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Carine Michel

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Carine Michel received her PhD in 2007 in Theoretical Chemistry at the Université Joseph Fourier, Grenoble, France, under the supervision of Pr. A. Milet. She focused mainly on modelling the chemical reactivity of various homogeneous systems. Then, she spent one year as a post-doctoral fellow under the supervision of Pr. E.J. Baerends at the VU University, Amsterdam in the field of C-H oxidation.In 2009, she was appointed at the Laboratoire de Chimie as a CNRS researcher to focus on the catalytic valorisation of biomass into chemicals. She extended her research themes to the study of reactive solid/liquid interfaces with a focus on the life cycle of catalysts, from preparation to deactivation. She has long-term collaboration with Solvay and the E2P2 lab in particular in Shanghai, with uOttawa (French PI of the LIA Funcat) and more recently with Total and IFPEN.She received the Bronze medal of the CNRS (2015).

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Papers by Carine Michel

Facile soft-chemistry synthesis of Co-Ru nanoalloys: influence of the composition on the catalytic activity for the acceptorless dehydrogenation of alcohols

The synthesis of Co-Ru bimetallic nanoparticles was performed by co-reduction of Co(II) and Ru(II... more The synthesis of Co-Ru bimetallic nanoparticles was performed by co-reduction of Co(II) and Ru(III) salts in octan-1-ol, acting both as a solvent and a mild reducing agent. The metal composition was varied in the entire range, from pure Co to pure Ru. Although Co and Ru are miscible in the bulk, the formation of nanoalloys is not straightforward and requires selecting carefully reaction parameters such as the nature of the solvent and that of the metal precursors. The formation of nanoalloys was unambiguously evidenced by HAADF STEM–EDX analyses. The particle size and the size dispersity were found to decrease with increasing Ru amount, yielding very small and monodisperse particles for the richest compositions in Ru. The unsupported particles were tested for the acceptorless alcohol dehydrogenation using (±)-octan-2-ol and octan-1-ol as model substrates. The results clearly show a synergetic effect since the bimetallic particles exhibit better performances than their monometallic c...

Influence of Capping Ligands on the Catalytic Performances of Cobalt Nanoparticles Prepared with the Organometallic Route

The Journal of Physical Chemistry C, 2021

Cobalt nanorods and cobalt nanoplatelets, prepared by the same organometallic route with two diff... more Cobalt nanorods and cobalt nanoplatelets, prepared by the same organometallic route with two different metal precursors, were tested for the first time in the acceptor-less dehydrogenation of 2-octanol. The nature of the metal precursor determines not only nanoparticle morphology but also their surface chemistry. While cobalt nanorods showed high conversions (up to 85% after 24 h) and complete selectivity toward 2-octanone with concomitant molecular hydrogen production, cobalt nanoplatelets were practically inactive. Here, we show that this striking difference in the catalytic properties is not associated with facet-dependent differences in reactivity, but rather with different surface chemistry. The activity critically depends on the coordinating ability of the adsorbed species under catalytic reaction conditions and to a smaller degree on their concentration, as evidenced by ligand exchange experiments at room temperature as well as by direct addition of ligands in the reaction during catalysis by cobalt nanorods. This study shows that to optimize performances with unsupported metal nanocatalysts, the capping ligands should be selected by considering their ability to reversibly dissociate from the metal surface during catalysis.

Etudes théoriques de la Catalyse

à leur manière à accompagner, encadrer, guider sur le chemin de la Recherche. J'essaie à mon tour... more à leur manière à accompagner, encadrer, guider sur le chemin de la Recherche. J'essaie à mon tour d'être une "bonne chef" et c'est un apprentissage de chaque jour! Merci à tous pour votre confiance et surtout. .. votre patience! Le travail de recherche ne peut se faire sans le groupe de Chimie Théorique, membres passés et présents, le Laboratoire et tous ceux en "soutien à la recherche", du pôle de gestion aux informaticiens, du Laboratoire de Chimie aux services de l'ENS de Lyon et du CNRS, merci à tous pour votre soutien! Pour finir, mon infinie reconnaissance à mes proches, amis, famille.

(Dis)Similarities of adsorption of diverse functional groups over alumina and hematite depending on the surface state

The Journal of Chemical Physics, 2021

To accelerate the conversion to more sustainable lubricants, there is a need for an improved unde... more To accelerate the conversion to more sustainable lubricants, there is a need for an improved understanding of the adsorption at the solid/liquid interface. As a first step, the DFT computed adsorption energies can be used to screen the ability of additives to cover a surface. Analogously to what has been found in catalysis with the universal scaling relations, we investigate here if a general universal ranking of additives can be found, independently of the surface considered. We divided our set of 25 diverse representative molecules into aprotic and protic molecules. We compared their adsorption over alumina and hematite, which are models of surface oxidized aluminum and steel, respectively. The adsorption energy ranking of our set is not strongly affected by alumina hydration. In contrast, adsorption on hematite is more strongly affected by hydration since all exposed Fe Lewis acid sites are converted into hydroxylated Brønsted basic sites. However, the ranking obtained on hydrated hematite is close to the one obtained on dry alumina, paving the road to a fast screening of additives. In our library, protic molecules are more strongly adsorbed than non-protic molecules. In particular, methyl and dimethyl phosphates are the most strongly adsorbed ones, followed by Nmethyldiethanolamine, succinimide and ethanoic acid. Additives combining these functional groups are expected to strongly adsorb at the solid/liquid interface and, therefore, likely to be relevant components of lubricant formulations.

Hydroxide-Induced Degradation of Olefin Metathesis Catalysts: A Challenge for Metathesis in Alkaline Media

ACS Catalysis, 2020

Hydroxide ion is shown to be a potent disruptor of Ru-catalyzed olefin metathesis, in a study of ... more Hydroxide ion is shown to be a potent disruptor of Ru-catalyzed olefin metathesis, in a study of the Hoveyda catalyst HII. Addition of [N n Bu4][OH] immediately terminates metathesis via HII, an effect traced to formation of bis(hydroxide) complex HII-OH. The latter was synthesized for direct study. HII-OH initiates very slowly on reaction with olefins, and decomposes in the first cycle of metathesis. Computational analysis reveals rapid bimolecular coupling between HII-OH and its four-coordinate methylidene derivative. Importantly, fully decomposed catalyst also accelerates decomposition of HII-OH. The H-bonding capacity of the hydroxide ligand is proposed as a powerful driving force for decomposition.

AuCu/CeO2 bimetallic catalysts for the selective oxidation of fatty alcohol ethoxylates to alkyl ether carboxylic acids

Journal of Catalysis, 2019

We describe in this work the preparation of a series of bimetallic Au-Cu catalysts supported over... more We describe in this work the preparation of a series of bimetallic Au-Cu catalysts supported over nanoceria for the direct oxidation of C 12-C 14-alcohol polyethyleneglycol ether with on average 7 ethyl oxide units (AEO7) to polyoxyethylene lauryl ether carboxylic acid (AECA6), using H 2 O 2 as an oxidant, under basic conditions. Different preparation methods have been used, including deposition-precipitation, incipient wetness impregnation and wet impregnation for engineering the interaction between Au, Cu and nanoceria. The structure of the bimetallic catalysts is discussed in detail on the basis of a refined characterization by XRD, HR-TEM, STEM-EDX-SDD, XPS and ICP-AES. The formation of a AuCu alloy over nanoceria at a Cu/Au molar ratio of 0.11 on Au allows a significant enhancement of the catalytic activity, resulting in an AECA6 yield up to 80% with a selectivity of 90%. The catalyst can be recycled and reused for at least 10 consecutive runs without apparent loss of activity. Detailed DFT calculations on Au, Cu and Au-Cu model alloys reveal a positive role of Cu on Au by favoring the adsorption of AEO7, H 2 O 2 and OHon the catalyst surface compared to pure Au, as well as by reducing the energy barrier for H 2 O 2 cleavage. Isolated Cu sites on the Au-Cu alloy appear as crucial for enhancing the catalytic properties for AEO7 oxidation.

DockOnSurf: A Python Code for the High-Throughput Screening of Flexible Molecules Adsorbed on Surfaces

Journal of Chemical Information and Modeling, 2021

We present the open-source python package DockOnSurf which automates the generation and optimizat... more We present the open-source python package DockOnSurf which automates the generation and optimization of low-energy adsorption configurations of molecules on extended surfaces and nanoparticles. DockOnSurf is especially geared towards handling polyfunctional flexible adsorbates. The use of this high-throughput workflow allows to carry out the screening of adsorbate-surface configurations in a systematic, customizable and traceable way, while keeping the focus on the chemically relevant structures. The screening strategy consists on splitting the exploration of the adsorbate-surface configurational space into chemically meaningful domains, i.e., by choosing among different conformers to adsorb, surface adsorption sites, adsorbate anchoring points, orientations and allowing dissociation of (acidic) protons. We demonstrate the performance of the main features based on varying examples, ranging from CO adsorption on a gold nanoparticle to sorbitol adsorption on hematite. Through the use of the presented program, we aim to foster efficiency, traceability and ease of use in research within tribology, catalysis, nanoscience and surface science in general.

DFT investigations for the catalytic reaction mechanism of methane combustion occurring on Pd(ii)/Al-MCM-41

Physical Chemistry Chemical Physics, 2018

A theoretical analysis was carried out on the mechanism of methane combustion occurring on the si... more

Adhesion of lubricant on aluminium through adsorption of additive head-groups on γ-alumina: A DFT study

Tribology International, 2019

To improve lubricant formulation, a better understanding of the wettability properties and hence ... more To improve lubricant formulation, a better understanding of the wettability properties and hence of the interactions between the surface and the lubricant additives is a key parameter. Herein, we use density functional theory calculations to characterize 32 typical head groups, classified into four categories: protic, aprotic, aromatic and phosphorus-containing molecules. By comparing their adsorption energies on γ-alumina, used as a surface model of aluminium sheets, and their solvation energies in a model lubricant base oil, we found that the solvation energy was not a discriminant parameter while the adsorption energy was critical. Phosphates and carboxylic acids are the most strongly adsorbed, and thus more likely to yield to improved wettability properties of the lubricant through film formation.

Theoretical insight into the origin of the electrochemical promotion of ethylene oxidation on ruthenium oxide

Catalysis Science & Technology, 2019

In EPOC the adsorption energies of the reactants and products are modified by applying an electro... more

Rational design of selective metal catalysts for alcohol amination with ammonia

Nature Catalysis, 2019

The lack of selectivity for the direct amination of alcohols with ammonia, a modern and clean rou... more The lack of selectivity for the direct amination of alcohols with ammonia, a modern and clean route for the synthesis of primary amines, is an unsolved challenge. Here, we combine first-principles calculations, scaling relations, kinetic simulations and catalysis experiments to unveil the key factors governing the activity and selectivity of metal catalysts for this reaction. We show that the loss of selectivity towards primary amines is linked to a surface-mediated C-N bond coupling between two N-containing intermediates: CH 3 NH and CH 2 NH. The barrier for this step is low enough to compete with the main surface hydrogenation reactions and can be used as a descriptor for selectivity. The combination of activity and selectivity maps using the C and O adsorption energies as descriptors is used for the computational screening of 348 dilute bimetallic catalysts. Among the best theoretical candidates, Co 98.5 Ag 1.5 and Co 98.5 Ru 1.5 (5 wt% Co) are identified as the most promising catalysts from experiments.

Key Role of Anionic Doping for H2 Production from Formic Acid on Pd(111)

ACS Catalysis, 2017

Hydrogen evolution by the catalytic decomposition of formic acid in solution is a key reaction fo... more Hydrogen evolution by the catalytic decomposition of formic acid in solution is a key reaction for hydrogen storage for which palladium is one of the most efficient catalysts. Based on DFT computations, we explain why the presence of an anionic promoter renders palladium more active and more selective for formic acid dehydrogenation. The promotion is well captured by modelling the anion by a negatively charged surface. This promotional effect can be traced back to the modulation of the electric field at the catalyst surface, with a strongly contrasted action on the energy of the various species along the competing pathways through the electrostatic interaction between the electric field and the surface dipole moment. As a result, both the reaction kinetics and selectivity are markedly improved. This opens the door to a rational design of catalytic systems using promoters.

Study of a Novel Hepta-coordinated FeIII Bimetallic Complex with an Unusual 1,2,4,5-Tetrazine-Ring Opening

Polyhedron, 2016

Abstract Reaction of Fe(NO3)3 with 3,6-di(pyrimidin-2-yl)-1,2,4,5-tetrazine (BPymTz) in acetonitr... more Abstract Reaction of Fe(NO3)3 with 3,6-di(pyrimidin-2-yl)-1,2,4,5-tetrazine (BPymTz) in acetonitrile gives a hepta-coordinated FeIII complex (1) with the bridging unit 1,2-diiminohydrazido (1,2-dih2−: −HN C(R) N N C(R) NH−) generated in situ from the tetrazine ring-opening of BPymTz. DFT calculations, X-ray diffraction studies and SQUID magnetometry measurements were successfully performed on 1. The crystallography measurement confirms the ring-opening and the substituent’s contribution to the rare pentagonal bipyramidal coordination geometry of the metal ions. Magnetic susceptibility measurements on 1 reveal an S = 0 ground state, arising from the antiferromagnetic interaction between the two FeIII centers (J = −3.02 cm−1) within the molecule.

Why Is Ruthenium an Efficient Catalyst for the Aqueous-Phase Hydrogenation of Biosourced Carbonyl Compounds?

ACS Catalysis, 2015

Role of water in metal catalyst performance for ketone hydrogenation: a joint experimental and theoretical study on levulinic acid conversion into gamma-valerolactone

Chemical communications (Cambridge, England), Jan 25, 2014

While Ru is a poor hydrogenation catalyst compared to Pt or Pd in the gas phase, it is efficient ... more While Ru is a poor hydrogenation catalyst compared to Pt or Pd in the gas phase, it is efficient under aqueous phase conditions in the hydrogenation of ketones such as the conversion of levulinic acid into gamma-valerolactone. Combining DFT calculations and experiments, we demonstrate that water is responsible for the enhanced reactivity of Ru under those conditions.

In Silico Screening of Iron-Oxo Catalysts for CH Bond Cleavage

ACS Catalysis, 2015

Inspired by oxidation enzymes such as P450 and TauD, several groups have based their research on ... more Inspired by oxidation enzymes such as P450 and TauD, several groups have based their research on the iron–oxo moiety in the field of alkanes partial oxidation. Still, the controlled cleavage and oxidation of the aliphatic C–H bond remains a prized goal in chemistry. We present here a computational methodology to predict the comparative reactivity of iron–oxo complexes for this process from linear relations based on the sole electronic structure of the reactant state. The efficient correlation of the C–H activation barrier to a simple but intuitive molecular orbital descriptor enables the design of ligands that permit low barrier C–H abstraction steps and the fast screening of novel potential complexes. The activation of the catalyst by a multidentate effect is also evidenced. We anticipate this study to improve the rational design of hydrocarbon oxidation catalysts.

Demystifying the Atomistic Origin of the Electric Field Effect on Methane Oxidation

Understanding the role of an electric field on the surface of a catalyst is crucial in tuning and... more Understanding the role of an electric field on the surface of a catalyst is crucial in tuning and promoting the catalytic activity of metals. Herein, we evaluate the oxidation of methane over a Pt surface with varying oxygen coverage using density functional theory. The latter is controlled CH 4 2 O 2 CO 2 2 H 2 O

Identification of active catalysts for the acceptorless dehydrogenation of alcohols to carbonyls

Nature Communications

Acceptorless dehydrogenation into carbonyls and molecular hydrogen is an attractive strategy to v... more Acceptorless dehydrogenation into carbonyls and molecular hydrogen is an attractive strategy to valorize (biobased) alcohols. Using 2-octanol dehydrogenation as benchmark reaction in a continuous reactor, a library of metal-supported catalysts is tested to validate the predictive level of catalytic activity for combined DFT and micro-kinetic modeling. Based on a series of transition metals, scaling relations are determined as a function of two descriptors, i.e. the surface binding energies of atomic carbon and oxygen. Then, a volcano-shape relation based on both descriptors is derived, paving the way to further optimization of active catalysts. Evaluation of 294 diluted alloys but also a series of carbides and nitrides with the volcano map identified 12 promising candidates with potentially improved activity for alcohol dehydrogenation, which provides useful guidance for experimental catalyst design. Further screening identifies β-Mo2N and γ-Mo2N exposing mostly (001) and (100) face...

Title Computationally Exploring Confinement Effects in the Methane-to-Methanol Conversion Over Iron-Oxo Centers in Zeolites Permalink

Transitionmetal-oxo centers in zeolites are known to be active in the conversion of methane to me... more Transitionmetal-oxo centers in zeolites are known to be active in the conversion of methane to methanol. Here we study this reaction over Fe-oxo sites in the zeolite SSZ-13. By comparing calculations for the fully periodic structure and a cluster for two different methods, the standard van der Waals corrected semi-local density functional PBE-D2 and ACFDT-RPA, a method where correlation is calculated fully non-locally, we find that it is actually the confining environment in the zeolite that reduces the barrier for this reaction by more than 50 % and that the two applied methods lead to qualitatively different results.

Mechanistic investigation and free energies of the reactive adsorption of ethanol at the alumina/water interface

Controlling the adsorption/desorption of molecules at the solid/water interface is central to a d... more Controlling the adsorption/desorption of molecules at the solid/water interface is central to a diversity of fields from catalysis to batteries. Preventing the desorption of alcohol at the gamma-Al2O3/water interface is key to increase the stability of this catalyst support to perform reactions in water. Taking ethanol as a typical example, we investigate here the mechanism of desorption of two adsorption modes, namely chemisorbed ethanol and ethoxy, from the interface to the bulk water using three DFT-based simulations. Our 3D well-tempered metadynamics simulations include a bias in solvation, which triggers possible proton transfers with water. They evidence that solvation needs to be increased prior to desorption in both cases. Comparison with static approaches and thermodynamic integration simulations unambiguously identifies ethoxy as the more stable adsorption mode. It is more stable by at least 40 kJ/mol when considering adsorption at the gas/solid interface. And the presence...

Facile soft-chemistry synthesis of Co-Ru nanoalloys: influence of the composition on the catalytic activity for the acceptorless dehydrogenation of alcohols

The synthesis of Co-Ru bimetallic nanoparticles was performed by co-reduction of Co(II) and Ru(II... more The synthesis of Co-Ru bimetallic nanoparticles was performed by co-reduction of Co(II) and Ru(III) salts in octan-1-ol, acting both as a solvent and a mild reducing agent. The metal composition was varied in the entire range, from pure Co to pure Ru. Although Co and Ru are miscible in the bulk, the formation of nanoalloys is not straightforward and requires selecting carefully reaction parameters such as the nature of the solvent and that of the metal precursors. The formation of nanoalloys was unambiguously evidenced by HAADF STEM–EDX analyses. The particle size and the size dispersity were found to decrease with increasing Ru amount, yielding very small and monodisperse particles for the richest compositions in Ru. The unsupported particles were tested for the acceptorless alcohol dehydrogenation using (±)-octan-2-ol and octan-1-ol as model substrates. The results clearly show a synergetic effect since the bimetallic particles exhibit better performances than their monometallic c...

Influence of Capping Ligands on the Catalytic Performances of Cobalt Nanoparticles Prepared with the Organometallic Route

The Journal of Physical Chemistry C, 2021

Cobalt nanorods and cobalt nanoplatelets, prepared by the same organometallic route with two diff... more Cobalt nanorods and cobalt nanoplatelets, prepared by the same organometallic route with two different metal precursors, were tested for the first time in the acceptor-less dehydrogenation of 2-octanol. The nature of the metal precursor determines not only nanoparticle morphology but also their surface chemistry. While cobalt nanorods showed high conversions (up to 85% after 24 h) and complete selectivity toward 2-octanone with concomitant molecular hydrogen production, cobalt nanoplatelets were practically inactive. Here, we show that this striking difference in the catalytic properties is not associated with facet-dependent differences in reactivity, but rather with different surface chemistry. The activity critically depends on the coordinating ability of the adsorbed species under catalytic reaction conditions and to a smaller degree on their concentration, as evidenced by ligand exchange experiments at room temperature as well as by direct addition of ligands in the reaction during catalysis by cobalt nanorods. This study shows that to optimize performances with unsupported metal nanocatalysts, the capping ligands should be selected by considering their ability to reversibly dissociate from the metal surface during catalysis.

Etudes théoriques de la Catalyse

à leur manière à accompagner, encadrer, guider sur le chemin de la Recherche. J'essaie à mon tour... more à leur manière à accompagner, encadrer, guider sur le chemin de la Recherche. J'essaie à mon tour d'être une "bonne chef" et c'est un apprentissage de chaque jour! Merci à tous pour votre confiance et surtout. .. votre patience! Le travail de recherche ne peut se faire sans le groupe de Chimie Théorique, membres passés et présents, le Laboratoire et tous ceux en "soutien à la recherche", du pôle de gestion aux informaticiens, du Laboratoire de Chimie aux services de l'ENS de Lyon et du CNRS, merci à tous pour votre soutien! Pour finir, mon infinie reconnaissance à mes proches, amis, famille.

(Dis)Similarities of adsorption of diverse functional groups over alumina and hematite depending on the surface state

The Journal of Chemical Physics, 2021

To accelerate the conversion to more sustainable lubricants, there is a need for an improved unde... more To accelerate the conversion to more sustainable lubricants, there is a need for an improved understanding of the adsorption at the solid/liquid interface. As a first step, the DFT computed adsorption energies can be used to screen the ability of additives to cover a surface. Analogously to what has been found in catalysis with the universal scaling relations, we investigate here if a general universal ranking of additives can be found, independently of the surface considered. We divided our set of 25 diverse representative molecules into aprotic and protic molecules. We compared their adsorption over alumina and hematite, which are models of surface oxidized aluminum and steel, respectively. The adsorption energy ranking of our set is not strongly affected by alumina hydration. In contrast, adsorption on hematite is more strongly affected by hydration since all exposed Fe Lewis acid sites are converted into hydroxylated Brønsted basic sites. However, the ranking obtained on hydrated hematite is close to the one obtained on dry alumina, paving the road to a fast screening of additives. In our library, protic molecules are more strongly adsorbed than non-protic molecules. In particular, methyl and dimethyl phosphates are the most strongly adsorbed ones, followed by Nmethyldiethanolamine, succinimide and ethanoic acid. Additives combining these functional groups are expected to strongly adsorb at the solid/liquid interface and, therefore, likely to be relevant components of lubricant formulations.

Hydroxide-Induced Degradation of Olefin Metathesis Catalysts: A Challenge for Metathesis in Alkaline Media

ACS Catalysis, 2020

Hydroxide ion is shown to be a potent disruptor of Ru-catalyzed olefin metathesis, in a study of ... more Hydroxide ion is shown to be a potent disruptor of Ru-catalyzed olefin metathesis, in a study of the Hoveyda catalyst HII. Addition of [N n Bu4][OH] immediately terminates metathesis via HII, an effect traced to formation of bis(hydroxide) complex HII-OH. The latter was synthesized for direct study. HII-OH initiates very slowly on reaction with olefins, and decomposes in the first cycle of metathesis. Computational analysis reveals rapid bimolecular coupling between HII-OH and its four-coordinate methylidene derivative. Importantly, fully decomposed catalyst also accelerates decomposition of HII-OH. The H-bonding capacity of the hydroxide ligand is proposed as a powerful driving force for decomposition.

AuCu/CeO2 bimetallic catalysts for the selective oxidation of fatty alcohol ethoxylates to alkyl ether carboxylic acids

Journal of Catalysis, 2019

We describe in this work the preparation of a series of bimetallic Au-Cu catalysts supported over... more We describe in this work the preparation of a series of bimetallic Au-Cu catalysts supported over nanoceria for the direct oxidation of C 12-C 14-alcohol polyethyleneglycol ether with on average 7 ethyl oxide units (AEO7) to polyoxyethylene lauryl ether carboxylic acid (AECA6), using H 2 O 2 as an oxidant, under basic conditions. Different preparation methods have been used, including deposition-precipitation, incipient wetness impregnation and wet impregnation for engineering the interaction between Au, Cu and nanoceria. The structure of the bimetallic catalysts is discussed in detail on the basis of a refined characterization by XRD, HR-TEM, STEM-EDX-SDD, XPS and ICP-AES. The formation of a AuCu alloy over nanoceria at a Cu/Au molar ratio of 0.11 on Au allows a significant enhancement of the catalytic activity, resulting in an AECA6 yield up to 80% with a selectivity of 90%. The catalyst can be recycled and reused for at least 10 consecutive runs without apparent loss of activity. Detailed DFT calculations on Au, Cu and Au-Cu model alloys reveal a positive role of Cu on Au by favoring the adsorption of AEO7, H 2 O 2 and OHon the catalyst surface compared to pure Au, as well as by reducing the energy barrier for H 2 O 2 cleavage. Isolated Cu sites on the Au-Cu alloy appear as crucial for enhancing the catalytic properties for AEO7 oxidation.

DockOnSurf: A Python Code for the High-Throughput Screening of Flexible Molecules Adsorbed on Surfaces

Journal of Chemical Information and Modeling, 2021

We present the open-source python package DockOnSurf which automates the generation and optimizat... more We present the open-source python package DockOnSurf which automates the generation and optimization of low-energy adsorption configurations of molecules on extended surfaces and nanoparticles. DockOnSurf is especially geared towards handling polyfunctional flexible adsorbates. The use of this high-throughput workflow allows to carry out the screening of adsorbate-surface configurations in a systematic, customizable and traceable way, while keeping the focus on the chemically relevant structures. The screening strategy consists on splitting the exploration of the adsorbate-surface configurational space into chemically meaningful domains, i.e., by choosing among different conformers to adsorb, surface adsorption sites, adsorbate anchoring points, orientations and allowing dissociation of (acidic) protons. We demonstrate the performance of the main features based on varying examples, ranging from CO adsorption on a gold nanoparticle to sorbitol adsorption on hematite. Through the use of the presented program, we aim to foster efficiency, traceability and ease of use in research within tribology, catalysis, nanoscience and surface science in general.

DFT investigations for the catalytic reaction mechanism of methane combustion occurring on Pd(ii)/Al-MCM-41

Physical Chemistry Chemical Physics, 2018

A theoretical analysis was carried out on the mechanism of methane combustion occurring on the si... more

Adhesion of lubricant on aluminium through adsorption of additive head-groups on γ-alumina: A DFT study

Tribology International, 2019

To improve lubricant formulation, a better understanding of the wettability properties and hence ... more To improve lubricant formulation, a better understanding of the wettability properties and hence of the interactions between the surface and the lubricant additives is a key parameter. Herein, we use density functional theory calculations to characterize 32 typical head groups, classified into four categories: protic, aprotic, aromatic and phosphorus-containing molecules. By comparing their adsorption energies on γ-alumina, used as a surface model of aluminium sheets, and their solvation energies in a model lubricant base oil, we found that the solvation energy was not a discriminant parameter while the adsorption energy was critical. Phosphates and carboxylic acids are the most strongly adsorbed, and thus more likely to yield to improved wettability properties of the lubricant through film formation.

Theoretical insight into the origin of the electrochemical promotion of ethylene oxidation on ruthenium oxide

Catalysis Science & Technology, 2019

In EPOC the adsorption energies of the reactants and products are modified by applying an electro... more

Rational design of selective metal catalysts for alcohol amination with ammonia

Nature Catalysis, 2019

The lack of selectivity for the direct amination of alcohols with ammonia, a modern and clean rou... more The lack of selectivity for the direct amination of alcohols with ammonia, a modern and clean route for the synthesis of primary amines, is an unsolved challenge. Here, we combine first-principles calculations, scaling relations, kinetic simulations and catalysis experiments to unveil the key factors governing the activity and selectivity of metal catalysts for this reaction. We show that the loss of selectivity towards primary amines is linked to a surface-mediated C-N bond coupling between two N-containing intermediates: CH 3 NH and CH 2 NH. The barrier for this step is low enough to compete with the main surface hydrogenation reactions and can be used as a descriptor for selectivity. The combination of activity and selectivity maps using the C and O adsorption energies as descriptors is used for the computational screening of 348 dilute bimetallic catalysts. Among the best theoretical candidates, Co 98.5 Ag 1.5 and Co 98.5 Ru 1.5 (5 wt% Co) are identified as the most promising catalysts from experiments.

Key Role of Anionic Doping for H2 Production from Formic Acid on Pd(111)

ACS Catalysis, 2017

Hydrogen evolution by the catalytic decomposition of formic acid in solution is a key reaction fo... more Hydrogen evolution by the catalytic decomposition of formic acid in solution is a key reaction for hydrogen storage for which palladium is one of the most efficient catalysts. Based on DFT computations, we explain why the presence of an anionic promoter renders palladium more active and more selective for formic acid dehydrogenation. The promotion is well captured by modelling the anion by a negatively charged surface. This promotional effect can be traced back to the modulation of the electric field at the catalyst surface, with a strongly contrasted action on the energy of the various species along the competing pathways through the electrostatic interaction between the electric field and the surface dipole moment. As a result, both the reaction kinetics and selectivity are markedly improved. This opens the door to a rational design of catalytic systems using promoters.

Study of a Novel Hepta-coordinated FeIII Bimetallic Complex with an Unusual 1,2,4,5-Tetrazine-Ring Opening

Polyhedron, 2016

Abstract Reaction of Fe(NO3)3 with 3,6-di(pyrimidin-2-yl)-1,2,4,5-tetrazine (BPymTz) in acetonitr... more Abstract Reaction of Fe(NO3)3 with 3,6-di(pyrimidin-2-yl)-1,2,4,5-tetrazine (BPymTz) in acetonitrile gives a hepta-coordinated FeIII complex (1) with the bridging unit 1,2-diiminohydrazido (1,2-dih2−: −HN C(R) N N C(R) NH−) generated in situ from the tetrazine ring-opening of BPymTz. DFT calculations, X-ray diffraction studies and SQUID magnetometry measurements were successfully performed on 1. The crystallography measurement confirms the ring-opening and the substituent’s contribution to the rare pentagonal bipyramidal coordination geometry of the metal ions. Magnetic susceptibility measurements on 1 reveal an S = 0 ground state, arising from the antiferromagnetic interaction between the two FeIII centers (J = −3.02 cm−1) within the molecule.

Why Is Ruthenium an Efficient Catalyst for the Aqueous-Phase Hydrogenation of Biosourced Carbonyl Compounds?

ACS Catalysis, 2015

Role of water in metal catalyst performance for ketone hydrogenation: a joint experimental and theoretical study on levulinic acid conversion into gamma-valerolactone

Chemical communications (Cambridge, England), Jan 25, 2014

While Ru is a poor hydrogenation catalyst compared to Pt or Pd in the gas phase, it is efficient ... more While Ru is a poor hydrogenation catalyst compared to Pt or Pd in the gas phase, it is efficient under aqueous phase conditions in the hydrogenation of ketones such as the conversion of levulinic acid into gamma-valerolactone. Combining DFT calculations and experiments, we demonstrate that water is responsible for the enhanced reactivity of Ru under those conditions.

In Silico Screening of Iron-Oxo Catalysts for CH Bond Cleavage

ACS Catalysis, 2015

Inspired by oxidation enzymes such as P450 and TauD, several groups have based their research on ... more Inspired by oxidation enzymes such as P450 and TauD, several groups have based their research on the iron–oxo moiety in the field of alkanes partial oxidation. Still, the controlled cleavage and oxidation of the aliphatic C–H bond remains a prized goal in chemistry. We present here a computational methodology to predict the comparative reactivity of iron–oxo complexes for this process from linear relations based on the sole electronic structure of the reactant state. The efficient correlation of the C–H activation barrier to a simple but intuitive molecular orbital descriptor enables the design of ligands that permit low barrier C–H abstraction steps and the fast screening of novel potential complexes. The activation of the catalyst by a multidentate effect is also evidenced. We anticipate this study to improve the rational design of hydrocarbon oxidation catalysts.

Demystifying the Atomistic Origin of the Electric Field Effect on Methane Oxidation

Understanding the role of an electric field on the surface of a catalyst is crucial in tuning and... more Understanding the role of an electric field on the surface of a catalyst is crucial in tuning and promoting the catalytic activity of metals. Herein, we evaluate the oxidation of methane over a Pt surface with varying oxygen coverage using density functional theory. The latter is controlled CH 4 2 O 2 CO 2 2 H 2 O

Identification of active catalysts for the acceptorless dehydrogenation of alcohols to carbonyls

Nature Communications

Acceptorless dehydrogenation into carbonyls and molecular hydrogen is an attractive strategy to v... more Acceptorless dehydrogenation into carbonyls and molecular hydrogen is an attractive strategy to valorize (biobased) alcohols. Using 2-octanol dehydrogenation as benchmark reaction in a continuous reactor, a library of metal-supported catalysts is tested to validate the predictive level of catalytic activity for combined DFT and micro-kinetic modeling. Based on a series of transition metals, scaling relations are determined as a function of two descriptors, i.e. the surface binding energies of atomic carbon and oxygen. Then, a volcano-shape relation based on both descriptors is derived, paving the way to further optimization of active catalysts. Evaluation of 294 diluted alloys but also a series of carbides and nitrides with the volcano map identified 12 promising candidates with potentially improved activity for alcohol dehydrogenation, which provides useful guidance for experimental catalyst design. Further screening identifies β-Mo2N and γ-Mo2N exposing mostly (001) and (100) face...

Title Computationally Exploring Confinement Effects in the Methane-to-Methanol Conversion Over Iron-Oxo Centers in Zeolites Permalink

Transitionmetal-oxo centers in zeolites are known to be active in the conversion of methane to me... more Transitionmetal-oxo centers in zeolites are known to be active in the conversion of methane to methanol. Here we study this reaction over Fe-oxo sites in the zeolite SSZ-13. By comparing calculations for the fully periodic structure and a cluster for two different methods, the standard van der Waals corrected semi-local density functional PBE-D2 and ACFDT-RPA, a method where correlation is calculated fully non-locally, we find that it is actually the confining environment in the zeolite that reduces the barrier for this reaction by more than 50 % and that the two applied methods lead to qualitatively different results.

Mechanistic investigation and free energies of the reactive adsorption of ethanol at the alumina/water interface

Controlling the adsorption/desorption of molecules at the solid/water interface is central to a d... more Controlling the adsorption/desorption of molecules at the solid/water interface is central to a diversity of fields from catalysis to batteries. Preventing the desorption of alcohol at the gamma-Al2O3/water interface is key to increase the stability of this catalyst support to perform reactions in water. Taking ethanol as a typical example, we investigate here the mechanism of desorption of two adsorption modes, namely chemisorbed ethanol and ethoxy, from the interface to the bulk water using three DFT-based simulations. Our 3D well-tempered metadynamics simulations include a bias in solvation, which triggers possible proton transfers with water. They evidence that solvation needs to be increased prior to desorption in both cases. Comparison with static approaches and thermodynamic integration simulations unambiguously identifies ethoxy as the more stable adsorption mode. It is more stable by at least 40 kJ/mol when considering adsorption at the gas/solid interface. And the presence...