Chapter 6. Bridging Homogeneous and Heterogeneous Systems: Atomically Dispersed Metal Atoms in Carbon Matrices for Electrocatalytic CO2 Reduction

2020 ◽  
pp. 226-286
Author(s):  
Hui-Yun Jeong ◽  
Mani Balamurugan ◽  
Chang Hyuck Choi ◽  
Ki Tae Nam
Keyword(s):  
Heterogeneous Systems ◽  
Co2 Reduction ◽  
Metal Atoms

Single metal atoms regulated flexibly by a 2D InSe substrate for CO2 reduction electrocatalysts

2019 ◽  
Vol 7 (14) ◽  
pp. 8210-8217 ◽  
Author(s):  
Chen-Xu Zhao ◽  
Guo-Xu Zhang ◽  
Wang Gao ◽  
Qing Jiang
Keyword(s):  
Co2 Reduction ◽  
Metal Atoms

The CO2 electroreduction reaction (CRR) is impeded by the low selectivity and high limiting potential of catalysts.

CO2 Reduction on Single-Atom Ir Catalysts with Chemical Functionalization

2022 ◽  
Author(s):  
Zheng-Zhe Lin ◽  
Xi-Mei Li ◽  
Xin-Wei Chen ◽  
Xi Chen
Keyword(s):  
Co2 Reduction ◽  
Catalytic Performance ◽  
Single Atom ◽  
Electrochemical Reactions ◽  
Catalytic Systems ◽  
Chemical Functionalization ◽  
Metal Atoms

As promising catalytic systems, single-atom catalysts (SACs) demonstrate improved catalytic performance for electrochemical reactions. However, the pinning of metal atoms on surfaces usually depends on the adsorption on defects. In...

scholarly journals Comparing Molecular Mechanisms in Solar NH3 Production and Relations with CO2 Reduction

2020 ◽  
Author(s):  
Domenico Mallamace ◽  
Georgia Papanikolaou ◽  
Siglinda Perathoner ◽  
Gabriele Centi ◽  
Paola Lanzafame
Keyword(s):  
N2 Fixation ◽  
Fossil Fuels ◽  
Molecular Mechanisms ◽  
Co2 Reduction ◽  
Enzymatic Conversion ◽  
Plasma Catalysis ◽  
Oxide Hydroxide ◽  
Metal Atoms ◽  
Simultaneous Transfer ◽  
Defective Sites

Molecular mechanisms for N2 fixation (solar NH3) and CO2 conversion to C2+ products in enzymatic conversion (Nitrogenase), electrocatalysis, metal-complexes and plasma-catalysis are analysed and compared. It is evidenced that differently from what present in thermal and plasma-catalysis, the electrocatalysis path requires not only the direct coordination and hydrogenation of undissociated N2 molecule, but to realize a series of features present in the Nitrogenase mechanism. There is the need of i) a multi-electron and -proton simultaneous transfer, not as sequential steps, ii) forming bridging metal hydride species, iii) generate intermediates stabilized by bridging multiple metal atoms, iv) have the capability of the same sites to be effective both in N2 fixation and in COx reduction to C2+ products. Only iron oxide/hydroxide stabilized at defective sites of nanocarbons was found to have these features. This comparison of the molecular mechanisms in solar NH3 production and relations with CO2 reduction is proposed to be a source of inspiration to develop the next generation electrocatalysts to address the challenging transition to a future sustainable energy and chemistry beyond fossil fuels.

scholarly journals Comparing Molecular Mechanisms in Solar NH3 Production and Relations with CO2 Reduction

2020 ◽  
Vol 22 (1) ◽  
pp. 139
Author(s):  
Domenico Mallamace ◽  
Georgia Papanikolaou ◽  
Siglinda Perathoner ◽  
Gabriele Centi ◽  
Paola Lanzafame
Keyword(s):  
N2 Fixation ◽  
Fossil Fuels ◽  
Molecular Mechanisms ◽  
Co2 Reduction ◽  
Enzymatic Conversion ◽  
Plasma Catalysis ◽  
Oxide Hydroxide ◽  
Metal Atoms ◽  
Simultaneous Transfer ◽  
Defective Sites

Molecular mechanisms for N2 fixation (solar NH3) and CO2 conversion to C2+ products in enzymatic conversion (nitrogenase), electrocatalysis, metal complexes and plasma catalysis are analyzed and compared. It is evidenced that differently from what is present in thermal and plasma catalysis, the electrocatalytic path requires not only the direct coordination and hydrogenation of undissociated N2 molecules, but it is necessary to realize features present in the nitrogenase mechanism. There is the need for (i) a multi-electron and -proton simultaneous transfer, not as sequential steps, (ii) forming bridging metal hydride species, (iii) generating intermediates stabilized by bridging multiple metal atoms and (iv) the capability of the same sites to be effective both in N2 fixation and in COx reduction to C2+ products. Only iron oxide/hydroxide stabilized at defective sites of nanocarbons was found to have these features. This comparison of the molecular mechanisms in solar NH3 production and CO2 reduction is proposed to be a source of inspiration to develop the next generation electrocatalysts to address the challenging transition to future sustainable energy and chemistry beyond fossil fuels.

Environment of Metal–O–Fe Bonds Enabling High Activity in CO2 Reduction on Single Metal Atoms and on Supported Nanoparticles

2021 ◽  
Vol 143 (14) ◽  
pp. 5540-5549
Author(s):  
Yifeng Zhu ◽  
Simuck F. Yuk ◽  
Jian Zheng ◽  
Manh-Thuong Nguyen ◽  
Mal-Soon Lee ◽  
...  
Keyword(s):  
High Activity ◽  
Co2 Reduction ◽  
Supported Nanoparticles ◽  
Metal Atoms

scholarly journals Recent Advances in Transition-Metal-Mediated Electrocatalytic CO2 Reduction: From Homogeneous to Heterogeneous Systems

Catalysts ◽  
2017 ◽  
Vol 7 (12) ◽  
pp. 373 ◽  
Author(s):  
Da-Ming Feng ◽  
Yun-Pei Zhu ◽  
Ping Chen ◽  
Tian-Yi Ma
Keyword(s):  
Transition Metal ◽  
Heterogeneous Systems ◽  
Co2 Reduction ◽  
Recent Advances

Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system

1992 ◽  
Vol 50 (1) ◽  
pp. 58-59
Author(s):  
S. Ritchie ◽  
J. C. Bennett ◽  
A. Prodan ◽  
F.W. Boswell ◽  
J.M. Corbett
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Direct Evidence ◽  
Density Wave ◽  
Wave System ◽  
Modulated Phases ◽  
Metal Atoms ◽  
Incommensurate Modulation ◽  
End Members ◽  
Modulation Wave Vector

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.

Ultra high resolution SEM at high voltage images individual fab fragments applied as molecular label to cell surface receptors

1989 ◽  
Vol 47 ◽  
pp. 70-71
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Resolution ◽  
High Energy ◽  
Metal Coating ◽  
Beam Diameter ◽  
Surface Receptors ◽  
Surface Mobility ◽  
Metal Atoms ◽  
Shadowing Effect ◽  
Imaging Mode ◽  
Deposition Techniques

Topographic ultra high resolution can now routinely be established on bulk samples in cold field emission scanning electron microscopy with a second generation of microscopes (FSEM) designed to provide 0.5 nm probe diameters. If such small probes are used for high magnification imaging, topographic contrast is so high that remarkably fine details can be imaged on 2DMSO/osmium-impregnated specimens at ribosome surfaces even without a metal coating. On TCH/osmium-impregnated specimens topographic resolution can be increased further if the SE-I imaging mode is applied. This requires that beam diameter and metal coating thickness be made smaller than the SE range of ~1 nm and background signal contributions be reduced. Subnanometer small probes can be obtained (only) at high accelerating voltages. Subnanometer thin continuous metal films can be produced under the following conditions: self-shadowing effect between metal atoms must be reduced through appropriate deposition techniques and surface mobility of metal atoms must be diminished through high energy sputtering and/or specimen cooling.

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