A5087981820- Catalytic Processes in Materials Science
- Iron oxide chemistry and applications
- Electrocatalysts for Energy Conversion
- Catalysis and Oxidation Reactions
- Minerals Flotation and Separation Techniques
- Surface Chemistry and Catalysis
- Electronic and Structural Properties of Oxides
- Magnetic Properties and Synthesis of Ferrites
- Nanomaterials for catalytic reactions
- Advanced Chemical Physics Studies
- Catalysts for Methane Reforming
- Metal-Organic Frameworks: Synthesis and Applications
- Graphene research and applications
- Surface and Thin Film Phenomena
- Mine drainage and remediation techniques
- Copper-based nanomaterials and applications
- nanoparticles nucleation surface interactions
- Clay minerals and soil interactions
- Thermal Radiation and Cooling Technologies
- Chemical and Physical Properties of Materials
- Cyclopropane Reaction Mechanisms
- X-ray Diffraction in Crystallography
- Organic Chemistry Cycloaddition Reactions
- Civil and Structural Engineering Research
- Radioactive element chemistry and processing
Central European Institute of Technology
2022-2025
Brno University of Technology
2022-2025
TU Wien
2017-2024
Robert Bosch (Germany)
2024
Institut für Technische und Angewandte Physik (Germany)
2024
Understanding how the local environment of a "single-atom" catalyst affects stability and reactivity remains challenge. We present an in-depth study copper1, silver1, gold1, nickel1, palladium1, platinum1, rhodium1, iridium1 species on Fe3O4(001), model support in which all metals occupy same twofold-coordinated adsorption site upon deposition at room temperature. Surface science techniques revealed that CO strength single metal sites differs from respective surfaces supported clusters....
The α-Fe2O3(11̅02) surface (also known as the hematite r-cut or (012) surface) was studied using low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), ultraviolet (UPS), scanning tunneling microscopy (STM), noncontact atomic force (nc-AFM), and ab initio density functional theory (DFT)+U calculations. Two structures are stable under ultrahigh vacuum (UHV) conditions; a stoichiometric (1 × 1) can be prepared by annealing at 450 °C in ≈10–6 mbar O2, reduced (2...
Significance Determining the structure of water on metal oxide surfaces is a key step toward molecular-level understanding dissolution, corrosion, geochemistry, and catalysis, but hydrogen bonding large, complex unit cells present major challenge to modern theory. Here, we utilize state-of-the-art experimental techniques guide density functional theory (DFT)-based search for minimum-energy configurations Fe 3 O 4 (001). A subsurface reconstruction dominates adsorption at all coverages. An...
The functionality of 2D metal-organic frameworks (MOFs) is crucially dependent on the local environment embedded metal atoms. These atomic-scale details are best ascertained MOFs supported well-defined surfaces, but interaction with support often changes MOF properties. We elucidate extent this effect by comparing Fe-TCNQ two weakly interacting supports: graphene and Au(111). show that nonplanar iron in quasi-tetrahedral sites, Au(111) it planarized stronger van der Waals interaction....
The adsorption of $CO_2$ on the $Fe_3$$O_4$(001)-($\sqrt{2}$ $\times$ $\sqrt{2}$)R45{\deg} surface was studied experimentally using temperature programmed desorption (TPD), electron spectroscopies (UPS and XPS), scanning tunneling microscopy (STM). binds most strongly at defects related to Fe2+ including antiphase domain boundaries in reconstruction above incorporated Fe interstitials. On pristine surface, adsorbs molecularly fivefold-coordinated Fe3+ sites with a binding energy 0.4 eV....
Abstract Single‐atom catalysts (SACs) bridge homo‐ and heterogeneous catalysis because the active site is a metal atom coordinated to surface ligands. The local binding environment of should thus strongly influence how reactants adsorb. Now, atomically resolved scanning‐probe microscopy, X‐ray photoelectron spectroscopy, temperature‐programmed desorption, DFT are used study CO binds at different Ir 1 sites on precisely defined Fe 3 O 4 (001) support. two‐ five‐fold‐coordinated adatoms bind...
Heterogeneous catalysts based on subnanometer metal clusters often exhibit strongly size-dependent properties, and the addition or removal of a single atom can make all difference. Identifying most active species deciphering reaction mechanism is extremely difficult, however, because it not clear how catalyst evolves in operando. Here, we use combination atomically resolved scanning probe microscopies, spectroscopic techniques, density functional theory (DFT)–based calculations to study CO...
The oxygen evolution reaction (OER) is thought to occur via a four-step mechanism with *O, *OH, and *OOH as adsorbed intermediates. Linear scaling of the *OH **OOH adsorption energies proposed limit oxides' efficiency OER catalysts, but use simple descriptors screen candidate materials neglects potentially important water–water interactions. Here, we combination temperature-programmed desorption (TPD), X-ray photoemission spectroscopy (XPS), noncontact atomic force microscopy (nc-AFM),...
The structure of a catalyst often changes in reactive environments, and following the structural evolution is crucial for identification catalyst's active phase reaction mechanism. Here we present an atomic-scale study CO oxidation on model Rh/Fe3O4(001) "single-atom" catalyst, which has very different depending two reactants, O2 or CO, adsorbed first. Using temperature-programmed desorption (TPD) combined with scanning tunneling microscopy (STM) X-ray photoelectron spectroscopy (XPS), show...
Oxide-supported single-atom catalysts are commonly modeled as a metal atom substituting surface cation sites in low-index surface. Adatoms with dangling bonds will inevitably coordinate molecules from the gas phase, and adsorbates such water can affect both stability catalytic activity. Herein, we use scanning tunneling microscopy (STM), noncontact atomic force (ncAFM), X-ray photoelectron spectroscopy (XPS) to show that high densities of single Rh adatoms stabilized on α-Fe2O3(11̅02)...
Electrochemical water splitting is an environmentally friendly technology to store renewable energy in the form of chemical fuels. Among earth-abundant first-row transition metal-based catalysts, mixed Ni-Fe oxides have shown promising performance for effective and low-cost catalysis oxygen evolution reaction (OER) alkaline media, but synergistic roles Fe Ni cations OER mechanism remain unclear. In this work, we report how addition changes reactivity a model iron oxide catalyst, based on...
Detailed atomic-scale understanding is a crucial prerequisite for rational design of next-generation single-atom catalysts (SACs). However, the sub-ångström precision needed systematic studies challenging to achieve on common SACs. Here, we present two-dimensional (2D) metal-organic system featuring Fe-N4 sites, where structure modulated by 0.4 Å corrugation an inert graphene/Ir(111) support. Using scanning tunneling microscopy and density functional theory, show that support significantly...
Benchmarking DFT calculations against precise normal incidence X-ray standing wave measurements.
The ability to coordinate multiple reactants at the same active site is important for wide-spread applicability of single-atom catalysis. Model catalysts are ideal investigate link between geometry and reactant binding, because structure single-crystal surfaces can be precisely determined, adsorbates imaged by scanning tunneling microscopy (STM), direct comparisons made density functional theory. In this study, we follow evolution Rh
The interaction of CO with the Fe3O4(001)-(√2 × √2)R45° surface was studied using temperature-programmed desorption (TPD), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS), latter both under ultrahigh vacuum (UHV) conditions in pressures up to 1 mbar. In general, CO–Fe3O4 is found be weak. strongest adsorption occurs at defects, leading small TPD peaks 115, 130, 190 K. Desorption from regular two distinct regimes. For coverages molecules per (√2 unit cell,...
The normal incidence X-ray standing wave (NIXSW) technique has been used to follow the evolution of adsorption geometry Ni adatoms on Fe3O4(001)-(√2 × √2)R45° surface as a function temperature. Two primary region sites are identified: bulk-continuation tetrahedral site and sub-surface octahedral site, latter being preferred at higher annealing temperatures. ease incorporation is linked presence subsurface cation vacancies in (√2 reconstruction consistent with preference for coordination...
Atomic-scale investigations of metal oxide surfaces exposed to aqueous environments are vital understand degradation phenomena (e.g. dissolution and corrosion) as well the performance these materials in applications. Here, we utilize a new experimental setup for UHV-compatible dosing liquids explore stability Fe3O4(001)-c(2x2) surface following exposure liquid ambient pressure water. X-ray photoelectron spectroscopy (XPS) low energy electron diffraction (LEED) data show that extensive...
The interaction of water with the most prominent surfaces Fe3O4, (001) and (111), is directly compared using a combination temperature-programmed desorption, low energy electron diffraction (TP LEED), scanning probe microscopies. Adsorption on (√2 × √2)R45°-reconstructed surface Fe3O4(001) strongly influenced by reconstruction, which remains intact at all coverages. Close to completion first monolayer, however, ad-layer adopts longer-range (2 2) superstructure. This finding discussed in...
Abstract Iron oxides (FeO x ) are among the most common support materials utilized in single atom catalysis. The is nominally Fe 2 O 3 , but strongly reductive treatments usually applied to activate as‐synthesized catalyst prior use. Here, Rh adsorption and incorporation on () surface of hematite (α‐Fe studied, which switches from a stoichiometric (1 × 1) termination reduced (2 reconstruction reducing conditions. atoms form clusters at room temperature both terminations, incorporate into...
Abstract Oxygen exchange at oxide/liquid and oxide/gas interfaces is important in technology environmental studies, as it closely linked to both catalytic activity material degradation. The atomic-scale details are mostly unknown, however, often ascribed poorly defined defects the crystal lattice. Here we show that even thermodynamically stable, well-ordered surfaces can be surprisingly reactive. Specifically, all 3-fold coordinated lattice oxygen atoms on a defect-free single-crystalline...
In polarizable materials, electronic charge carriers interact with the surrounding ions, leading to quasiparticle behavior. The resulting polarons play a central role in many materials properties including electrical transport, interaction light, surface reactivity, and magnetoresistance, are typically investigated indirectly through these macroscopic characteristics. Here, noncontact atomic force microscopy (nc-AFM) is used directly image Fe
We studied how nickel doping affects water adsorption at the Fe3O4(001) surface to understand enhanced performance of spinel ferrites for water-gas shift and oxygen evolution reactions. Two different configurations were prepared: 2-fold-coordinated Ni adatoms on top atoms incorporated into octahedral sites support. Using temperature-programmed desorption, X-ray photoemission spectroscopy, scanning tunneling microscopy, we show that is adsorbed dissociated room temperature, resulting in Ni–OH...
Polarizable materials attract attention in catalysis because they have a free parameter for tuning chemical reactivity. Their surfaces entangle the dielectric polarization with surface polarity, excess charge, and orbital hybridization. How this affects individual adsorbed molecules is shown incipient ferroelectric perovskite KTaO3. This intrinsically polar material cleaves along (001) into KO- TaO2-terminated domains. At TaO2 terraces, polarity-compensating electrons form two-dimensional...