Article
Chemistry, Physical
Volkan Cinar, Audrey Dannar, Adrian Hunt, Alex C. Schilling, Yicheng Wang, Ryan T. Hannagan, Jessica Korotkin, Iradwikanari Waluyo, E. Charles H. Sykes
Summary: Single-atom catalysts, which are supported by oxides, metals, and carbonaceous supports, are a rapidly emerging field in which late-transition metal atoms play a crucial role. These catalysts hold promise for selective chemical reactions due to their well-defined active sites and reduced precious metal loading. However, there are challenges with oxide-supported single-atom catalysts, including deactivation and ongoing debates about the nature of the active sites.
Article
Chemistry, Physical
Xu Li, Keito Horiba, Ryoichi Sugiura, Tomoaki Yamada, Junji Yuhara
Summary: In this study, three different precursor Ba-O films on Pt(1 1 1) were characterized and oxide crystalline approximant (OCA) and oxide quasicrystal (OQC) films were prepared via Ti deposition and annealing. Analysis revealed phase transformation likely follows Ti reduction and Ba oxidation, leading to a change in surface atomic density. Structural models proposed for the OCA and OQC films involve cluster tiling of Ba atoms.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Sebastian Kaiser, Johanna Plansky, Matthias Krinninger, Andrey Shavorskiy, Suyun Zhu, Ueli Heiz, Friedrich Esch, Barbara A. J. Lechner
Summary: Encapsulation via strong metal-support interaction (SMSI) can overcome the sintering problem of metal nanoparticles at elevated temperatures. In this study, Pt5, Pt10, and Pt19 clusters deposited on Fe3O4(001) were encapsulated, and the stability was investigated. The encapsulated clusters could still diffuse as a whole below 823 K, suppressing atom detachment and Ostwald ripening, and resulting in square-shaped crystalline Pt particles.
Article
Chemistry, Multidisciplinary
Yue Sun, Koen Schouteden, Maria Recaman Payo, Jean-Pierre Locquet, Jin Won Seo
Summary: The research demonstrates the growth of insulating two-dimensional vanadium oxide directly on the HOPG surface, suggesting vanadium oxide as a promising candidate for graphene/oxide heterostructures. The obtained oxide layers are polycrystalline with mixed-valence states, mainly V5+ and V4+, and exhibit insulating properties. These findings open up potential applications for graphene-based electronic devices.
Article
Chemistry, Multidisciplinary
Stepan Kovarik, Roberto Robles, Richard Schlitz, Tom Sebastian Seifert, Nicolas Lorente, Pietro Gambardella, Sebastian Stepanow
Summary: In this study, the combination of EPR and STM techniques was used to probe the bonding and charge state of alkali metal atoms on an ultrathin magnesium oxide layer on a silver substrate. The results showed that Li2, LiNa, and Na2 dimers exhibit a +1e charge state and a magnetic moment, while single alkali metal atoms only have a charge state without a magnetic moment. The ionization of the adsorbates is attributed to charge transfer through the oxide to the metal substrate.
Article
Physics, Applied
Tae Soo Kim, Taemin Ahn, Tae-Hwan Kim, Hee Cheul Choi, Han Woong Yeom
Summary: Recent research shows that atomic oxygen can oxidize epitaxial graphene in a vacuum without causing damage. In this study, the effects of chemisorbed atomic oxygen on the electronic properties of graphene were investigated using scanning tunneling microscopy (STM). The results reveal that oxygen atoms can modify the electronic states of graphene, creating a bandgap at its Dirac point. Additionally, it was demonstrated that selective desorption or hopping of oxygen atoms can be induced with atomic precision using appropriate bias sweeps with an STM tip. These findings suggest the potential for atomic-scale tailoring of graphene oxide and the development of graphene-based atomic-scale electronic devices.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Kun Xie, Pengju Li, Liangliang Liu, Runxiao Zhang, Yumin Xia, Haohao Shi, Desheng Cai, Yitong Gu, Limin She, Yeheng Song, Weifeng Zhang, Zhengyu Zhang, Yu Jia, Shengyong Qin
Summary: Researchers have successfully grown two-monolayer highly crystalline Pb1-xBix(111) films with controllable Bi concentrations x using molecular beam epitaxy and studied their structural and superconducting properties using scanning tunneling microscopy. They found that the superconducting transition temperatures of Pb1-xBix films exhibit a domelike behavior with increasing Bi concentration x. First-principles calculations revealed that Bi doping can promote the electronic states and the electron-phonon coupling strength at lower x, but suppress the electron-phonon coupling strength and superconductivity with largely Bi electronic states when Bi doping increases over a critical ratio. These findings not only demonstrate a quantum phenomenon of superconductivity in highly crystalline alloyed films but also provide a practical pathway to tune the superconductivity at the atomic level.
Article
Chemistry, Physical
B. V. Andryushechkin, T. V. Pavlova, V. M. Shevlyuga
Summary: The atomic structure of the Ag(111)-p(4 x 4)-O phase was reexamined and two phases with the same periodicity were discovered. It was demonstrated that the accepted Ag6 model is incompatible with high-resolution oxygen-sensitive STM images.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2024)
Article
Chemistry, Multidisciplinary
Corinna Stumm, Manon Bertram, Maximilian Kastenmeier, Florian D. Speck, Zhaozong Sun, Jonathan Rodriguez-Fernandez, Jeppe Lauritsen, Karl J. J. Mayrhofer, Serhiy Cherevko, Olaf Brummel, Joerg Libuda
Summary: This study investigates the structural dynamics and stability of cobalt oxide on Au(111) under different potentials, revealing different properties and behaviors at various potential ranges.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Gabriela Borin Barin, Qiang Sun, Marco Di Giovannantonio, Cheng-Zhuo Du, Xiao-Ye Wang, Juan Pablo Llinas, Zafer Mutlu, Yuxuan Lin, Jan Wilhelm, Jan Overbeck, Colin Daniels, Michael Lamparski, Hafeesudeen Sahabudeen, Mickael L. Perrin, Jose Urgel, Shantanu Mishra, Amogh Kinikar, Roland Widmer, Samuel Stolz, Max Bommert, Carlo Pignedoli, Xinliang Feng, Michel Calame, Klaus Muellen, Akimitsu Narita, Vincent Meunier, Jeffrey Bokor, Roman Fasel, Pascal Ruffieux
Summary: In this study, the growth, characterization, and device integration of 5-atom wide armchair GNRs were investigated, showing potential for switching behavior at room temperature. The optimized growth protocols successfully bridge between atomic precision control of electronic properties and successful device integration of GNRs.
Article
Chemistry, Physical
Wenxuan Zhang, Xutao Wang, Ningning Liu, Jinyue Wang, Yueqiao Qu, Shiyong Wang, Hao Zheng, Yao-Yi Li, Canhua Liu, Jin-Feng Jia
Summary: Using scanning tunneling microscopy and spectroscopy, the molecular arrangement and electronic structure of C60 ultrathin films grown on a SrTiO3(0 0 1) surface were investigated. The monolayer C60 exhibited a short-range ordered molecular arrangement with disordered molecular orientation and a substantially large HOMO-LUMO gap (-4.1 eV). In contrast, C60 in the 2nd and 3rd layers self-assembled into hexagon lattices with a quasi-(2 x 2) superstructure, resulting in a chiral pinwheel structure.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Rui Li, Jin-Hua Nie, Jing-Jing Xian, Jian-Wang Zhou, Yan Lu, Mao-Peng Miao, Wen-Hao Zhang, Ying-Shuang Fu
Summary: The growth of ultrathin films with molecular beam epitaxy allows for the construction of CrTe3-CrTe2 planar heterojunctions. Vacuum annealing transforms CrTe3 into CrTe2, which can be controlled by annealing time. We also identified a superstructure composed of hybrid units of CrTe3 and CrTe2. This study provides a foundation for building spintronic circuits and engineering electronic states in artificial superlattice structures.
Article
Chemistry, Physical
Miriam Fischer, Mohan Kumar Kuntumalla, Gilad Gani, Alon Hoffman
Summary: The retention and thermal stability of Ar implanted into polycrystalline diamond surfaces with 700 and 5000 eV Ar ions, at high dose (HD) and low dose (LD) of 1016 and 1014 ions/cm2, were investigated at room temperature (RT) and 400 degrees C. It was found that the thermal stability of the retained Ar is higher at 400 degrees C than at RT, with stability exceeding 1000 degrees C. Ar trapped in a high crystalline diamond environment has higher thermal stability than in a graphite/amorphous carbon environment. The desorption of Ar occurs through diffusion between local defects, and is greatly enhanced between 600 and 700 degrees C.
APPLIED SURFACE SCIENCE
(2023)
Article
Nanoscience & Nanotechnology
Xiaolong Liu, Matthew S. Rahn, Qiyuan Ruan, Boris Yakobson, Mark C. Hersam
Summary: This study evaluates the oxidation mechanism of borophene upon exposure to air and molecular oxygen in ultrahigh vacuum (UHV). It finds that borophene degrades rapidly in air but undergoes controlled oxidation in UHV with molecular oxygen. By characterizing the atomic-scale changes and providing insights into the pathways, this study informs the efforts to utilize borophene in ambient conditions.
Article
Nanoscience & Nanotechnology
A. N. Chaika, S. Bozhko, A. M. Ionov, I Sveklo, E. Yu Postnova, V. N. Semenov, A. Bisht, E. Rabkin
Summary: The solid state dewetting of a ten monolayers thick Ag film on periodically patterned Si(557) surface leads to the formation of faceted single crystalline Ag nanoparticles with bimodal size distribution when annealed at temperatures between 300 and 400 degrees C. Some particles contain screw dislocations producing a step on the upper particle facet.
SCRIPTA MATERIALIA
(2021)
Article
Nanoscience & Nanotechnology
Martin Krammer, Alexander Schmid, Andreas Nenning, Andreas Ewald Bumberger, Matthaeus Siebenhofer, Christopher Herzig, Andreas Limbeck, Christoph Rameshan, Markus Kubicek, Juergen Fleig
Summary: Electrochemical impedance spectroscopy was used to investigate the chemical capacitance of LSC thin-film electrodes under anodic polarization. The study found that the chemical capacitance decreased with increasing anodic overpotentials for both dense electrodes and electrodes with open porosity. However, after annealing in synthetic air or applying high anodic bias voltages, extremely high chemical capacitance peaks were observed. These peaks were attributed to the development of closed pores in the electrodes. Model calculations based on a real-gas equation accurately predicted the experimentally obtained capacitance increase. The analysis of chemical capacitance in solid oxide electrolysis cells can serve as a nondestructive tool to detect and quantify closed porosity.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Multidisciplinary Sciences
Giada Franceschi, Pavel Kocan, Andrea Conti, Sebastian Brandstetter, Jan Balajka, Igor Sokolovic, Markus Valtiner, Florian Mittendorfer, Michael Schmid, Martin Setvin, Ulrike Diebold
Summary: This study presents atomic force microscopy images to investigate the distribution of K+ ions on the cleaved mica surface under ultra-high vacuum conditions. The data reveal the presence of short-range ordering and provide insights into the distribution of subsurface Al3+ ions.
NATURE COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Christoph Riedl, Matthaeus Siebenhofer, Andreas Nenning, George E. Wilson, John Kilner, Christoph Rameshan, Andreas Limbeck, Alexander K. Opitz, Markus Kubicek, Juergen Fleig
Summary: The oxygen exchange kinetics of Pr0.1Ce0.9O2-delta electrodes were modified by decorating with submonolayer amounts of binary oxides. The OER rate and total conductivity were measured using i-PLD and changes in electrochemical properties were observed after each pulse of surface decoration. The surface chemistry of the electrodes was investigated using NAP-XPS and LEIS. The results showed that the OER rate was significantly altered by the surface decorations, but the fundamental OER mechanism was not affected.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Verena Pramhaas, Holger Unterhalt, Hans-Joachim Freund, Guenther Rupprechter
Summary: The surface structure and shape of oxide-supported metal nanoparticles can be determined using polarization-dependent sum-frequency-generation (SFG) spectroscopy. This technique reveals the average surface structure and shape of the nanoparticles and can be used to monitor particle restructuring in situ. It has the potential to be a valuable tool for operando catalysis.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Thanaree Phongamwong, Noelia Barrabes, Waleeporn Donphai, Thongthai Witoon, Guenther Rupprechter, Metta Chareonpanich
Summary: Solar-driven photocatalysis is a promising approach for clean production using sunlight as an energy source. The efficiency of nanocrystalline TiO2 catalysts can be improved by functionalizing them with Au-25 clusters, Au nanoparticles, and chlorophyll. The most effective degradation of rhodamine B was achieved using a P25 catalyst functionalized with both Au-25 and chlorophyll. Various characterization techniques were used to investigate the factors influencing the photocatalytic activity.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2023)
Article
Electrochemistry
Lena Puntscher, Kevin Daninger, Michael Schmid, Ulrike Diebold, Gareth S. Parkinson
Summary: Understanding the stability of metal atoms on metal oxide supports is crucial for predicting the stability of single-atom catalysts. In this study, scanning tunnelling microscopy (STM) and x-ray photoelectron spectroscopy (XPS) were used to investigate the stability of platinum, rhodium, nickel, and iridium on the anatase TiO2(101) surface. The study found that introducing defect sites into metal oxide supports can aid the dispersion of single atoms on metal-oxide surfaces, and the presence of water should be taken into account in the modelling of single-atom catalysts.
ELECTROCHIMICA ACTA
(2023)
Article
Chemistry, Physical
Florian Kraushofer, Matthias Meier, Zdenek Jakub, Johanna Huetner, Jan Balajka, Jan Hulva, Michael Schmid, Cesare Franchini, Ulrike Diebold, Gareth S. Parkinson
Summary: This study investigates the (111) facet of magnetite (Fe3O4) and reveals three new surface structures that are more favorable under reducing conditions. The new structures change the coordination of iron atoms to a tetrahedral configuration. Atomically-resolved microscopy confirms the presence of tetrahedral iron atoms capped by 3-fold coordinated oxygen atoms. This discovery explains the inert nature of the reduced patches.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Computer Science, Artificial Intelligence
Marco Corrias, Lorenzo Papa, Igor Sokolovic, Viktor Birschitzky, Alexander Gorfer, Martin Setvin, Michael Schmid, Ulrike Diebold, Michele Reticcioli, Cesare Franchini
Summary: Analyzing atomically resolved images is a time-consuming process that requires expertise and manual intervention. To automate and improve the efficiency of image analysis, machine learning techniques have been applied in scanning probe and electron microscopies. This work introduces a free and open source tool called AiSurf that uses scale-invariant feature transform and clustering algorithms to inspect atomically resolved images. The tool extracts crucial information from the images without pre-assumptions or extensive user intervention, making it a valuable asset for interpreting scanning probe microscopy images.
MACHINE LEARNING-SCIENCE AND TECHNOLOGY
(2023)
Correction
Chemistry, Analytical
Michael Schmid, David Rath, Ulrike Diebold
ACS MEASUREMENT SCIENCE AU
(2023)
Article
Chemistry, Multidisciplinary
Vera Truttmann, Adea Loxha, Rares Banu, Ernst Pittenauer, Sami Malola, Maria Francisca Matus, Yuchen Wang, Elizabeth A. Ploetz, Guenther Rupprechter, Thomas Burgi, Hannu Hakkinen, Christine Aikens, Noelia Barrabes
Summary: Chiral gold nanoclusters were synthesized using the chiral ligand 2-MeBuSH, leading to the unexpected formation of enantiopure chiral clusters. The chiral activity of Au-144 was found to be stronger than Au-38 or Au-25, as confirmed by experimental evaluation using circular dichroism spectroscopy. The prepared chiral clusters exhibited stability against diastereoisomerization up to temperatures of 80°C. These findings demonstrate the selective preparation of enantiopure, intrinsically chiral, and highly stable thiolate-protected Au nanoclusters, supporting the predicted super chirality in the Au-144 cluster.
Article
Engineering, Chemical
Orrakanya Phichairatanaphong, Nevzat Yigit, Guenther Rupprechter, Metta Chareonpanich, Waleeporn Donphai
Summary: Reducing greenhouse gas emissions and utilizing more renewable clean energy through dry reforming reactions are important. The study found that a CeMgZnAl oxide quad-blend-supported Ni catalyst showed outstanding performance and resistance to coking during dry reforming reactions.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Thomas Ruh, Dominic Berkovec, Florian Schrenk, Christoph Rameshan
Summary: Perovskites have great potential for various applications due to their general properties and tunability. Exsolution, the formation of nanoparticles on the surface, is a key feature that has been extensively studied. However, there has been no comprehensive evaluation on the effect of exsolution conditions on the anchorage and morphology of nanoparticles.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Matthaeus Siebenhofer, Andreas Nenning, George E. Wilson, John A. Kilner, Christoph Rameshan, Markus Kubicek, Juergen Fleig, Peter Blaha
Summary: This study investigates the effects of sulphur adsorbates and other SOFC poisons on the electronic and ionic properties of an SrO-terminated LSC surface and its oxygen exchange kinetics. Experimental and computational methods were used to analyze the surface modifications caused by the adsorbates. The results show that sulphur adsorbates strongly deactivate the LSC surface and affect oxygen vacancy formation energies. The study also reveals a correlation between work function changes and redistributed charge with the acidity of the adsorbed oxide.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Physical
Matthaeus Siebenhofer, Christoph Riedl, Andreas Nenning, Werner Artner, Christoph Rameshan, Alexander Karl Opitz, Juergen Fleig, Markus Kubicek
Summary: Minimizing the overpotential at the air electrode of solid oxide fuel cells (SOFC) is crucial for its broader application. Surface modification, including Sr decoration, can alter the oxygen exchange kinetics at SOFC cathode surfaces. However, the mechanism behind this effect is still debated. This study used in situ impedance spectroscopy to investigate the effect of Sr decorations under different deposition conditions and found opposing effects of Sr decoration depending on the deposition temperature and gas phase interactions.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Multidisciplinary Sciences
Maximilian Raab, Johannes Zeininger, Yuri Suchorski, Alexander Genest, Carla Weigl, Guenther Rupprechter
Summary: Promoters play an important role in catalysis, but their function and role in reaction instabilities are often unknown. This study demonstrates the local catalytic effect of La in hydrogen oxidation reaction using Rh nanotip as a mimic of single Rh nanoparticle. The presence of La shifts the reaction states, changes the oscillation pattern, and deactivates one of the pacemaker types. The effect originates from the enhanced oxygen activation on the catalyst.
NATURE COMMUNICATIONS
(2023)