Article
Chemistry, Physical
C. J. Weststrate, Devyani Sharma, Daniel Garcia Rodriguez, Hans O. A. Fredriksson, J. W. Niemantsverdriet
Summary: Understanding the kinetics of oxygen removal from catalytically active metal surfaces by hydrogen is crucial for various catalytic reactions. By studying a Co(0001) single crystal model catalyst, it was found that water formation is first order in surface hydrogen concentration and the order in oxygen concentration changes from one to zero with varying oxygen coverage. In situ XPS analysis revealed that the hydrogen surface concentration saturates at around 10-1 mbar, and a typical temperature of 450 K is sufficient for water formation at high pressures as well. The absence of OH buildup suggests that the rate-limiting step is O + H, with a barrier energy of approximately 120 kJ/mol. This high barrier indicates that slow removal of adsorbed oxygen from reactive metal catalyst surfaces, like cobalt, may limit the overall reaction rate.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Physics, Applied
Matteo Amati, Luca Gregoratti, Patrick Zeller, Mark Greiner, Mattia Scardamaglia, Benjamin Junker, Tamara Russ, Udo Weimar, Nicolae Barsan, Marco Favaro, Abdulaziz Alharbi, Ingvild J. T. Jensen, Ayaz Ali, Branson D. Belle
Summary: Near ambient pressure scanning photoelectron microscopy combines high resolution microscopy with the capability of chemical analysis under high gas pressure conditions, making it valuable for fundamental and applied research such as oxidation reactivity and gas sensitivity.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Peter A. Sharma, Taisuke Ohta, Michael T. Brumbach, Joshua D. Sugar, Joseph Michael
Summary: PEEM was used to investigate the surfaces of textured polycrystalline N-type bismuth telluride and P-type antimony telluride materials, showing changes in work function with exposure to air and the formation of oxide layers. The observed work function contrast is attributed to the pinning of electronic surface states due to defects at grain boundaries.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Review
Chemistry, Physical
Sabine V. Auras, Ludo B. F. Juurlink
Summary: Traditional surface science research focuses on flat surfaces of single crystals, but there has been a growing interest in curved surfaces in recent decades. The application of modern surface sensitive techniques has allowed for new insights into a wide range of surface structures, leading to an increase in research on curved surfaces in surface physics and chemistry.
PROGRESS IN SURFACE SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Vaidish Sumaria, Philippe Sautet
Summary: Step and kink sites on Pt surfaces play a crucial role in determining the adsorption structure of CO under ambient conditions. Both the step structure and the arrangement of CO molecules on the step influence the organization of CO molecules on the lower terrace. Different types of steps lead to diverse adsorption configurations of CO on the terrace.
Article
Chemistry, Physical
Tzu-En Chien, Lea Hohmann, Dan J. Harding
Summary: This study presents a new velocity map imaging instrument for studying molecular beam surface scattering in a near-ambient pressure environment. The instrument allows for the investigation of chemical reaction dynamics and kinetics at higher pressures, bridging the gap between surface science and applied catalysis.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Inorganic & Nuclear
Weihua Ji, Na Wang, Xin Chen, Qiang Li, Kun Lin, Jinxia Deng, Jun Chen, Xianran Xing
Summary: In this study, the behavior and catalytic activity of single-atom Cu catalysts on CeO2 surfaces were investigated. The results showed that CeO2 (100) and (111) surfaces can stabilize active Cu+ species, while Cu exists as Cu2+ on the (110) surface. The most active site for CO adsorption was found to be Cu+, which promotes reaction intermediates formation and reduces reaction energy barriers. Additionally, it was discovered that CO is more likely to activate the subsurface oxygen on the CeO2 (100) surface.
INORGANIC CHEMISTRY
(2022)
Article
Mathematics, Applied
Ludvig Of Klinteberg, Chiara Sorgentone, Anna-Karin Tornberg
Summary: This paper presents a method for estimating quadrature errors in the evaluation of layer potentials defined over smooth curved surfaces. The results are highly accurate, with low computational cost, and can be practically applied.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2022)
Article
Multidisciplinary Sciences
Manjul Sharma, K. Aswathy Nair, R. Vishnu, A. Sameen
Summary: Taylor-Couette flow is used to study Taylor-Gortler (TG) instability and associated vortices. Computational study confirms the presence of TG-like near-wall vortical structures in Vogel-Escudier (VE) and lid-driven cavity (LDC) flows. These vortices are observed in chaotic regimes in both flows, with VE flow transitioning from a steady state and LDC flow exhibiting a limit cycle.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Materials Science, Coatings & Films
Moonjung Jung, Dongwoo Kim, Hojoon Lim, Minsik Seo, Geonhwa Kim, Lucia Perez Ramirez, Fabrice Bournel, Jean-Jacques Gallet, Ki-Jeong Kim, Bongjin Simon Mun
Summary: Using ambient pressure X-ray photoelectron spectroscopy, the surface segregation and oxidation dynamics of platinum-3d transition metal alloys were investigated, revealing the different behaviors of titanium and vanadium atoms on the alloy surface at different temperatures and atmospheres, as well as the formation of different metal oxides during CO oxidation.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2021)
Article
Chemistry, Physical
Ziwen Liu, Lijuan Niu, Xupeng Zong, Li An, Dan Qu, Xiayan Wang, Zaicheng Sun
Summary: The XC-72R supported Pd catalysts exhibit low-temperature catalytic activity for CO oxidation under light irradiation, with a significant performance enhancement attributed to the photothermal effect of carbon.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2022)
Article
Chemistry, Multidisciplinary
Andrey V. Bukhtiyarov, Igor P. Prosvirin, Maxim A. Panafidin, Alexey Yu. Fedorov, Alexander Yu. Klyushin, Axel Knop-Gericke, Yan V. Zubavichus, Valery I. Bukhtiyarov
Summary: This study investigated the catalytic activity of HOPG-supported bimetallic Pd-Au catalysts towards CO oxidation by varying the Pd/Au atomic ratio. The results showed distinct differences in ignition temperatures and activity between catalysts with different initial Pd/Au atomic ratios.
Article
Chemistry, Physical
Tuyet-Mai Tran-Thuy, Teng-Li Yu, Shawn D. Lin
Summary: This study investigates the influence of adsorbed H2O on CO oxidation over Au/BN catalysts. It is found that increasing the calcination temperature results in more Au particles distributed on the BN basal plane, increased water affinity, increased defects on BN, and altered CO oxidation activity. The turnover frequency is found to correlate with H2O physisorption, suggesting the involvement of (H2O)(n,ad) cluster in CO activation.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2022)
Article
Polymer Science
Tesfaldet Mengistu, Richard J. Pazur
Summary: HNBR elastomers with varying acrylonitrile concentrations were subjected to heat aging and analyzed using FTIR, elemental analysis, and liquid proton NMR. The study revealed the development of various functional groups during heat aging, with different regions of oxidative kinetics identified based on carbonyl growth index and T-TS analysis. Activation energies were found to increase with temperature and lower acrylonitrile levels, contributing to enhanced oxidative heat aging resistance.
POLYMER DEGRADATION AND STABILITY
(2021)
Article
Chemistry, Physical
Peng Chai, Hong Xu, Longxia Wu, Haocheng Wang, Cong Fu, Weixin Huang
Summary: This study reported an in situ NAP-XPS investigation of CO activation and hydrogenation on a Co(0001) surface, revealing distinct changes in CO coverage and decomposition under different temperatures and atmospheres. These results contribute to a better understanding of the mechanisms involved in Co-catalyzed FTS reactions.
JOURNAL OF PHYSICAL CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Xiangzhi Meng, Jenny Moeller, Masoud Mansouri, Daniel Sanchez-Portal, Aran Garcia-Lekue, Alexander Weismann, Chao Li, Rainer Herges, Richard Berndt
Summary: Spin-flip excitations of iron porphyrin molecules on Au(111) were investigated using a low-temperature scanning tunneling microscope. The molecules exhibited two distinct adsorption configurations on the surface, with different magnetic anisotropy energies. Density functional theory calculations showed that the different structures and excitation energies were a result of different occupations of the Fe 3d levels. We demonstrated that the magnetic anisotropy energy could be controlled by changing the adsorption site, orientation, or tip-molecule distance.
Article
Chemistry, Physical
Jan Patrick Calupitan, Tao Wang, Alejandro Perez Paz, Berta Alvarez, Alejandro Berdonces-Layunta, Paula Angulo-Portugal, Rodrigo Castrillo-Bodero, Frederik Schiller, Diego Pena, Martina Corso, Dolores Perez, Dimas G. de Oteyza
Summary: This paper reports the activation of a C-C sigma bond at room temperature on Cu(111). A biphenylene derivative's C-C sigma bond is broken, followed by the insertion of Cu from the substrate. The study offers new synthetic routes that can be used for in situ generation of activated species for the on-surface synthesis of novel C-based nanostructures. Overall significance of the article is rated 7.5 out of 10.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Jiayue Wang, Dmitri Kalaev, Jing Yang, Iradwikanari Waluyo, Adrian Hunt, Jerzy T. Sadowski, Harry L. Tuller, Bilge Yildiz
Summary: Exsolution is a recent advancement in fabricating oxide-supported metal nanoparticle catalysts. The kinetics of metal exsolution depends on the kinetics of oxygen release from the host oxide, in addition to the kinetics of metal cation diffusion. This study demonstrates that in the thin-film perovskite SrTi0.65Fe0.35O3 (STF) system, surface oxygen release governs the metal nanoparticle exsolution kinetics. Increasing the oxygen release rate in STF accelerates the Fe0 exsolution kinetics and increases the quantity of exsolved Fe0 over time.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Federico Frezza, Frederik Schiller, Ales Cahlik, Jose Enrique Ortega, Johannes V. Barth, Andres Arnau, Maria Blanco-Rey, Pavel Jelinek, Martina Corso, Ignacio Piquero-Zulaica
Summary: In this study, quinoidal ligands were reacted with single cobalt atoms on an Au(788) surface in ultra-high vacuum, resulting in the formation of cobalt-quinoid chains. The electronic structure of these chains was investigated using angle-resolved photoemission spectroscopy, and their narrow bandgap structure was revealed using low-temperature scanning tunneling microscopy/spectroscopy. Theoretical calculations confirmed that the observed electronic bands originated from the efficient hybridization of cobalt and molecular orbitals. This work provides a foundation for the systematic search of similar one-dimensional π-d hybridized metal-organic chains with tunable electronic and magnetic properties.
Article
Chemistry, Multidisciplinary
R. Castrillo-Bodero, M. Blanco-Rey, K. Ali, J. E. Ortega, F. Schiller, L. Fernandez
Summary: Magnetic hybrid metal-organic interfaces have great potential in areas such as organic spintronics and quantum information processing. However, it is crucial to be able to tune the carrier injection barriers on-demand for technological devices. In this study, we prepared hybrid metal-organic interfaces by adsorbing copper phthalocyanine CuPc on REAu2 surfaces and investigated their growth, electrostatics, and electronic structure. Our results showed that the RE valence of the substrate has a significant effect on the carrier injection barrier of the interface.
Article
Chemistry, Physical
David Degerman, Patrick Lomker, Christopher M. Goodwin, Mikhail Shipilin, Fernando Garcia-Martinez, Christoph Schlueter, Anders Nilsson, Peter Amann
Summary: Operando X-ray photoelectron spectroscopy was used to investigate the surface state of Ni(111) and Ni(211) single crystal surfaces during CO hydrogenation. The results showed that at higher temperatures and hydrogen content, CO moved away from on-top configurations and toward multicoordinated sites on the nickel surface. A nickel carbide was formed in the surface near region, especially at high partial pressures of CO and lower temperatures. The presence of the carbide affected CO bonding, but was reduced during hydrogen-rich conditions and temperatures above 250 degrees C.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Physics, Condensed Matter
Sofia Sanz, Nick Papior, Geza Giedke, Daniel Sanchez-Portal, Mads Brandbyge, Thomas Frederiksen
Summary: We theoretically study electron interference in a Mach-Zehnder-like geometry formed by four parallel pairs of zigzag graphene nanoribbons. By adjusting the interribbon separation, each intersection can function as an electron beam splitter or mirror, allowing for tuneable circuitry with interfering pathways. We evaluate the electron transport properties of these eight-terminal devices and identify pairs of terminals subject to self-interference. The proposed devices have potential applications as magnetic field sensors, detectors of phase shifts induced by local scatterers, and for the study of quantum entanglement.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Chemistry, Multidisciplinary
Haozhe Yang, Maider Ormaza, Zhendong Chi, Eoin Dolan, Josep Ingla-Aynes, C. K. . Safeer, Franz Herling, Nerea Ontoso, Marco Gobbi, Beatriz Martin-Garcia, Frederik Schiller, Luis E. Hueso, Felix Casanova
Summary: The spin Hall effect in graphene can be enhanced by decorating it with a light metal oxide, which overcomes the low spin-orbit coupling and retains a long spin diffusion length. The efficiency of this all-light-element heterostructure can be tuned by the Fermi level position and exhibits a maximum around the charge neutrality point. It shows a higher efficiency compared to conventional spin Hall materials and can be controlled by gate voltage up to room temperature, offering a potential spin-to-charge conversion system free from heavy metals and compatible with large-scale fabrication.
Article
Chemistry, Physical
Sha Tan, Muhammad Mominur Rahman, Zhaohui Wu, Haodong Liu, Shen Wang, Sanjit Ghose, Hui Zhong, Iradwikanari Waluyo, Adrian Hunt, Ping Liu, Xiao-Qing Yang, Enyuan Hu
Summary: Sulfurized polyacrylonitrile (SPAN) has been extensively studied due to its low cost, high capacity, and great reversibility. However, the reaction mechanism of SPAN remains poorly understood. In this study, synchrotron-based pair distribution function (PDF) analysis and soft X-ray absorption spectroscopy (sXAS) were used to investigate the structural and interphasial changes of SPAN. PDF analysis revealed key structural features of SPAN, such as C-S bond, sulfur dimer, and sulfur chain. sXAS showed surface changes of SPAN, including the formation of a negatively charged carbon or fused benzene layer and an electrolyte decomposition layer.
ACS ENERGY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Vahagn Mkhitaryan, Andrew P. Weber, Saad Abdullah, Laura Fernandez, Zakaria M. Abd El-Fattah, Ignacio Piquero-Zulaica, Hitesh Agarwal, Kevin Garcia Diez, Frederik Schiller, J. Enrique Ortega, F. Javier Garcia de Abajo
Summary: This study demonstrates the ability to confine light to atomic scales using atomically thin crystalline silver nanostructures. The fabricated structures allow for unprecedented control over optical field confinement in the near-infrared spectral region, leading to extreme spatial confinement and high-quality plasmon modes.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
David Degerman, Christopher M. Goodwin, Patrick Lomker, Fernando Garcia-Martinez, Mikhail Shipilin, Andrei Gloskovskii, Anders Nilsson
Summary: By rapidly switching from high pressure to low pressure, this method allows for the detection of the remnant high pressure surface and the dynamics during re-equilibration. It provides faster and more detailed spectra compared to static operando measurements. However, there are different explanations for the different adsorbate distributions and the faster accumulation of CHx in CO2 and CO hydrogenation reactions.
Article
Chemistry, Physical
Vikram Mehar, Helen Edstrom, Mikhail Shipilin, Uta Hejral, Chengjun Wu, Aravind Kadiri, Stefano Albertin, Benjamin Hagman, Kim von Allmen, Tim Wiegmann, Sebastian Pfaff, Jakub Drnec, Johan Zetterberg, Edvin Lundgren, Lindsay R. Merte, Johan Gustafson, Jason F. Weaver
Summary: The structures of oxide phases on metallic catalysts during reaction have a strong influence on the catalytic oxidation of CO and CH4. It has been found that an epitaxial PdO(100) structure forms on Pd(100) at temperatures above 600 K during the oxidation process. Additionally, the oxidation behavior of Pd(100) changes from forming epitaxial PdO(101) at 500 K to simultaneously growing epitaxial PdO(100) and PdO(101) at temperatures above 600 K, resulting in a thicker and rougher oxide layer. This change is attributed to a temperature-induced change in the stability of small PdO domains that initiate the oxidation process.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Alaa Mohammed Idris Bakhit, Khadiza Ali, Anna A. Makarova, Igor Pis, Federica Bondino, Roberto Sant, Saroj P. Dash, Rodrigo Castrillo-Bodero, Yuri Hasegawa, J. Enrique Ortega, Laura Fernandez, Frederik Schiller
Summary: This study investigates the structural, electronic, magnetic properties, and chemical stability of a reactive metal, Europium, intercalated between a hexagonal boron nitride (hBN) layer and a Pt substrate. It is found that the intercalation of Europium leads to the formation of a hBN-covered ferromagnetic EuPt2 surface alloy with divalent Eu2+ atoms at the interface. The system is exposed to ambient conditions, and partial conservation of the divalent signal is observed, indicating the stability of the Eu-Pt interface. By using a curved Pt substrate, the changes in the Eu valence state and the protection against ambient pressure at different substrate planes are explored. The formation of the interfacial EuPt2 surface alloy remains consistent, but the resistance of the protective hBN layer to ambient conditions is reduced, likely due to surface roughness and discontinuous hBN coating.
Article
Chemistry, Physical
David Degerman, Patrick Lomker, Christopher M. Goodwin, Mikhail Shipilin, Fernando Garcia-Martinez, Christoph Schlueter, Anders Nilsson, Peter Amann
Summary: The state of the surface near-region during CO hydrogenation of Ni(111) and Ni(211) single crystal surfaces was investigated using operando X-ray photoelectron spectroscopy. Higher temperatures and hydrogen content were found to result in the movement of CO from on-top configurations to multicoordinated sites of the nickel surface and the formation of nickel carbide in the surface near region, particularly at high partial pressures of CO and lower temperatures. The presence of carbide affected CO bonding and the reduction of carbide was observed under hydrogen-rich conditions and temperatures above 250 degrees C.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)