule. Among available abatement technologies, the direct catalytic decomposition of N_{2}O into harmless N_{2} and O_{2} (deN_{2}O) represents a promising, reagent-free solution. In this study, we systematically screened a series of catalysts obtained from Co_{3}O_{4} by addition of transition elements, magnesium and aluminum (10 wt%), and analog series with addition of rhodium (Rh; 1 wt%), from which Co-Al-Rh emerged as the most active catalyst formulation. Characterization by H_{2}-TPR and XPS indicated improvement in the redox performance and increasing weakening of the Co-O bond upon addition of a second element and of Rh. The addition of Rh resulted also in a significant enhancement in catalytic activity. Complementary kinetic studies revealed a shift in the rate-determining step (RDS) between N-O bond cleavage and O_{2} desorption, depending on catalyst composition. These results highlight the critical role of Co-O bond weakening in facilitating oxygen mobility and promoting activity.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}

@article{Tampieri_2025a,

title = {Phase-Dependent Catalytic Oxidation of Secondary Alcohols Using Spinel Cobaltite Catalysts Under Liquid- and Gas-Phase Flow Conditions},

author = {Alberto Tampieri and Federica Romanelli and Michael Pittenauer and Thomas Lederer and Karin Föttinger},

doi = {10.1002/cctc.202500778},

year  = {2025},

date = {2025-08-15},

urldate = {2025-08-15},

journal = {ChemCatChem},

pages = {e00778},

abstract = {Selective partial oxidation of alcohols is a straightforward synthetic pathway to access aldehydes and ketones, important building blocks for the chemical industry. The catalytic oxidation of higher secondary alcohols is challenging, which entails the need for low temperatures to preserve the selectivity or, in practice, the use of a liquid phase. In this work, we explored the applicability of Co-based spinel oxides as alternatives to noble metal-based supported catalysts for the oxidation of alcohols such as 2-butanol and 2-propanol. We developed a small-scale tri-phasic process in flow operable for consecutive weeks and using technical grade porous catalysts, en route to more industrially-relevant systems, focusing on the practical aspects of the process. Co_{3}O_{4}, MnCo_{2}O_{4}, NiCo_{2}O_{4}, ZnCo_{2}O_{4}, and CoFe_{2}O_{4} were synthesized by combustion and characterized by XRD, SEM, EDX, XPS, N_{2}-physisorption, and FT-IR spectroscopy. The same catalysts were tested in batch in the liquid phase to explore the impact of the reaction conditions on the reaction outcome and to rule out flow-specific effects. Gas phase reactions unveiled the different behavior of the same catalysts in different environments, highlighting phase-specific effects such as the beneficial (liquid phase) versus inhibiting (gas phase) impact of Mn doping.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}

@article{Amin_2025a,

title = {Switchable Behavior of Ru–TiO_{2} Catalysts in HMF Conversion},

author = {Babar Amin and Jaroslav Aubrecht and Oleg Kikhtyanin and Evgeniya Grechman and Gustavo Andrade Silva Alves and Alberto Tampieri and Karin Föttinger and Marcin Jędrzejczyk and Agnieszka M. Ruppert and Francisco Ruiz-Zepeda and David Kubička},

doi = {10.1021/acssuschemeng.5c04908},

year  = {2025},

date = {2025-07-17},

urldate = {2025-07-17},

journal = {ACS Sustainable Chemistry & Engineering},

volume = {13},

issue = {29},

pages = {11652-11667},

abstract = {5-Hydroxymethylfurfural (HMF) is a platform chemical that can be catalytically valorized into high-value-added chemicals. Despite the extensive use of titania-supported metal catalysts in HMF conversion, the specific influence of the TiO_{2} support on the formation of metal active sites, their dispersion, and their role in HMF conversion is not addressed sufficiently. In this work, we investigated five TiO_{2} supports, four anatase- and one rutile-dominant, varying in surface area and acidity, which were loaded with 1 wt % Ru using RuCl_{3}. Characterization results revealed that the Ru environment, charge distribution, and surface features (transition from Ru–Cl to Ru–O species) varied depending on the TiO_{2} support used. Their catalytic performance was assessed in HMF hydrogenation. Despite identical Ru loadings, the Ru/TiO_{2} catalysts exhibited remarkably different catalytic activities and selectivity. High-surface-area anatase TiO_{2} led to the formation of smaller Ru particles and supported the conversion of HMF to 5-methylfurfural. In contrast, lower surface area anatase and rutile supports favored the formation of larger Ru particles and redirected the reaction course from 5-MF toward the hydrogenation route, yielding primarily 2,5-bis(hydroxymethyl)furan. This study revealed the switchable behavior of Ru/TiO_{2} catalysts and exposed the critical role of TiO_{2} structural and morphological features for reaction pathways in HMF valorization over Ru/TiO_{2}. These insights provide a refined framework for the rational design of oxide-supported catalysts tailored for the selective conversion of biomass.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}

@article{Yigit_2024a,

title = {Preferential CO oxidation (PROX) on LaCoO_{3}–based catalysts: Effect of cobalt oxidation state on selectivity},

author = {Nevzat Yigit and Karin Föttinger and Johannes Bernardi and Günther Rupprechter},

url = {https://doi.org/10.1016/j.jcat.2025.115973},

year  = {2025},

date = {2025-01-20},

urldate = {2025-01-20},

journal = {Journal of Catalysis},

issue = {0021-9517},

pages = {115973},

abstract = {The perovskite LaCoO_{3} (LCO) was used as catalyst for preferential oxidation of CO (PROX). LCO was synthesized via the modified Pechini method and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and CO_{2–} and H_{2–} temperature programmed reduction (TPR). Different reductive and oxidative pretreatments were applied to systematically vary the Co oxidation state in order to examine its effect on catalytic performance and to single out active site requirements. Upon reduction at increasing temperature, LaCoO_{3} transformed to brownmillerite-type La_{2}Co_{2}O_{5}, exsolved Co^{0} nanoparticles supported on La_{2}O_{3} and, upon reoxidation, to Co_{3}O_{4}/La_{2}O_{3}. The Co oxidation state of the various catalysts correlated with their CO_{2} selectivity: LCO containing only Co^{3+} exhibited 100 % CO_{2} selectivity in a wide temperature window, whereas La_{2}Co_{2}O_{5}, Co/La_{2}O_{3} and Co_{3}O_{4}/La_{2}O_{3} had markedly lower selectivity. It is suggested that Co^{3+} is crucial and that the strong resistivity of LaCoO_{3} towards reduction is responsible for the high and stable CO_{2} selectivity over a temperature range of 100 °C–220 °C. Higher oxygen concentration further broadens the PROX window.},

keywords = {P08, P10},

pubstate = {published},

tppubtype = {article}

}

@article{Rakngama_2024a,

title = {Hydrothermal synthesis of ZnZrO_{x} catalysts for CO_{2} hydrogenation to methanol: the effect of pH on structure and activity},

author = {Issaraporn Rakngam and Gustavo A. S. Alves and Nattawut Osakoo and Jatuporn Wittayakun and Thomas Konegger and Karin Föttinger},

doi = {10.1039/D4SU00522H},

year  = {2024},

date = {2024-10-11},

urldate = {2024-10-11},

journal = {RSC Sustainability},

volume = {2},

issue = {12},

pages = {3798-3805},

abstract = {With the growing necessity of achieving carbon neutrality in the industrial sector, the catalytic hydrogenation of carbon dioxide into methanol has been widely considered one of the key strategies for the utilization of captured CO_{2}. For this reason, the development of alternative catalysts such as ZnZrO_{x} has attracted considerable interest, given its superior stability and versatility in comparison to the conventional Cu-based materials. In this work, ZnZrO_{x} has been produced by a hydrothermal synthesis method at varied synthesis pH between 7 and 10 and a positive association between pH and catalytic CO_{2} conversion is observed. At 2.0 MPa and 250 °C, ZnZrO_{x} produced at pH 10 shows a methanol selectivity of 95% at a CO_{2} conversion of 3.4%. According to characterization, basic pH conditions enable the formation of abundant t-ZrO_{2} and the subsequent incorporation of Zn^{2+} into this phase, although the content of surface Zn does not increase between pH 8 and 10. Nevertheless, synthesis pH values can be correlated with surface oxygen content and CO_{2} adsorption capacity, which could be important contributors to the higher catalytic activity observed as a result of higher synthesis pH values. Finally, the comparison between NaOH and NH_{4}OH as additives to adjust pH 10 indicate similar catalytic activities and surface properties, which emphasizes the proposed trend between hydrothermal synthesis pH and catalytic activity for CO_{2} hydrogenation.},

keywords = {P10},

pubstate = {published},

tppubtype = {article}

}