Regulating coordination number in atomically dispersed Pt species on defect-rich graphene for n-butane dehydrogenation reaction

AbstractMetal nanoparticle (NP), cluster and isolated metal atom (or single atom, SA) exhibit different catalytic performance in heterogeneous catalysis originating from their distinct nanostructures. To maximize atom efficiency and boost activity for catalysis, the construction of structure–performance relationship provides an effective way at the atomic level. Here, we successfully fabricate fully exposed Pt3 clusters on the defective nanodiamond@graphene (ND@G) by the assistance of atomically dispersed Sn promoters, and correlated the n-butane direct dehydrogenation (DDH) activity with the average coordination number (CN) of Pt-Pt bond in Pt NP, Pt3 cluster and Pt SA for fundamentally understanding structure (especially the sub-nano structure) effects on n-butane DDH reaction at the atomic level. The as-prepared fully exposed Pt3 cluster catalyst shows higher conversion (35.4%) and remarkable alkene selectivity (99.0%) for n-butane direct DDH reaction at 450 °C, compared to typical Pt NP and Pt SA catalysts supported on ND@G. Density functional theory calculation (DFT) reveal that the fully exposed Pt3 clusters possess favorable dehydrogenation activation barrier of n-butane and reasonable desorption barrier of butene in the DDH reaction.

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Stability of heterogeneous single-atom catalysts: a scaling law mapping thermodynamics to kinetics

npj Computational Materials ◽

10.1038/s41524-020-00411-6 ◽

2020 ◽

Vol 6 (1) ◽

Author(s):

Ya-Qiong Su ◽

Long Zhang ◽

Yifan Wang ◽

Jin-Xun Liu ◽

Valery Muravev ◽

...

Keyword(s):

Metal Atom ◽

Density Functional ◽

Activation Barrier ◽

Scaling Law ◽

Precious Metals ◽

Catalytic Performance ◽

Single Atom ◽

Atom Diffusion ◽

Computational Screening ◽

Metal Support

Abstract Heterogeneous single-atom catalysts (SACs) hold the promise of combining high catalytic performance with maximum utilization of often precious metals. We extend the current thermodynamic view of SAC stability in terms of the binding energy (Ebind) of single-metal atoms on a support to a kinetic (transport) one by considering the activation barrier for metal atom diffusion. A rapid computational screening approach allows predicting diffusion barriers for metal–support pairs based on Ebind of a metal atom to the support and the cohesive energy of the bulk metal (Ec). Metal–support combinations relevant to contemporary catalysis are explored by density functional theory. Assisted by machine-learning methods, we find that the diffusion activation barrier correlates with (Ebind)2/Ec in the physical descriptor space. This diffusion scaling-law provides a simple model for screening thermodynamics to kinetics of metal adatom on a support.

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Support effects on adsorption and catalytic activation of O2 in single atom iron catalysts with graphene-based substrates

Physical Chemistry Chemical Physics ◽

10.1039/c7cp08301g ◽

2018 ◽

Vol 20 (10) ◽

pp. 7333-7341 ◽

Cited By ~ 25

Author(s):

Zheng-yang Gao ◽

Wei-jie Yang ◽

Xun-lei Ding ◽

Gang Lv ◽

Wei-ping Yan

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Density Functional Theory Calculation ◽

Single Atom ◽

Iron Catalysts ◽

Functional Theory ◽

Support Effects ◽

Catalytic Activation ◽

Theory Calculation

The adsorption and catalytic activation of O2 on single atom iron catalysts with graphene-based substrates were investigated systematically by density functional theory calculation.

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Research the sulfonation mechanism of urea in oleum by density functional theory calculation

Butlerov Communications ◽

10.37952/roi-jbc-01/19-59-8-32 ◽

2019 ◽

Vol 59 (8) ◽

pp. 32-39

Author(s):

Andrey A. Degtyarev ◽

◽

Alexandra V. Trishina ◽

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Activation Barrier ◽

Density Functional Theory Calculation ◽

Sulfamic Acid ◽

Isocyanic Acid ◽

Stable Complex ◽

Carbamic Acid ◽

Functional Theory ◽

Theory Calculation

The work investigates the sulfonation mechanism of urea in oleum, which is used in the synthesis of sulfamic acid. In addition to sulfamic acid, carbon dioxide is also released in the process. The method of density functional theory was used to model the sulfonation reaction using cation HSO3+ as a true sulfonating agent. All elementary acts, intermediates, and transition states of the reaction are determined. Six possible complexes of urea and cation HSO3+ are identified, of which two are reactive, formed through the bonding of the nitrogen atom of urea and sulfur of the HSO3+. The most stable complex is formed through the bonding of the oxygen atom of urea and sulfur of the HSO3+, from the reactive complexes it is separated by an activation barrier of 149.86 kJ/mol, so its formation inactivates the starting reagents and their return to a reactive state is possible only through interaction with negatively charged particles. The activation energies and thermal effects of the stages are calculated. The first stable intermediate of the process is isocyanic acid. Subsequently, isocyanic acid reacts with sulfuric by two mechanisms: the formation of urethane-like structures of NH2COOSO3H or carbamic acid. The second mechanism is preferred since it requires much milder conditions. Using the continuum models D-PCM and COSMO, the influence of the solvent on the reaction mechanism was studied. As a solvent, 100% sulfuric acid was taken. The maximum activation energy of elementary stages according to the first mechanism was: 167.37 (COSMO) kJ/mol, 169.77 (D-PCM), without solvent 180.38 kJ/mol. By the second mechanism: 57.38 (COSMO) kJ/mol, 59.91 (D-PCM), without solvent 91.15 kJ/mol. The number of elementary acts is 6 for the first mechanism and 7 for the second.

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