High-Pressure Scanning Tunneling Microscopy

Salmerón, Miquel; Eren, Baran

doi:10.1021/acs.chemrev.0c00429

Cited by 36 publications

(18 citation statements)

References 227 publications

(794 reference statements)

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“…According to the Gibbs–Helmholtz relation, a numerical pressure gap of approximately 13 orders of magnitude can cause a discrepancy in surface free energy of at least +0.3 eV . It means that the increased chemical potential energy is able to cause unintended surface reconstruction, depending on the site-specific atomic-scale strain or the number of surface defects at ambient pressure …”

Section: Introduction To Operando Surface Chemistry On Model Catalyst...mentioning

confidence: 99%

“…13 It means that the increased chemical potential energy is able to cause unintended surface reconstruction, depending on the site-specific atomic-scale strain or the number of surface defects at ambient pressure. 14 A classic example of CO poisoning phenomenon causes the evolution of Pt nanoclusters on the stepped Pt surface above 0.1 mbar CO, 15,16 whereas pressure-induced surface roughening is not observed in the CO pressure range from 10 −7 to 500 mbar on the wide Pt terrace. 17 As the result, this surface restructuring at a local surface not only invokes the atomicscale site-dependent chemisorption but also changes unusual types of the interfacial structure.…”

Section: Introduction To Operando Surface Chemistry On Model Catalyst...mentioning

confidence: 99%

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Operando Surface Studies on Metal-Oxide Interfaces of Bimetal and Mixed Catalysts

et al. 2021

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The formation of metal-oxide interfaces in catalytic systems exhibits a synergistic phenomenon between metal and reducible oxides, often referred to as the strong metal−support interaction (SMSI). This unusual characteristic has been connected to the origin of highly enhanced catalytic performance for decades, but the mechanistic explanation of SMSI remains a long-standing issue in heterogeneous catalysis. To understand this matter at the molecular level, geometric and electronic functions of metal-oxide interfaces during catalytic reactions should be clearly interpreted using advanced microscopic and spectroscopic analysis techniques. In this Review, we highlight recently performed investigations at metal-oxide interfaces by operando characterization tools to identify active sites in working conditions. We introduce two kinds of catalysts, platinum-based bimetallic alloys and mixed metal-oxide catalysts. Selected operando techniques reveal their atomic-scale morphology, surface electronic structure, and charge transfer/transport at surfaces under oxidation, reduction, and gas mixture environments. With bimetallic model catalysts, topographic morphology observations present critical evidence for the structural modulation between the topmost layer and the subsurface lattice in oxygen conditions. For the mixed metal-oxide catalysts, we note that metal nanoparticles on reducible oxides demonstrate the catalytic activity enhancement, which is obviously influenced by the change of oxidation states at the metal-oxide interface. Environmental transmission electron microscopy images unveil the atomic-scale redox behaviors at the nanoparticle interfaces with evolutions of the reducible oxide under the catalytic reaction. The important role of reactive interfaces between the transition metal atom and oxide-support explains the surface chemistry and heterogeneous catalysis over active sites on well-defined single crystal model surfaces, as well as nanoparticle catalysts. Overall, operando studies for metal-oxide interfaces can shed light on mechanistic insights into the tuning of catalytic activity at the molecular level and on improving catalytic performance by the SMSI effect.

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Section: Introduction To Operando Surface Chemistry On Model Catalyst...mentioning

confidence: 99%

Section: Introduction To Operando Surface Chemistry On Model Catalyst...mentioning

confidence: 99%

Operando Surface Studies on Metal-Oxide Interfaces of Bimetal and Mixed Catalysts

et al. 2021

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“…Because accurate manipulation of 2D supramolecular structures on the surface/interface is long-cherished by scientists with potential applications in nano-templates, molecular electronics, guest molecule accommodation, chiral ordering/induction and functional materials, external stimuli on 2D self-assemblies are widely studied, such as light irradiation, [1][2][3][4][5] solvent polarity, 6,7 concentration, [8][9][10][11] templates, 12 environmental temperature 13 and so on. It is known to us that the eventual self-assembled supramolecular structure on the surface/interface is the accurate equilibrium of molecule-molecule, molecule-substrate, molecule-solvent, and solvent-substrate interactions, which turns out to be a complex synergy process.…”

Section: Introductionmentioning

confidence: 99%

Temperature-induced self-assembly transformation: an effective external stimulus on 2D supramolecular structures

2022

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“…For such atomically flat surfaces, high-pressure scanning tunneling microscopy (HP-STM) has been the main technique of choice. 1 These studies have shown that at controlled ambient pressures and at room temperature (RT) and above even species with weak binding energy can have sufficient residence time on a surface that allows them to trigger reconstructions of the atomic structure; that is, under ambient conditions the surface structure dynamically adapts to its environment, and as a result completely new structures are often formed. In fact, even the most compact surfaces of some metals, which have the lowest energy configuration in a vacuum, were found to break up into clusters in the presence of gases at RT.…”

Section: Introductionmentioning

confidence: 99%

“…Restructuring of surfaces in the presence of gases in the mbar pressure range is an interesting equilibrium property of solid surfaces that is so far mostly studied on single crystals of transition metals and thin oxide films supported on metals. For such atomically flat surfaces, high-pressure scanning tunneling microscopy (HP-STM) has been the main technique of choice . These studies have shown that at controlled ambient pressures and at room temperature (RT) and above even species with weak binding energy can have sufficient residence time on a surface that allows them to trigger reconstructions of the atomic structure; that is, under ambient conditions the surface structure dynamically adapts to its environment, and as a result completely new structures are often formed.…”

Section: Introductionmentioning

confidence: 99%

Water Vapor and Alcohol Vapor Induced Healing of the Nanostructured KBr Surface

2022

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Using atomic force microscopy in the pressure range of 10 –10 mbar to several tens of mbar at room temperature, we demonstrate the restructuring of nanostructured KBr surfaces assisted by the presence of water, methanol, and ethanol vapors and the formation of solvation islands. On a flat KBr surface, the two-dimensional solvation islands start nucleating at the step edges and grow with time and with increasing relative pressure. Solvation islands of water wet the terraces; however, solvation islands of methanol and ethanol are localized around the step edges and do not wet the terraces. Two processes are observed on nanostructured KBr surfaces: the movement of the atomic steps and the formation of solvation islands. The first process takes place at comparatively lower pressures at around 1% relative pressure, whereas the second process starts at higher pressures at around 25% relative pressure and above. Furthermore, the second process takes place only after the complete relocation of the step edges and thereby formation of a nearly flat surface. This implies that there is a competition between the restructuring of the atomic steps and solvation layer formation, as both processes require solvated ions. Unlike in the case of a flat surface, solvation islands of alcohols wet the restructured surface due to a higher density of low-coordination sites.

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High-Pressure Scanning Tunneling Microscopy

Cited by 36 publications

References 227 publications

Operando Surface Studies on Metal-Oxide Interfaces of Bimetal and Mixed Catalysts

Operando Surface Studies on Metal-Oxide Interfaces of Bimetal and Mixed Catalysts

Temperature-induced self-assembly transformation: an effective external stimulus on 2D supramolecular structures

Water Vapor and Alcohol Vapor Induced Healing of the Nanostructured KBr Surface

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