Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
Abstract view at TH poster session in building A (2nd floor) on Nov. 25th, 2024, from 2:00 pm.
We present on the realization of the first Bose-Einstein-Condensate of Dysprosium atoms. We present details about the experimental techniques, i.e. laser cooling and evaporative cooling, that allow us to increase the phase-space density of our gas until the onset of Bose-Einstein Condensation, signaled by the emergence of a bimodal distribution in time-of-flight.
The goal of our experiment is to study how optical cavities can modify ultracold reactions. To do so, we need to upgrade our ultracold dysprosium experiment by including two new elements in the science chamber. 1) A high-finesse optical cavity for controlling light-matter coupling. 2) An ion optics system for detecting reaction products. This requires the development of a new atomic source,...
Since 2013 the infrared FEL at the Fritz Haber Institute (FHI FEL) has been providing intense, pulsed mid-infrared (MIR) radiation, continuously tunable from <3 μm to >50 μm for in-house users. This has resulted in more than 100 peer-reviewed publications so far. In 2023 an additional short-Rayleigh-range far-infrared (FIR) FEL has been commissioned lasing from <5 μm to >170 μm. In addition, a...
In 1896, Edward Charles Pickering (1846-1919), Director of the Harvard College
Observatory (HCO), reported in a trio of publications the observation of “peculiar
spectra” of the southern star ζ Puppis, which he attributed to an “element not yet
found in other stars or on earth.” Supported by laboratory spectra obtained by Alfred
Fowler (1868-1940), Niels Bohr (1885-1962) showed in 1913...
We present a combined experimental and theoretical investigation of the radiationless decay spectrum of an O 1s double core hole in liquid water. Our experiments were carried out using liquid-jet electron spectroscopy from cylindrical microjets of normal and deuterated water. The signal of the double-core-hole spectral fingerprints (hypersatellites) of liquid water is clearly identified, with...
Photoelectron circular dichroism (PECD) has emerged as an extremely sensitive probe of the molecular and electronic structure of chiral molecules, but its suitability for application to aqueous solutions had not yet been proven. Here, we provide an update on our recent PECD measurements of aqueous-phase alanine, the simplest chiral amino acid. We demonstrate that the PECD response of alanine...
Intermolecular Coulombic decay (ICD) is a non-local autoionization process that has the potential to selectively probe the first hydration shell of solvated molecules. Here, we demonstrate the applicability of ICD spectroscopy to biomolecules in a complex environment. Firstly, we access site-specific information on the interaction of adenosine triphosphate in the aqueous phase (ATP(aq)) with...
Tens-of-µm-sized liquid jets have revolutionized experimental research on the physical chemistry of aqueous solutions. Our work on improved liquid jet techniques unlocks further interesting opportunities in this field.
We show first results of a novel set-up that enables velocity map imaging (VMI) of electrons emitted from a liquid jet, thus allowing the measurement of the full angular and...
Liquid microjets (liquid jets, LJ), introduced in the 80s–90s by M. Faubel, S. Schlemmer and J.P. Toennies, enabled the investigation of volatile liquids under high-vacuum conditions and opened a breadth of new fields [1]. One of such fields is the combination of LJs with photoelectron spectroscopy, LJ–PES, capable of revealing subtle energy shifts in molecular-orbital binding energies (BEs)...
The ytterbium monofluoride (YbF) molecule has gained attention for being a system well-suited for measuring the electric dipole moment of the electron (eEDM). In this work we present REMPI measurements of Rydberg states, i.e. states with a single (highly) excited electron, of YbF. Assignment of these measured Rydberg states to series that converge to various rotational and vibrational levels...
Photoelectron Circular Dichroism (PECD) is a chiral optical effect that manifests in the angle-dependent photoemission of an electron upon irradiation of a chiral molecule by circularly polarized light. PECD can aid in our fundamental understanding of electron dynamics as this effect is acutely sensitive to the molecular state and electron emission conditions. The magnitude and sign of PECD...
The stereochemistry and conformational flexibility of chiral molecules have a strong impact on their biological, biochemical, and pharmacological properties. A central analytical challenge is the generally applicable differentiation of enantiomers, as well as the fast and accurate determination of the enantiomeric excess of a chiral sample.
Gas phase vibrational action spectroscopy is a...
Studies on metal oxide clusters in the gas phase are aimed at gaining a better atomistic understanding of single-site catalysts. Here, we study the structure and reactivity of cationic model systems using a combination of mass spectrometry, infrared photodissociation (IRPD) spectroscopy, ion mobility and electronic structure calculations ranging from density functional theory to...
We present our recent progress on laser cooling AlF molecules using deep lasers. AlF is distinctively different from the molecular species that have been laser-cooled so far: it is a stable molecule that can be produced in large quantities and it has a strong $A^1\Pi\leftarrow X^1\Sigma^+$ transition near 227.5 nm that can be used for rapid slowing and cooling in a magneto-optical trap (MOT)...
Aluminum monofluoride (AlF) is a promising candidate for laser cooling and trapping experiments. To support research in this area, we have developed the AlF Spectroscopy Database (alf.mp.fhi-berlin.mpg.de), which features the latest spectroscopic constants for the AlF molecule across multiple electronic states.
The database is hosted on an interactive website that enables users to compute...
We have developed a Python-based toolkit designed to investigate the dynamic properties of molecular systems using molecular dynamics (MD) simulation techniques. The toolkit supports simulations under various ensembles, including the microcanonical (NVE), canonical (NVT), isoenthalpic–isobaric (NPH), and isothermal–isobaric (NPT) ensembles, enabling the study of diverse dynamic processes and...
Beyond chiral analysis, Enantiomer-Specific State Transfer (ESST) enables the control and manipulation of chiral molecules at the quantum level. Using tailored microwave fields, a chosen rotational state can be enriched for a selected enantiomer. Although ESST can theoretically achieve 100% transfer efficiency, early ESST studies reported only modest state-specific enantiomeric enrichment,...
In this poster, we present near-complete chiral selection in rotational quantum states [1]. In our study we combine UV laser and microwave radiation to realize near-ideal initial conditions for Enantiomer-Specific State Transfer (ESST). With this we overcome previous limitations of ESST due to initial thermal population in all three states in a triad of rotational states connected to the...
We present high-resolution UV spectra of three different chiral molecules — 1-Indanol, Styrene oxide and 1-Phenylethanol. All of these molecules are interesting candidates for performing experiments on enantiomer-specific quantum state control.
We show vibrationally resolved REMPI spectra together with theoretical predictions to facilitate assignment of the transitions. We also...
Gas-phase vibrational spectroscopy has been proven to provide a nearly ideal method for the investigation of ions, unperturbed by solvent effects. In addition, ions can be placed in helium nanodroplets as a matrix, where the interaction with the dopant ion is very weak. As the helium droplets are at very low temperatures (0.37 K), thermal broadening and therefore spectral congestion is...
Ultracold helium nanodroplets provide an ideal matrix for gas-phase vibrational spectroscopy, reducing thermal broadening and spectral congestion while unperturbed significantly by solvent effects and interactions with dopant ions. In the experiment, ions are embedded in a helium droplet and irradiated with a burst-mode infrared free electron laser (FEL). Resonant absorption of photons from...
Cryogenic Infrared action spectroscopy has been proven to be effective for the experimental characterization of the vibrational modes of a large variety of molecular ions and ionic clusters in the gas phase[i]. Here, the ion of interest is isolated by a quadrupole mass filter and accumulated in a hexapole ion trap, where is traversed by a beam of helium nanodroplets that pick up the selected...
Exposure of human body to ultraviolet light can induce formation of dimeric crosslinks at bipyrimidine sites within deoxyribonucleic acid. Nucleotide excision repair enzymes normally recognize the crosslinks and remove them. In-born genetic mutations of the enzymes result in severe photosensitivity and high risk of skin cancer. Completely avoiding sun or consuming medication for pain-free...
Conventional condensed-phase bioanalytical approaches often require large amounts of high-purity samples and are, therefore, not universally applicable. Mass spectrometry (MS), on the other hand, requires only minute sample amounts and its purity is often not a critical factor. Although, the extent of structural information obtained directly by MS is limited,it can be combined with...
FHI-aims (Fritz Haber Institute ab initio materials simulations) [1-3] is a versatile electronic-structure software package developed for computational studies in molecular and materials science. Widely used by a global network of developers, researchers at the Fritz Haber Institute, academic institutions, and industry, FHI-aims leverages numeric atom-centered basis sets to deliver...
A highly intricate interplay of underlying processes governs certain materials properties and functions. This prevents a realistic description by physical models or atomistic simulations. AI can identify nonlinear correlations between materials’ parameters and the measured performance. Thus, AI might better capture the materials’ behavior compared to the theory of the past. However, the data...
Sequential active learning (SAL)-driven workflows can efficiently guide experiments and simulations towards the discovery of materials with desired properties [1]. However, AI and machine-learning approaches commonly used in these workflows rely on the knowledge of key physical parameters describing the materials property of interest. These low-dimensional representations are typically...
Widely used machine-learning (ML) approaches in materials science and catalysis are designed to accurately describe, in average, a wide range of materials. Nonetheless, only a handful of compounds might show the desired properties to be suitable for a given application. Thus, global ML models may overlook these statistically exceptional materials of interest. Here, we discuss how the...
An accurate first-principles description of the electronic band structure at finite temperatures is the prerequisite to quantitatively predict the electronic and optical properties of real materials. Theoretically, this requires proper consideration of the self-energy contributions from both electron-electron (e-e) and electron-vibration (e-vib) interactions. For the latter, the widely used...
Molecular dynamics (MD) has been popularly utilized to understand the dynamical properties of materials such as thermal, electrical, and ionic conductivities. Ab initio MD provides universal, high-quality predictions for energy, forces, and stress of any material, but its usage is limited due to high computational costs. Recent machine-learned interatomic potentials (MLIPs), with their...
First-principles approaches for phonon-limited electronic transport are typically based on many-body perturbation theory [1] and thus rely on the validity of a quasi-particle picture for phonons and electrons. However, both these pictures can become questionable in strongly anharmonic systems [2,3]. We overcome this hurdle by combining ab initio molecular dynamics (aiMD) calculations with...
The physical response of condensed matter is determined by the microscopic interactions between internal degrees of freedom, such as charge, spin, or lattice. Ultrafast methods provide insights into these interactions by studying a materials ultrafast nonequilibrium response, which helps us to understand how macroscopic material properties arise from oftentimes complex microscopic...
Charged aqueous interfaces are the subject of extensive investigation due to their prevalence in both natural and industrial processes, with importance ranging across the biological, environmental, and chemical sciences. At such phase boundaries, the excess surface charge generates an electric field that penetrates through the electrolyte, perturbing the ion distributions and electric...
Liquid-vapor interfaces play a crucial role in the atmosphere. Their composition can alter compared to the bulk. We investigate complex acid-base equilibria, including tautomers and short-lived species, at the liquid-vapor interface with photoelectron spectroscopy.
The angular momentum of lattice vibrations — phonon angular momentum — is a largely unexplored degree of freedom in solid-state systems, playing a key role in the understanding of ultrafast demagnetization processes and offering new pathways for phonon-driven ultrafast material control, particularly relevant to spintronics and valleytronics. While this research area is rapidly growing, phonon...
The geometry of atoms in molecules and materials governs their properties. The controlled manipulation of their arrangement on the atomic scale is however limited with current technology.
This work explores non-contact atomic force microscopy (NC-AFM) as one possible tool to achieve this goal. Individual molecules of nonahelicene ([9]H) and coronene (Cor) are studied on a Ag(110)-surface and...
Cavity electrodynamics offers a unique avenue for tailoring ground-state material properties, excited-state engineering, and versatile control of quantum matter. Merging these concepts with high-field physics in the terahertz (THz) spectral range opens the door to explore low-energy, field-driven cavity electrodynamics, emerging from fundamental resonances or order parameters. Despite this...
*Tommaso Pincelli, Lawson T. Lloyd, Alessandro de Vita, Tania Mukherjee, Túlio de Castro, Amine Wahada, Roberto Sant$^a$, Srdjan Stavrič$^b$, Silvia Picozzi$^b$, Nathan P. Wilson$^c$, Zdeněk Sofer$^d$, Martin Wolf, Laurenz Rettig, Ralph Ernstorfer
$^a$Politecnico di Milano, Milano, Italy
$^b$Consiglio Nazionale delle Ricerche, Chieti, Italy
$^c$Walter Schottky Institute, Technische...
Surface phonon polaritons (SPhPs) are quasiparticles resulting from the hybridisation of IR photons with transverse optical phonons. The extreme light confinement, the low losses due to the long phonon lifetimes and the high directionality that can result from low crystal symmetries are among the factors that have made phonon polaritons so attractive to the nanophotonics community in the last...
Delving the rich dynamics of many-body quantum systems represents a profound challenge in both fundamental and applied science. This challenge arises due to the intricate correlation between carriers and nuclei, which entails complex dynamic processes occurring across timescales ranging from attoseconds to picoseconds. These processes include electronic and structural phase transitions, Mott...
Aqueous solution-vapor interfaces play a major role in atmospheric processes, for example in the interaction of the oceans or of aqueous aerosols with trace gases [1]. The largest contiguous aqueous-vapor interface is that of the oceans with air, covering more than 70% of the Earth’s surface [2]. Studies have shown that the ocean-air interface is covered by a thin film of amphiphilic...
1T-TaS$_2$ is a strongly correlated material characterized by a rich phase diagram
hosting a commensurate charge density wave (C-CDW) phase at low temperatures
accompanied by the opening of an insulating gap. These properties arise from the
interaction between electronic and lattice degrees of freedom, making 1T-TaS$_2$ a
prototype material for studying the complex quantum...
Antiferromagnetic (AF) spintronics is a promising route towards more efficient and stable devices, because antiferromagnets are less susceptible to external fields and foster a broad range of magnetic interactions with the potential for higher speeds and energy efficient manipulation. However, their self-cancelling magnetic moment makes the interaction with magnetic order challenging. One way...
Tommaso Pincelli, Lawson T. Lloyd, Amine Wahada, Zoè de Granrut, Alexander Enders, Tania Mukhejee, Túlio de Castro, Alessandro de Vita, Samuel Beaulieu, Maciej Dendzik, Shuo Dong, Holger Oertel, Martin Wolf, Laurenz Rettig, Ralph Ernstorfer.
We present our progress in developing the new paradigm of multidimensional photoemission spectroscopy (MPES) to probe quasiparticle wavefunctions. By...
Ultrathin ZnO on Ag(111) has emerged as an interesting material platform for the atomic-scale investigation of light-matter interaction in plasmonic tunnel junctions. As ultrathin layers, ZnO forms a two-dimensional hexagonal lattice with a layer-thickness dependent electronic structure. In addition, an interface state (IS) is formed at the ZnO/Ag(111) interface, whose coupling to the ZnO-CBE...
Hydrogen-bonded (H-bonded) molecular networks are ubiquitous in nature, appearing in systems such as DNA, proteins, and ice, to name a few. Achieving a comprehensive understanding of chemical reactions within these networks requires spatial resolution at the molecular level, which has been particularly challenging for photochemical studies. In this poster, we present our recent investigation...
Inhomogeneous molecular assemblies at interfaces play a critical role in both natural and industrial systems, with examples ranging from lipid rafts in biological membranes to lab-on-a-chip technologies. Investigating these assemblies at the molecular level, particularly their composition, arrangement, and packing structure, is a subject of great scientific interest. However, achieving such...
The air-water interface is one of the most prevalent interfaces on Earth and is central to a vast range of natural and industrial processes. The sheer presence of the interface induces significant changes in its properties such as density and dielectric function, as well as the distribution of molecular orientations and interconnectivity of the H-bond network. The widespread importance of...
Metal-halide perovskites (MHPs) emerged as exciting novel semiconductors with outstanding optoelectronic properties for applications in photovoltaics and light emission. More recently, these semiconductors also attract interest as promising candidates for spintronics. In the absence of inversion symmetry, spin-orbit coupling (SOC) leads to the Rashba-Dresselhaus effect, offering outlook for...
We report on tip-enhanced Raman spectroscopy (TERS) of H$_2$ and D$_2$ molecules physisorbed on Ag(111) at cryogenic temperatures (around 10 K). The intense Raman peaks resulting from the rotational and vibrational transitions are observed at sub-nanometer gap distances of the junction formed by a Ag tip and the Ag surface. Our results suggest that TERS based on low-temperature scanning...
Phonon polaritons are hybrid light-matter particles in solid-state materials that enable waveguiding of light on length scales much smaller than the photon wavelength. Here, we introduce HfSe$_2$ as a new van der Waals material that supports phonon polaritons in the terahertz (THz) spectral range. We image the propagation of these polaritons with a near-field optical microscope that is...
The Kagome lattice offers a plethora of interesting physics ranging from van-Hove singularities to Dirac points and flat bands. In particular, the Kagome metals family AV3Sb5 (A=K, Rb, Cs) features an unconventional superconducting phase, coexisting with a parent charge density wave (CDW) phase. The origin of the CDW is still under debate. Moreover, this family exhibit a flat band below the...
Femtosecond electron diffraction (FED) allows direct observation of a crystal lattice’s response to laser excitation. It is ideally suited to study the ultrafast energy flow from electrons to phonons as well as other photo-induced changes of the lattice, such as structural phase transitions, coherent phonons, and lattice distortions.
We have employed FED to probe lattice dynamics in 2d...
We present an ambient pressure X-ray photoelectron spectroscopy investigation of the adsorption of ammonia on ice over the temperature range of -23 °C to -50 °C. Previous flow tube studies showed significant uptake of ammonia at these temperatures to ice, which was linked to the incorporation of ammonium into the ice crystal lattice. Our present investigation shows a significant uptake of...
As a promising chemical storage medium for hydrogen, the thermal decomposition of ammonia using non-precious metal catalysts, such as Co, Ni, and Fe, has recently gained significant attention. In our work, we are exploring new avenues for the synthesis of such catalysts. We prepare nanostructured oxide precursors that contain both the active element and potential promoters in their crystal...
In the pursuit of carbon neutrality, the catalytic hydrogenation of CO₂ using renewable H₂ is considered a promising route for the production of fuels and chemicals, while its integration with carbon capture and utilization processes (ICCU) provides an alternative and innovative approach for the synthesis of value-added products.¹ Even though the formation of C₁ molecules by CO/CO₂...
CO2 hydrogenation is a kinetically limited reaction, occurring exclusively at the catalyst surface. To achieve satisfactory catalytic conversions, it is essential to form a reactive interface that facilitates the adsorption of CO2 and its subsequent conversion to the desired products, i.e., methanol. The industrially established system for methanol production via CO2 hydrogenation is Cu/ZnO,...
CO2 reduction should minimize hydrogen use while co-producing base chemicals. Plasma pyrolysis generates black carbon along with ethylene and acetylene1. Due to operational hazards, concentrated acetylene must be selectively hydrogenated into valuable ethylene. Pd-based catalysts are commonly used for this reaction. However, the surface and subsurface dynamics of active...
Abstract
Ammonia is industrially produced by the Haber-Bosch process over a fused, multi-promoted iron-based catalyst [1]. Current knowledge about this reaction has been derived from model systems with less structural complexity impeding a clear-cut structure-activity correlation [1,2]. Here, we explore the real structure and its structural evolution of complex, technical,...
Solid oxide cells (SOCs) are highly efficient electrochemical devices that convert electrical energy into chemical fuels, offering a versatile solution for energy storage to mitigate the intermittency of renewable energy sources in modern power systems. Operating at elevated temperatures, typically above 600 °C, SOCs benefit from favorable thermodynamic and kinetic efficiencies. However, these...
In recent years, nickel-oxyhydroxide has come into focus as a low-cost and efficient material in the Oxygen Evolution Reaction (OER) via electrochemical water splitting. It is a prototypical active and stable catalyst for alkaline OER, however, its precise reaction mechanism is not yet fully understood. We coupled pulse voltammetry, operando X-ray absorption spectroscopy (XAS) and density...
Cobalt-based oxides are excellent catalysts for oxidation reactions, both in thermal catalysis1 and in electrocatalysis.2 Here, we present an overview of combined operando X-ray spectroscopic and operando transmission electron microscopic studies of cobalt spinel oxides (Co3O4) and perovksites (LaCoxFe1-xO3) in...
CO₂ electrocatalytic reduction reaction allows to convert environmentally harmful CO₂ into useful chemicals. To this aim, Cu stands out as the only catalyst capable of producing valuable hydrocarbons and alcohols, such as ethylene and ethanol.1-2
The catalyst surface structure plays a key role in determining the selectivity towards certain carbon products; in particular, vicinal...
The electrocatalytic reduction of nitrate (NO3RR) presents a promising approach for decentralized clean ammonia (NH3) production, while simultaneously mitigating environmental pollution caused by toxic and carcinogenic nitrate-laden wastewater.[1] Copper-based materials are attractive NO3RR catalysts due to their affordability and high NH3 selectivity.[2] However, the mismatch in adsorption...
Electrocatalytic water splitting is one of the most promising technologies for producing green hydrogen from renewable resources. However, the anodic oxygen evolution reaction (OER) remains the bottleneck of this process due to its sluggish kinetics. In alkaline water electrolysis, nanocrystalline spinel-type Co3O4 is a highly attractive anode material due to its low...
This study explores the epitaxial growth of cobalt oxide (Co₃O₄) thin films on platinum (Pt(100)) single crystals, focusing on the interfacial phenomena that drive the Oxygen Evolution Reaction (OER) in electrochemical water-splitting.1 By systematically varying film thickness, we uncover the delicate interplay between interfacial charge transfer and surface polarization, both...
Various electrocatalytic reactions are influenced by cationic species in the electrolyte, although their exact role is often debated.1 Resolving the electrochemical interface is thus essential for comprehending the interaction of electrolyte species with electrode surfaces and designing improved catalytic systems. Surface X-ray Diffraction (SXRD) has been shown to be a powerful technique for...
The hydrogen evolution reaction (HER) is the most prominent electrocatalytic reaction. It is needed to generate green hydrogen from water and simultaneously serves as the test reaction for general electrocatalyst function in aqueous media. Despite this, it remains poorly understood. Attempts have been made to describe HER kinetics according to Brønsted-Evans-Polanyi relationships for which the...
The oxygen reduction reaction (ORR) is a key reaction in fuel cells and Li-air batteries. Despite this, the fundamental reaction mechanism is still not understood. Frequently, kinetics are described with Butler-Volmer type theory, assuming that the electric bias is completely translated in reducing the activation enthalpy (activation energy). However, at solid-electrolyte interfaces, the bias...
Electrocatalysts exist within a complex liquid reaction environment and experience (electro)chemical driving force that can change their structural and composition from the as-synthesized state. It is, therefore, crucial that we have insight into the working state of the catalyst if we are to reliably relate the catalyst morphologies with this associated catalytic performance. Even though this...
One of the most important aspects of rational catalyst design is controlling the environment of active sites. In electrocatalysis, the use of organic ligands has emerged as a promising strategy to tune the activity and selectivity of the catalyst. In particular, Arduengo-type N-heterocyclic carbenes (NHCs) and the closely related N-heterocyclic olefins (NHO) have emerged as promising ligands...
Carbon capture and reutilization is a necessity for transitioning towards a sustainable society. Electrocatalytic carbon dioxide reduction reactions (CO2RR) to hydrocarbons at copper cathodes is one promising route, where the selectivity and activity are dictated by a complex interplay of copper oxidation state, structure, and oxygen content at the (sub)surface.[1] Stabilization of these...
Transition metal-nitrogen-doped carbons (TM-N-C) are promising catalysts for several important electrochemical processes, including CO$_{2}$ electrocatalytic reduction (CO$_{2}$RR) [1]. In these catalysts, nitrogen is incorporated into a carbon matrix, creating binding sites for metal species. The latter are believed to be the active sites for CO$_{2}$RR. Among different TM-N-Cs, Ni-N-C is...
Catalysts evolve dynamically under operating conditions. From atomic-scale restructuring to severe coke formation, the dynamic evolution of the catalyst structure is closely linked to changes in catalytic performance. Operando X-ray absorption spectroscopy (XAS) is a well-suited technique to probe the dynamic structural changes under realistic reaction conditions and to correlate rich...
The implementation of single atom catalysts (SACs) critically depends on the stability of single atoms towards sintering. We have recently shown that the catalyst pre-treatment with oxygen plasma improves stability and reactivity of Pt/CeO2 SACs in CO oxidation.1 Here we focused on employing “cold” plasma to SACs for reactions under the reducing (H2 containing) atmosphere. In this work, we...
The hydrogenation of CO$_2$ to methanol occurs with high efficiency on Cu/ZnO-based catalysts. However, the nature of the Cu−Zn interaction and especially the role of Zn in Cu/ZnO catalysts are still not fully understood. In the industrial Cu/ZnO/Al$_2$O$_3$ catalyst, Zn was found to migrate onto the Cu surface during the reaction, thus forming a Cu−ZnO interface that is crucial for a high...
Indium oxide (In2O3) has recently received considerable attention in the catalysis community due to its unexpectedly high selectivity in the hydrogenation of CO2 to methanol.1 Metal deposition onto In2O3 substantially promotes the activity, while the selectivity remains close to that of bare In2O3 independent of the metal used.2,3 To get insight into the metal/In2O3 interaction and the role of...
Copper (Cu) is a leading catalyst for CO$_2$ electroreduction (CO2RR) to multi-carbon products, though its structure sensitivity and stability remain debated. This study reveals that CO2RR does not occur on perfect Cu(111) and Cu(100) surfaces but rather on defect sites, such as steps and kinks [1,2]. Under reaction conditions, these planar surfaces restructure into more active stepped...
CuNi nanoparticles have been successfully employed as catalysts in many chemical reactions. Depending on reaction conditions changes in their surface composition are observed, due to the adsorption of molecules. Here, we studied the Ni/Cu(100) single crystal surface as a model system for CO2 hydrogenation to explore the segregation trends under different reaction atmospheres. Exposure to an...
Methane dry reforming (MDR, CH₄ + CO₂ → 2CO + 2H₂) is a promising pathway to produce syngas while reducing the net emission of two of the most harmful greenhouse gases. The industrially relevant catalyst, Ni, suffers from major drawbacks, such as carbon deposition and sintering at high reaction temperatures1.
One alternative to address these issues is the use of bimetallic catalysts2. The...
The structure of interfacial hydration layers plays a crucial role in energy and chemical conversion processes, impacting the kinetics of electrocatalytic reactions such as CO2 electroreduction (CO2RR) and hydrogen evolution (HER). We reveal the intricate interplay between carbon and proton sources within the microenvironment of bicarbonate electrolytes and highlight the...
