Controlling the Number of Atoms on Catalytic Metallic Clusters

Londoño-Calderón, Alejandra; Ponce, Arturo; Santiago, Ulises; Mejía-Rosales, Sergio; José–Yacamán, Miguel

doi:10.1016/b978-0-12-805090-3.00006-1

Cited by 5 publications

(7 citation statements)

References 107 publications

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“…Analogous multiwall signatures can be seen in many experimental studies. For example, HRTEM images of milled carbon soot materials are reported in Figure 1c of ref ( 90 ), presenting typical basic structural units of graphitic plane segments: a few nanometers in length and organized into multiwall features reminiscent of the ones observed in our phases. In another work, 91 soot and carbon black materials were studied via HRTEM, finding that the average interplanar distances of the graphene planes ranges around 3.4–3.5 Å, which is larger than the typical plane separation in graphite (3.35 Å), but within the values measured in our phases, i.e.…”

Section: Resultsmentioning

confidence: 79%

Diverse Phases of Carbonaceous Materials from Stochastic Simulations

et al. 2021

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Amorphous carbon systems are emerging to have unparalleled properties at multiple length scales, making them the preferred choice for creating advanced materials in many sectors, but the lack of long-range order makes it difficult to establish structure/property relationships. We propose an original computational approach to predict the morphology of carbonaceous materials for arbitrary densities that we apply here to graphitic phases at low densities from 1.15 to 0.16 g/cm3, including glassy carbon. This approach, dynamic reactive massaging of the potential energy surface (DynReaxMas), uses the ReaxFF reactive force field in a simulation protocol that combines potential energy surface (PES) transformations with global optimization within a multidescriptor representation. DynReaxMas enables the simulation of materials synthesis at temperatures close to experiment to correctly capture the interplay of activated vs entropic processes and the resulting phase morphology. We then show that DynReaxMas efficiently and semiautomatically produces atomistic configurations that span wide relevant regions of the PES at modest computational costs. Indeed, we find a variety of distinct phases at the same density, and we illustrate the evolution of competing phases as a function of density ranging from uniform vs bimodal distributions of pore sizes at higher and intermediate density (1.15 g/cm3 and 0.50 g/cm3) to agglomerated vs sparse morphologies, further partitioned into boxed vs hollow fibrillar morphologies, at lower density (0.16 g/cm3). Our observations of diverse phases at the same density agree with experiment. Some of our identified phases provide descriptors consistent with available experimental data on local density, pore sizes, and HRTEM images, showing that DynReaxMas provides a systematic classification of the complex field of amorphous carbonaceous materials that can provide 3D structures to interpret experimental observations.

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Section: Resultsmentioning

confidence: 79%

Diverse Phases of Carbonaceous Materials from Stochastic Simulations

et al. 2021

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“…An increasingly vast database of UTOx structures achieving atomistic details 32 has been being provided to researchers in the UTOx field by the combined use of surface science characterization techniques and theoretical methods 14,33 . Experimentally, progress has been strictly connected to instrumental development, with microscopy characterization pre-eminent in this field 3,34 , and still currently advancing at great speed 6,35,36 . Fairly recent is the development of in-situ characterization under environmental (e.g., catalytic) conditions, from the early achievements 37,38 to latest progresses 39,40 .…”

Section: Structural Motifsmentioning

confidence: 99%

“…Oxides are often insulator or semiconductors but charging effects are circumvented by their ultrathin character which enables charge transfer with the underlying metal. Starting with the early achievements 1,2 , great advances in both fabrication and characterization of hybrid metal/oxide interfacial systems have been realized and have rapidly grown in the last 2 decades or so, exploiting advances in microscopy and spectroscopy as applied to surface science, in conjunction with the pivotal role played by computational modelling [3][4][5][6] . Great efforts were devoted to the refinement of the synthesis and characterization techniques (both experimental and theoretical) thus achieving a high control of the obtained morphologies and in many cases clarification of their geometric structures down to atomic level [7][8][9][10][11][12][13] .…”

Section: Introductionmentioning

confidence: 99%

“…The different role played by these actors in the catalytic process (metal particles and oxide support) has been controversial for a long time. Only in latest years, thanks to the development of sophisticated experimental characterization techniques 6 aided by theoretical modeling, insights into the mechanistic steps of some (simple) catalytic processes have become clearer 12,[118][119][120][121][122] .…”

Section: Introductionmentioning

confidence: 99%

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2D oxides on metal materials: concepts, status, and perspectives

Barcaro

Fortunelli

2019

Phys. Chem. Chem. Phys.

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“…18 and 19. A general view of the characterization of metallic alloy nanoparticles in catalysis using aberration-corrected STEM at atomic resolution is presented in ref. 20, where a clear discussion is provided of the atomic distribution in the metallic nanoparticles affecting the catalytic activity of the nanoalloys, and the capability of high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM) methods to clarify these features. Down to subnanometer clusters, one of the first applications of AC-HR-STEM with direct atomicresolution imaging of calcined Au 24 Pd 1 clusters supported on multiwall carbon nanotubes using aberration-corrected STEM was given.…”

Section: Stemmentioning

confidence: 99%