scholarly journals Influence of confinement on free radical chemistry in layered nanostructures

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Khashayar Ghandi ◽  
Cody Landry ◽  
Tait Du ◽  
Maxime Lainé ◽  
Andres Saul ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Interlayer Space ◽  
Time Windows ◽  
Spectroscopic Method ◽  
Hyperfine Coupling Constant ◽  
Decay Rates ◽  
Particle Accelerator ◽  
Single Atom ◽  
Electron Recombination ◽  
Layered Clay

AbstractThe purpose of the present work was to study how chemical reactions and the electronic structure of atoms are affected by confinement at the sub-nanometer scale. To reach this goal, we studied the H atom in talc, a layered clay mineral. Talc is a highly 2D-confining material with the width of its interlayer space close to angstrom. We investigated talc with a particle accelerator-based spectroscopic method that uses elementary particles. This technique generates an exotic atom, muonium (Mu), which can be considered as an isotope of the H atom. Moreover, the technique allows us to probe a single atom (H atom) at any time and explore the effects of the layered clay on a single ion (proton) or atom. The cation/electron recombination happens in two time windows: one faster than a nanosecond and the other one at longer than microseconds. This result suggests that two types of electron transfer processes take place in these clay minerals. Calculations demonstrated that the interlayer space acts as a catalytic surface and is the primary location of cation/electron recombination in talc. Moreover, the studies of the temperature dependence of Mu decay rates, due to the formation of the surrogate of H2, is suggestive of an “H2” formation reaction that is thermally activated above 25 K, but governed by quantum diffusion below 25 K. The experimental and computational studies of the hyperfine coupling constant of Mu suggest that it is formed in the interlayer space of talc and that its electronic structure is extremely changed due to confinement. All these results imply that the chemistry could be strongly affected by confinement in the interlayer space of clays.

Oxygen defects-stabilized heterogeneous single atom catalysts: preparation, property and catalytic application

2021 ◽  
Author(s):  
Lei Zhang ◽  
Xiu-Fei Zhao ◽  
Zhengqiu Yuan ◽  
Ming Wu ◽  
Hu Zhou
Keyword(s):  
Electronic Structure ◽  
Single Atom ◽  
Metal Species ◽  
Coordination Environment ◽  
Chemical Catalysis ◽  
Catalytic Application ◽  
Oxygen Defects ◽  
Catalysts Preparation

Single atom catalysts (SACs) show outstanding activity and selectivity in chemical catalysis owing to its unique electronic structure and unsaturated coordination environment, in which every dispersed metal species on support...

scholarly journals Modulating electronic structure of metal-organic frameworks by introducing atomically dispersed Ru for efficient hydrogen evolution

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yamei Sun ◽  
Ziqian Xue ◽  
Qinglin Liu ◽  
Yaling Jia ◽  
Yinle Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Catalyst Design ◽  
Single Atom ◽  
Hydrogen Energy ◽  
Structure Of Metal ◽  
Metal Organic

AbstractDeveloping high-performance electrocatalysts toward hydrogen evolution reaction is important for clean and sustainable hydrogen energy, yet still challenging. Herein, we report a single-atom strategy to construct excellent metal-organic frameworks (MOFs) hydrogen evolution reaction electrocatalyst (NiRu0.13-BDC) by introducing atomically dispersed Ru. Significantly, the obtained NiRu0.13-BDC exhibits outstanding hydrogen evolution activity in all pH, especially with a low overpotential of 36 mV at a current density of 10 mA cm−2 in 1 M phosphate buffered saline solution, which is comparable to commercial Pt/C. X-ray absorption fine structures and the density functional theory calculations reveal that introducing Ru single-atom can modulate electronic structure of metal center in the MOF, leading to the optimization of binding strength for H2O and H*, and the enhancement of HER performance. This work establishes single-atom strategy as an efficient approach to modulate electronic structure of MOFs for catalyst design.

Methane Activation on Single-Atom Ir-doped Metal Nanoparticles from First-principles

2021 ◽  
Author(s):  
Yugang Ren ◽  
Xiaojing Liu ◽  
Zhaojun Zhang ◽  
Xiangjian Shen
Keyword(s):  
Electronic Structure ◽  
Heterogeneous Catalysis ◽  
Metal Nanoparticles ◽  
First Principles ◽  
Methane Activation ◽  
Single Atom ◽  
Surface Electronic Structure

The breaking of the C-H bond of CH4 is of great importance and one of the most efficient strategies in heterogeneous catalysis is to alter surface electronic structure by doping...

scholarly journals Single-atom catalysts for CO2 electroreduction with significant activity and selectivity improvements

2017 ◽  
Vol 8 (2) ◽  
pp. 1090-1096 ◽  
Author(s):  
Seoin Back ◽  
Juhyung Lim ◽  
Na-Young Kim ◽  
Yong-Hyun Kim ◽  
Yousung Jung
Keyword(s):  
Electronic Structure ◽  
High Activity ◽  
Single Atom ◽  
Atomic Ensemble ◽  
Significant Activity ◽  
Co2 Electroreduction

We propose the great potential of single atom catalysts (SACs) for CO2 electroreduction with high activity and selectivity predictions over a competitive H2 evolution reaction. We find the lack of an atomic ensemble for adsorbate binding and unique electronic structure of the single atom catalysts play an important role.

scholarly journals Unified Mechanistic Understanding of CO2 Reduction to CO on Transition Metal and Single Atom Catalysts

2021 ◽  
Author(s):  
Sudarshan Vijay ◽  
Wen Ju ◽  
Sven Brückner ◽  
Peter Strasser ◽  
Karen Chan
Keyword(s):  
Electron Transfer ◽  
Electronic Structure ◽  
Transition Metal ◽  
Density Functional ◽  
Co2 Reduction ◽  
Electron Transfer Reaction ◽  
Dipole Field ◽  
Single Atom ◽  
Activity Measurements ◽  
Carbon Catalysts

<p>CO is the simplest product from CO<sub>2</sub> electroreduction (CO<sub>2</sub>R), but the identity and nature of its rate limiting step remains controversial. Here we investigate the activity of both transition metals (TMs) and metal-nitrogen doped carbon catalysts (MNCs), and a present unified mechanistic picture of CO<sub>2</sub>R to for both these classes of catalysts. By consideration of the electronic structure through a Newns-Andersen model, we find that on MNCs, like TMs, electron transfer to CO<sub>2</sub><sub> </sub>is facile, such that CO<sub>2</sub> (g) adsorption is driven by adsorbate dipole-field interactions. Using density functional theory with explicit consideration of the interfacial field, we find CO<sub>2</sub> * adsorption to generally be limiting on TMs, while MNCs can be limited by either CO<sub>2</sub>* adsorption or by the proton-electron transfer reaction to form COOH*. We evaluate these computed mechanisms against pH-dependent experimental activity measurements on CO<sub>2</sub>R to CO activity for Au, FeNC, and NiNC. We present a unified activity volcano that, in contrast to previous analyses, includes the decisive CO<sub>2</sub>*<sub> </sub>and COOH* binding strengths as well as the critical adsorbate dipole-field interactions. We furthermore show that MNC catalysts are tunable towards higher activity away from transition metal scaling, due to the stabilization of larger dipoles resulting from their discrete and narrow <i>d</i>-states. The analysis suggests two design principles for ideal catalysts: moderate CO<sub>2</sub>* and COOH* binding strengths as well as large dipoles on the CO<sub>2</sub>*<sub> </sub>intermediate. We suggest that these principles can be exploited in materials with similar electronic structure to MNCs, such as supported single-atom catalysts, molecules, and nanoclusters, 2D materials, and ionic compounds towards higher CO<sub>2</sub>R activity. This work captures the decisive impact of adsorbate dipole-field interactions in CO<sub>2</sub>R to CO and paves the way for computational-guided design of new catalysts for this reaction.</p>

HREM study of Fe—pillared smectite

1990 ◽  
Vol 48 (4) ◽  
pp. 282-283
Author(s):  
P.L. Hansen ◽  
C. Bender Koch ◽  
S. Mørup
Keyword(s):  
Metal Oxide ◽  
Molecular Sieves ◽  
Direct Evidence ◽  
Interlayer Space ◽  
Active Surface ◽  
Interlayer Spacing ◽  
Active Surface Area ◽  
Oxide Precursor ◽  
Layered Clay ◽  
Structural Methods

During the process of pillaring smectite, a metal oxide precursor is introduced into the interlayer space of the layered clay mineral. By subsequent heating of the precursor, a metal oxide forms, increasing the interlayer spacing 0.5—1.0 nm, as observed in XRD.Pillaring of clays increases the active surface area, and the materials may find use as molecular sieves and catalysts.Most of the information on the oxide pillars has been derived from indirect spectroscopic and structural methods. In the present study we have used HREM to obtain direct evidence for the pillar formation.

Electronic structure regulation of cobalt oxide clusters for promoting photocatalytic hydrogen evolution

2022 ◽  
Author(s):  
Guowei Yang ◽  
Bo Yan ◽  
Yan He
Keyword(s):  
Electronic Structure ◽  
Cobalt Oxide ◽  
Hydrogen Evolution ◽  
Solar Light ◽  
Single Atom ◽  
Hydrogen Energy ◽  
Atomic Cluster ◽  
Water Decomposition ◽  
Photocatalytic Hydrogen Evolution ◽  
Structure Regulation

Photocatalysis for water decomposition under solar light is a promising route to produce clean hydrogen energy. Although both single atom catalysts (SACs) and atomic cluster catalysts are effective ways to...

Modulating Electronic Structure of Metal-Organic Frameworks by Introducing Atomically Dispersed Ru for Efficient Hydrogen Evolution

2020 ◽  
Author(s):  
Yamei Sun ◽  
Ziqian Xue ◽  
Qinglin Liu ◽  
Yaling Jia ◽  
Yinle Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Density Functional ◽  
Metal Organic Frameworks ◽  
Catalyst Design ◽  
Single Atom ◽  
Hydrogen Energy ◽  
Structure Of Metal ◽  
Metal Organic

Abstract Developing high-performance electrocatalysts toward hydrogen evolution reaction is important for clean and sustainable hydrogen energy, yet still challenging. Herein, we report a single-atom strategy to construct excellent metal-organic frameworks (MOFs) hydrogen evolution reaction (HER) electrocatalyst (NiRu0.13-BDC, BDC: terephthalic acid) by introducing atomically dispersed Ru. Significantly, the obtained NiRu0.13-BDC exhibits outstanding HER activity in all pH, especially with a low overpotential of only 36 mV at a current density of 10 mA cm-2 in 1 M phosphate buffered saline (PBS) solution, which is comparable to commercial Pt/C. X-ray absorption fine structures and the density functional theory calculations reveal that introducing Ru single-atom can modulate electronic structure of metal center in the MOF, leading to the optimization of binding strength for H2O and H*, and the enhancement of HER performance. This work establishes single-atom strategy as an efficient approach to modulate electronic structure of MOFs for catalyst design.

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