Article
Chemistry, Multidisciplinary
Lukas Hormann, Andreas Jeindl, Oliver T. Hofmann
Summary: Virtually all organic (opto)electronic devices rely on organic/inorganic interfaces with specific properties. A study found that a change in interface structure can introduce a shift in function. Researchers achieved this by using tetrachloropyrazine on Pt(111), which created switchable interface structures with significantly different adsorption geometries. These structures facilitated different work function changes and coherent fractions, making them ideal for reading out the interface state. The possibility of reversible switching between different classes of structures was demonstrated, creating a dynamic interface for potential applications in organic electronics.
Article
Chemistry, Applied
Simuck F. Yuk, Mal-Soon Lee, Sneha A. Akhade, Manh-Thuong Nguyen, Vassiliki-Alexandra Glezakou, Roger Rousseau
Summary: Understanding the hydrogenation of organic compounds in the aqueous phase is crucial for carbon neutral pathways. This study investigated the thermodynamic and kinetic profiles of benzaldehyde hydrogenation over Pd(111) and Pt(111) metal surfaces. The presence of surface charge and solvent greatly influenced the reaction.
Article
Chemistry, Physical
Jie Wei, Zheng-da He, Wei Chen, Yan-Xia Chen, Elizabeth Santos, Wolfgang Schmickler
Summary: The activity of Pt(111) electrodes for the hydrogen evolution reaction in 0.5M H2SO4 solution increases with continuous potential cycling. Changes in cyclic voltammograms after the hydrogen evolution reaction show a decrease in current waves for hydrogen and sulfate adsorption, possibly due to absorption of a small amount of hydrogen in the subsurface layer.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Griffin Ruehl, S. Elizabeth Harman, Liney Arnadottir, Charles T. Campbell
Summary: The study measured the heat of adsorption of acetonitrile on Pt(111) surface as a function of coverage, revealing a difference in adsorption heats at different temperatures and their impact on saturation coverage. The estimated adhesion energy for liquid acetonitrile on Pt(111) was found to be lower than water, benzene, and phenol, but higher than methanol and formic acid. This information can be useful in estimating the effect of acetonitrile as a solvent on the adsorption energies of catalytic reactants compared to gas phase.
Article
Chemistry, Physical
August E. G. Mikkelsen, Henrik H. Kristoffersen, Jakob Schiotz, Tejs Vegge, Heine A. Hansen, Karsten W. Jacobsen
Summary: In this study, molecular dynamics simulations with an ensemble of neural network potentials were used to investigate the structure and energetics of liquid water and hydroxyl species on Pt(111) surfaces. The results revealed a gradual increase in differential adsorption energy at high hydroxyl coverages, which was explained by the reduction in hydrogen bonds between the water molecules and hydroxyls.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Daniel Arribas, Victor Villalobos-Vilda, Ezequiel Tosi, Paolo Lacovig, Alessandro Baraldi, Luca Bignardi, Silvano Lizzit, Jose Ignacio Martinez, Pedro Luis de Andres, Alejandro Gutierrez, Jose Angel Martin-Gago, Pablo Merino
Summary: In this study, the thermal dehydrogenation of n-octane on Pt(111) was characterized using synchrotron-radiation X-ray photoelectron spectroscopy, temperature-programmed desorption, scanning tunneling microscopy, and ab initio calculations. The results showed two different dehydrogenation stages at low activation temperatures. At 330 K, n-octane underwent a regioselective single C-H bond cleavage at one methyl end. At 600 K, chemisorbed molecules underwent a double dehydrogenation, forming double bonds in their carbon skeletons. Diffusion of the dehydrogenated species resulted in the formation of carbon molecular clusters, which was the first step towards poisoning of the catalyst. These findings reveal the chemical mechanisms of alkane dehydrogenation on platinum surfaces at the atomic scale, providing insights for the design of more efficient dehydrogenation catalysts.
Article
Chemistry, Multidisciplinary
Dmitriy Borodin, Oihana Galparsoro, Igor Rahinov, Jan Fingerhut, Michael Schwarzer, Stefan Horandl, Daniel J. Auerbach, Alexander Kandratsenka, Dirk Schwarzer, Theofanis N. Kitsopoulos, Alec M. Wodtke
Summary: This study presents a detailed kinetics analysis of NH3 thermal desorption rates from p(2 x 2) O/Pt(111). It is found that the adsorption of O-atoms on Pt(111) greatly reduces the desorption rate of NH3. A physical model is proposed to explain the interactions between adsorbed NH3 and O-atoms, and the model is fitted to derive the desorption rate constants. The results indicate a higher stabilization and rotational barrier for NH3 on p(2 x 2) O/Pt(111) compared to Pt(111). The study also highlights the importance of dispersion interactions for accurately predicting the NH3-O adsorbate-adsorbate interactions and NH3 binding energies.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Electrochemistry
Matias A. Villalba, Marc T. M. Koper
Summary: In this paper, the electrocatalytic reduction of methyl vinyl ketone on Pt(111) and Pd-modified Pt(111) electrodes was studied. The selectivity and efficiency of the reaction were calculated, while the adsorbates involved in the deactivation process were analyzed. The research found that Pd-modified Pt(111) electrode was highly active for the selective electrochemical hydrogenation of C=C, while Pt(111) was less active.
ELECTROCHIMICA ACTA
(2022)
Article
Chemistry, Physical
Cheng Bi, Yong Yang
Summary: This study investigates the dynamics of H atoms on a Pt(111) surface using the transfer matrix method and first-principles calculations, demonstrating atomic resonant tunneling phenomenon. It is shown that the rate of H transfer across surface potential fields is significantly reduced due to quantum tunneling effects, decreasing monotonically with temperature within a certain region. The research indicates the nontrivial activities of H-involved reactions at cryogenic conditions, revealing the existence of a nonzero low-temperature limit of rate constant for barrier-crossing processes.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Haochang Deng, Yongli Huang, Jibiao Li
Summary: For a long time, the frontier orbital principle has dominated our understanding of water-metal bonding, where stable interactions are governed by the interaction between highest occupied molecular orbital (HOMO) and metal surfaces. However, using density functional theory calculations, we have discovered that this principle does not apply to metastable water bonding on Pt(111), where HOMO-1 plays a decisive role instead of HOMO. In metastable configurations, there is a delicate competition or balance between sigma (σ)-like orbital interactions exerted by HOMO-1 and pi (π)-like orbital interactions exerted by HOMO. These findings have significantly deepened our understanding of orbital roles in water-metal bonding interactions and bridged the gap between theoretical understanding of electrolyzed water at electrochemical interfaces and water science on metal surfaces.
Article
Crystallography
Guocai Tian, Huanhuan Du, Hongmei Zhang
Summary: The reactivity and adsorption behavior of three pyridine amide additives on the Pt(111) surface were studied using first principle calculations. The additives form stable protective films on the Pt surface, inhibiting dendrite formation and resulting in a smooth aluminum deposition layer.
Article
Chemistry, Physical
Marvin C. Schmidt, Smadar Attia, Carsten Schroeder, Ann-Katrin Baumann, Swetlana Schauermann
Summary: A mechanistic study on the formation and distribution of acetophenone dimers on the Pt(111) surface with different H coverages was conducted. The study found that at high coverage, acetyl/phenyl dimers were prevalent, while at low coverage, ketone-enol dimers prevailed. This indicates a critical dependence of the dimer formation on the surface coverage of H species.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Physical
Kaline Nascimento da Silva, Elton Sitta
Summary: This study observed and mapped for the first time the oscillatory methanol electrooxidation reaction on Pt(111) in non-adsorbing anion solutions and in the presence of small amounts of sulfate anions. The presence of sulfate strongly inhibits the reaction, possibly due to sulfate adlayer formation on {111} domains.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Ding-Yuan Kuo, Xinyao Lu, Bintao Hu, Hector D. Abruna, Jin Suntivich
Summary: The formation of surface-bound hydrogen is significantly faster in acid compared to base, with a reaction-order analysis indicating a standard proton-coupled electron transfer reaction in acid and a pH-independent rate constant in base, suggesting a chemical step involving the reorganization of interfacial water.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Physics, Multidisciplinary
Sudarsan Surendralal, Mira Todorova, Joerg Neugebauer
Summary: The density functional theory molecular dynamics simulations show that coadsorption of H2O has a significant impact on the electrode potential and stability of H adsorbates under electrochemical conditions. These insights explain the observed upper limit of H coverage and propose a chemically intuitive model for metal-water bonding that accounts for a large interaction between coadsorbed water and adsorbates.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Condensed Matter
Soren A. Meldgaard, Henrik L. Mortensen, Mathias S. Jorgensen, Bjork Hammer
JOURNAL OF PHYSICS-CONDENSED MATTER
(2020)
Article
Chemistry, Physical
Mads-Peter V. Christiansen, Henrik Lund Mortensen, Soren Ager Meldgaard, Bjork Hammer
JOURNAL OF CHEMICAL PHYSICS
(2020)
Article
Chemistry, Multidisciplinary
Lindsay R. Merte, Malthe Kjoer Bisbo, Igor Sokolovic, Martin Setvin, Benjamin Hagman, Mikhail Shipilin, Michael Schmid, Ulrike Diebold, Edvin Lundgren, Bjork Hammer
Summary: This study demonstrates the use of an evolutionary algorithm and machine learning methods to solve the unknown surface structure of a (4x4) surface oxide on Pt3Sn(111). The algorithm is efficient and robust, providing a broader application in surface studies.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Astronomy & Astrophysics
Zeyuan Tang, Frederik Doktor S. Simonsen, Rijutha Jaganathan, Julianna Palotas, Jos Oomens, Liv Hornekaer, Bjork Hammer
Summary: Through experimental and theoretical investigations, a chemical pathway of ethylene formation from the fragmentation of superhydrogenated PAHs is proposed, highlighting the sensitivity of this pathway to hydrogenated edges (e.g., the degree of hydrogenation and the hydrogenated positions).
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Chemistry, Physical
Zeyuan Tang, Bjork Hammer
Summary: The dimerization of polycyclic aromatic hydrocarbons (PAHs) is essential in the synthesis of graphene, formation of soot, and growth of carbonaceous dust grains in the interstellar medium. This study presents a cost-effective method using an evolutionary algorithm and machine learning surrogate potentials to investigate the chemical dimerization of dehydrogenated PAHs on graphene surfaces.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Elin Granaes, Ulrike A. Schroeder, Mohammad A. Arman, Mie Andersen, Timm Gerber, Karina Schulte, Jesper N. Andersen, Thomas Michely, Bjork Hammer, Jan Knudsen
Summary: This study investigates room temperature oxygen hydrogenation below graphene flakes supported by Ir(111). The research shows that the graphene cover and its doping level can be used to trap and characterize dense mixed O-OH-H2O phases. The response of these phases to oxygen or hydrogen exposure reveals that additional oxygen can be dissolved into them at room temperature, while additional hydrogen exposure converts the mixed O-OH-H2O phases back to pure OH-H2O.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Mads-Peter V. Christiansen, Nikolaj Ronne, Bjork Hammer
Summary: Modeling and understanding material properties from first principles requires knowledge of atomistic structure. The rise of machine learning techniques in materials science has accelerated structure searches. This paper introduces the customizable Atomistic Global Optimization X (AGOX) framework and code for efficient building and testing of global optimization algorithms.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Nikolaj Ronne, Mads-Peter V. Christiansen, Andreas Moller Slavensky, Zeyuan Tang, Florian Brix, Mikkel Elkjaer Pedersen, Malthe Kjaer Bisbo, Bjork Hammer
Summary: This research describes a local surrogate model used in conjunction with global structure search methods. The model is based on the Gaussian approximation potential formalism and utilizes a smooth overlap of atomic positions descriptor with sparsification. The model demonstrates robustness for a wide range of atomistic systems, highlighting the benefits of a local surrogate model in structure search.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Magnus Klove, Sanna Sommer, Bo B. Iversen, Bjork Hammer, Wilke Dononelli
Summary: A machine learning model incorporating density functional theory calculations and comparison of PDFs can be used to determine the crystal structure of unknown compounds, allowing for the identification of metastable configurations and stacking disorders.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Lindsay R. Merte, Nicolas Braud, Lars Buss, Malthe Kjaer Bisbo, Harald J. Wallander, Jon -Olaf Krisponeit, Jan Ingo Flege, Bjork Hammer, Jens Falta, Edvin Lundgren
Summary: The high performance of platinum-tin catalysts in oxidation reactions is attributed to the formation of tin oxides at the metal surface. However, little is known about the structure of these oxides and their catalytic properties. In this study, we demonstrate that surface oxides on Pt3Sn(111) incorporate oxygen at the metal interface, which can be removed by reaction with CO. This oxygen storage mechanism is enabled by the asymmetrical coordination state of Sn2+.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Andreas Moller Slavensky, Mads-Peter V. Christiansen, Bjork Hammer
Summary: Global optimization of atomistic structure requires generating new candidate structures to explore the potential energy surface (PES) for the global minimum energy structure. This study focuses on locally optimizing structures in complementary energy (CE) landscapes, which are temporarily formulated as machine learned potentials (MLPs) using sampled local atomistic environments. The CE landscapes are intentionally incomplete MLPs, aiming to be smoother with only a few local minima, to facilitate the identification of new funnels in the true PES. The construction and influence of these CE landscapes are discussed, and a new global minimum energy structure is reported for a reduced rutile SnO2(110)-(4 x 1) surface and an olivine (Mg2SiO4)(4) cluster.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Kraen C. Adamsen, Nikolay G. Petrik, Wilke Dononelli, Greg A. Kimmel, Tao Xu, Zheshen Li, Lutz Lammich, Bjork Hammer, Jeppe V. Lauritsen, Stefan Wendt
Summary: The interaction between water and metal oxide surfaces is crucial in various research fields and applications, especially reducible anatase TiO2. This study combines experiments and theory to investigate the dissociation of water on bulk-reduced a-TiO2(101). The results show that after water exposure, point-like protrusions appear on the a-TiO2(101) surface, which originate from hydroxyl pairs (OHt/OHb). The study also provides a comprehensive model of the water/a-TiO2(101) interaction and explains the thermal stability of the hydroxyl pairs up to 480 K.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Malthe K. Bisbo, Bjork Hammer
Summary: GOFEE is an evolutionary algorithm that utilizes machine learning and Bayesian statistics to identify low-energy structures efficiently across computationally expensive energy landscapes. The method employs a Gaussian process regression surrogate model with a Gaussian kernel of two length scales for enhanced performance, while ensuring structural diversity through a sampling scheme and clustering algorithm.
Article
Computer Science, Artificial Intelligence
Soren Ager Meldgaard, Jonas Koehler, Henrik Lund Mortensen, Mads-Peter Christiansen, Frank Noe, Bjork Hammer
Summary: This study proposes a reinforcement learning approach for generating molecules in chemical space and predicting their stability using quantum chemistry. By combining imitation learning and reinforcement learning, the sample efficiency is improved, and low energy molecules are generated under different stoichiometries conditions.
MACHINE LEARNING-SCIENCE AND TECHNOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Albert Bruix, Jeppe V. Lauritsen, Bjork Hammer
Summary: This study investigated the impact of metal surface interactions on the stability and properties of MoS2 nanoparticles, revealing general support-effects on nanoparticle structures. It was found that the choice of supporting metal can modify the properties of nanostructured transition metal dichalcogenides, suggesting a way to tailor the properties of these materials.
