Michael Hävecker
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View article: Local solid-state processes adjust the selectivity in catalytic oxidation reactions on cobalt oxides
Local solid-state processes adjust the selectivity in catalytic oxidation reactions on cobalt oxides Open
Transition metal oxides are excellent catalysts for selective oxidation reactions, which are a prominent source of industrially relevant chemicals. However, these reactions suffer from multiple competing reaction pathways, limiting the sel…
View article: Realizing Scalable Chemical Vapour Deposition of Monolayer Graphene Films on Iron with Concurrent Surface Hardening by in situ Observations
Realizing Scalable Chemical Vapour Deposition of Monolayer Graphene Films on Iron with Concurrent Surface Hardening by in situ Observations Open
Graphene has been suggested as an ultimately thin functional coating for metallurgical alloys such as steels. However, even on pure iron (Fe), the parent phase of steels, growth of high quality graphene films remains largely elusive to dat…
View article: Structural Analysis and Redox Properties of Oxygen-“Breathing” A(Mn<sub>1–<i>x</i></sub>Cu<sub><i>x</i></sub>)O<sub>3</sub> (A = La, Pr) Perovskites
Structural Analysis and Redox Properties of Oxygen-“Breathing” A(Mn<sub>1–<i>x</i></sub>Cu<sub><i>x</i></sub>)O<sub>3</sub> (A = La, Pr) Perovskites Open
The redox properties of perovskites play an important role in their use in thermo- and electrocatalytic applications. Here, we report the effects of substituting copper for manganese in A(Mn1–xCux)O3 (A = La, Pr; 0 ≤ x ≤ 0.4) perovskites o…
View article: Metastable nickel–oxygen species modulate rate oscillations during dry reforming of methane
Metastable nickel–oxygen species modulate rate oscillations during dry reforming of methane Open
When a heterogeneous catalyst is active, it forms metastable structures that constantly transform into each other. These structures contribute differently to the catalytic function. Here we show the role of different metastable oxygen spec…
View article: Thermal synthesis of electron deficient oxygen species on crystalline IrO<sub>2</sub>
Thermal synthesis of electron deficient oxygen species on crystalline IrO<sub>2</sub> Open
μ 2 -O species shown to be active in OER can be thermally produced on crystalline IrO 2 bound to Ir IV+ δ without requiring the presence of Ir III , which offers a route to higher-performance stable OER catalysts.
View article: The Influence of Melting on Catalysis in Propane Oxidation
The Influence of Melting on Catalysis in Propane Oxidation Open
A model catalyst composed of crystalline potassium pentavanadate (K 3 V 5 O 14 ) supported on silica was studied to elucidate the effect of phase transitions on the performance of potassium‐promoted vanadia catalysts in propane oxidation. …
View article: Assessment of the Degradation Mechanisms of Cu Electrodes during the CO<sub>2</sub> Reduction Reaction
Assessment of the Degradation Mechanisms of Cu Electrodes during the CO<sub>2</sub> Reduction Reaction Open
Catalyst degradation and product selectivity changes are two of the key challenges in the electrochemical reduction of CO2 on copper electrodes. Yet, these aspects are often overlooked. Here, we combine in situ X-ray spectroscopy, in situ …
View article: Adjusting the Chemical Reactivity of Oxygen for Propylene Epoxidation on Silver by Rational Design: The Use of an Oxyanion and Cl
Adjusting the Chemical Reactivity of Oxygen for Propylene Epoxidation on Silver by Rational Design: The Use of an Oxyanion and Cl Open
The development of catalysts for propylene oxide production from direct epoxidation using propylene and oxygen remains a challenge. Compared to ethylene epoxidation, where selectivity on silver catalysts is high, the low selectivity to pro…
View article: Data-Centric Heterogeneous Catalysis: Identifying Rules and Materials Genes of Alkane Selective Oxidation
Data-Centric Heterogeneous Catalysis: Identifying Rules and Materials Genes of Alkane Selective Oxidation Open
Artificial intelligence (AI) can accelerate catalyst design by identifying key physicochemical descriptive parameters correlated with the underlying processes triggering, favoring, or hindering the performance. In analogy to genes in biolo…
View article: In situ genesis of selective adsorption sites by complex catalytic redox dynamics
In situ genesis of selective adsorption sites by complex catalytic redox dynamics Open
Several in situ studies have revealed spatiotemporal dynamics on heterogeneous catalysts surfaces under chemical stimuli1-4, which presumably control the activity, selectivity, and productivity5-11. However, operando validations of suffici…
View article: Data-centric heterogeneous catalysis: identifying rules and materials genes of alkane selective oxidation
Data-centric heterogeneous catalysis: identifying rules and materials genes of alkane selective oxidation Open
Artificial intelligence (AI) can accelerate materials design by identifying the key parameters correlated with the performance. However, widely used AI methods require big data, and only the smallest part of the available data in heterogen…
View article: Dynamics over a Cu–graphite electrode during the gas-phase CO<sub>2</sub> reduction investigated by APXPS
Dynamics over a Cu–graphite electrode during the gas-phase CO<sub>2</sub> reduction investigated by APXPS Open
We use ambient pressure X-ray photoelectron and absorption spectroscopies coupled with on-line gas detection to investigate in situ performance and interface chemistry of an electrodeposited Cu on a carbon support under conditions of CO 2 …
View article: The rise of electrochemical NAPXPS operated in the soft X-ray regime exemplified by the oxygen evolution reaction on IrO<sub><i>x</i></sub> electrocatalysts
The rise of electrochemical NAPXPS operated in the soft X-ray regime exemplified by the oxygen evolution reaction on IrO<sub><i>x</i></sub> electrocatalysts Open
Different operando approaches based in PES were used and compared under OER conditions on IrO x . ResPES indicates that single coordinated oxygen atoms (μ 1 -O) are the active species yielding the formation of peroxo (μ 1 -OO) and finally …
View article: Dynamics at Polarized Carbon Dioxide–Iron Oxyhydroxide Interfaces Unveil the Origin of Multicarbon Product Formation
Dynamics at Polarized Carbon Dioxide–Iron Oxyhydroxide Interfaces Unveil the Origin of Multicarbon Product Formation Open
Surface-sensitive ambient pressure X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy combined with an electrocatalytic reactivity study, multilength-scale electron microscopy, and theoretical model…
View article: The Influence of the Chemical Potential on Defects and Function of Perovskites in Catalysis
The Influence of the Chemical Potential on Defects and Function of Perovskites in Catalysis Open
A Sm-deficient Sm 0.96 MnO 3 perovskite was prepared on a gram scale to investigate the influence of the chemical potential of the gas phase on the defect concentration, the oxidation states of the metals and the nature of the oxygen speci…
View article: Surface Electron-Hole Rich Species Active in the Electrocatalytic Water Oxidation
Surface Electron-Hole Rich Species Active in the Electrocatalytic Water Oxidation Open
Iridium and ruthenium and their oxides/hydroxides are the best candidates for the oxygen evolution reaction under harsh acidic conditions owing to the low overpotentials observed for Ru- and Ir-based anodes and the high corrosion resistanc…
View article: Materials Genes of Heterogeneous Catalysis from Clean Experiments and Artificial Intelligence
Materials Genes of Heterogeneous Catalysis from Clean Experiments and Artificial Intelligence Open
Heterogeneous catalysis is an example of a complex materials function, governed by an intricate interplay of several processes, e.g., the different surface chemical reactions, and the dynamic re-structuring of the catalyst material at reac…
View article: Materials Genes of Heterogeneous Catalysis from Clean Experiments and Artificial Intelligence
Materials Genes of Heterogeneous Catalysis from Clean Experiments and Artificial Intelligence Open
Heterogeneous catalysis is an example of a complex materials function, governed by an intricate interplay of several processes, e.g., the different surface chemical reactions, and the dynamic re-structuring of the catalyst material at reac…
View article: Materials genes of heterogeneous catalysis from clean experiments and artificial intelligence
Materials genes of heterogeneous catalysis from clean experiments and artificial intelligence Open
Heterogeneous catalysis is an example of a complex materials function, governed by an intricate interplay of several processes, e.g., the different surface chemical reactions, and the dynamic re-structuring of the catalyst material at reac…
View article: Surface constrained electron-hole rich species active in the electrocatalytic water splitting
Surface constrained electron-hole rich species active in the electrocatalytic water splitting Open
Iridium and its oxides/hydroxides are the best candidates for the oxygen evolution reaction under harsh acidic conditions owing to the low overpotential and the high corrosion resistance observed for Ir-based anodes. Herein, by means of cu…
View article: A comparative study of electrochemical cells for <i>in situ</i> x-ray spectroscopies in the soft and tender x-ray range
A comparative study of electrochemical cells for <i>in situ</i> x-ray spectroscopies in the soft and tender x-ray range Open
In situ x-ray spectroscopies offer a powerful way to understand the electronic structure of the electrode–electrolyte interface under operating conditions. However, most x-ray techniques require vacuum, making it necessary to design spectr…
View article: Towards Experimental Handbooks in Catalysis
Towards Experimental Handbooks in Catalysis Open
The “Seven Pillars” of oxidation catalysis proposed by Robert K. Grasselli represent an early example of phenomenological descriptors in the field of heterogeneous catalysis. Major advances in the theoretical description of catalytic react…
View article: Carbide-Modified Pd on ZrO2 as Active Phase for CO2-Reforming of Methane—A Model Phase Boundary Approach
Carbide-Modified Pd on ZrO2 as Active Phase for CO2-Reforming of Methane—A Model Phase Boundary Approach Open
Starting from subsurface Zr0-doped “inverse” Pd and bulk-intermetallic Pd0Zr0 model catalyst precursors, we investigated the dry reforming reaction of methane (DRM) using synchrotron-based near ambient pressure in-situ X-ray photoelectron …
View article: Graphene-Capped Liquid Thin Films for Electrochemical Operando X-ray Spectroscopy and Scanning Electron Microscopy
Graphene-Capped Liquid Thin Films for Electrochemical Operando X-ray Spectroscopy and Scanning Electron Microscopy Open
Electrochemistry is a promising building block for the global transition to a sustainable energy market. Particularly the electroreduction of CO2 and the electrolysis of water might be strategic elements for chemical energy conversion. The…
View article: Surface Conditions That Constrain Alkane Oxidation on Perovskites
Surface Conditions That Constrain Alkane Oxidation on Perovskites Open
The crystal structure of perovskites can incorporate a wide variety of cations, which makes this class of materials so interesting for studies of links between solid-state chemistry and catalysis. Perovskites are known as typical total com…
View article: Electronic and Dielectric Properties of MoV-Oxide (M1 Phase) under Alkane Oxidation Conditions
Electronic and Dielectric Properties of MoV-Oxide (M1 Phase) under Alkane Oxidation Conditions Open
Isostructural orthorhombic oxides of the general formula (Mo,V,Te,Sb,Nb,Ta)Ox are an important class of solids, which are interesting as catalysts for oxidation of light alkanes. We investigated relations between the electronic properties …