Effect of the coordination environment of Cu in Cu2O on the electroreduction of CO2 to ethylene

2020 ◽  
Vol 22 (19) ◽  
pp. 6340-6344
Author(s):  
Yahui Wu ◽  
Chunjun Chen ◽  
Xupeng Yan ◽  
Shoujie Liu ◽  
Mengen Chu ◽  
...  
Keyword(s):  
Coordination Number ◽  
Crucial Role ◽  
Crystal Surface ◽  
Catalytic Performance ◽  
Electrocatalytic Reduction ◽  
Coordination Environment

The coordination number (CN) of Cu–Cu and Cu–O in Cu2O play crucial role on the catalytic performance of CO2 electrocatalytic reduction to C2H4. And the CN of Cu–Cu and Cu–O could be tuned by changing the crystal surface and size of Cu2O.

scholarly journals Robust and efficient hydrogenation of carbonyl compounds catalysed by mixed donor Mn(I) pincer complexes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenjun Yang ◽  
Ivan Yu. Chernyshov ◽  
Robin K. A. van Schendel ◽  
Manuela Weber ◽  
Christian Müller ◽  
...  
Keyword(s):  
Noble Metal ◽  
Crucial Role ◽  
Carbonyl Compounds ◽  
Catalytic Performance ◽  
Hydrogen Atmosphere ◽  
Pincer Complexes ◽  
Catalyst Activation ◽  
Hydrogenation Catalysts ◽  
Induction Times

AbstractAny catalyst should be efficient and stable to be implemented in practice. This requirement is particularly valid for manganese hydrogenation catalysts. While representing a more sustainable alternative to conventional noble metal-based systems, manganese hydrogenation catalysts are prone to degrade under catalytic conditions once operation temperatures are high. Herein, we report a highly efficient Mn(I)-CNP pre-catalyst which gives rise to the excellent productivity (TOF° up to 41 000 h−1) and stability (TON up to 200 000) in hydrogenation catalysis. This system enables near-quantitative hydrogenation of ketones, imines, aldehydes and formate esters at the catalyst loadings as low as 5–200 p.p.m. Our analysis points to the crucial role of the catalyst activation step for the catalytic performance and stability of the system. While conventional activation employing alkoxide bases can ultimately provide catalytically competent species under hydrogen atmosphere, activation of Mn(I) pre-catalyst with hydride donor promoters, e.g. KHBEt3, dramatically improves catalytic performance of the system and eliminates induction times associated with slow catalyst activation.

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

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaowen Chen ◽  
Mi Peng ◽  
Xiangbin Cai ◽  
Yunlei Chen ◽  
Zhimin Jia ◽  
...  
Keyword(s):  
Coordination Number ◽  
Density Functional ◽  
Activation Barrier ◽  
Density Functional Theory Calculation ◽  
Catalytic Performance ◽  
Atomic Level ◽  
Metal Nanoparticle ◽  
Single Atom ◽  
Nano Structure ◽  
Theory Calculation

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.

Regulating the electronic properties of MoSe2 to improve its CO2 electrocatalytic reduction performance via atomic doping

2021 ◽  
Vol 45 (12) ◽  
pp. 5350-5356
Author(s):  
Jingjing Ye ◽  
Dewei Rao ◽  
Xiaohong Yan
Keyword(s):  
Electronic Properties ◽  
Electronic Property ◽  
Catalytic Performance ◽  
Reaction Intermediates ◽  
Electrocatalytic Reduction

The atomic environment should heavily influence the performance of CO2 reduction, and the regulated electronic property of reaction intermediates and metals (Cu) is responsible for the high catalytic performance of CH4 production.

Matrix-Mineral Relationships-A. Morphologist's Viewpoint

1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 922-929 ◽  
Author(s):  
M.U. Nylen
Keyword(s):  
Organic Material ◽  
Crucial Role ◽  
Crystal Surface ◽  
Organic Matrix ◽  
The Other ◽  
Enamel Matrix ◽  
Initial Cell ◽  
Cell Product ◽  
Ultrastructural Morphology ◽  
The Matrix

The literature on the ultrastructural morphology of the enamel matrix and its relationship to the crystals is reviewed. Two morphological entities of the matrix are discussed: One is the so-called stippled material which may be the initial cell product; the other, variously described as fibrillar, lamellar, tubular or helical, is thought by many to play a crucial role in nucleation and orientation of the crystals. A number of observations, however, suggest that the latter structures form secondarily to the crystals and that in reality they represent organic material adsorbed to the crystal surface and maintained as independent structures upon removal of the mineral. The need for additional studies is stressed including systematic studies of interactions between constituents of the organic matrix and the apatite crystals.

Structure and stereochemistry in 'f-block' complexes of high coordination number. VII. The [M(unidentate X)2(unidentate Y)6] system: Crystal structure of hexaaquadichloroeuropium(III) chloride (a redetermination)

1983 ◽  
Vol 36 (3) ◽  
pp. 477 ◽  
Author(s):  
DL Kepert ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Coordination Number ◽  
Title Compound ◽  
Chlorine Atoms ◽  
Coordination Environment ◽  
Twofold Axis ◽  
High Coordination Number ◽  
Europium Atom ◽  
High Coordination

The crystal structure of the title compound [EuCl2(OH2)2]Cl ('europium trichloride hexahydrate') has been redetermined from single-crystal diffractometer data at 295 K and refined to a residual of 0.040 for 1094 independent 'observed' reflections. Crystals are monoclinic, P2/n, a 9.659(3), b 6.529(2), c 7.936(4) �, β 93.67(4)�, Z 2. The europium atom lies on a crystallographic twofold axis, which passes between the two planes of a square-antiprismatic coordination environment in which the two chlorine atoms, on opposite faces, lie cis to each other. Eu-O distances range from 2.401(6) to 2.431(5) �; Eu-Cl is 2.774(2) �.

scholarly journals Effect of the oxygen coordination environment of Ca–Mn oxides on the catalytic performance of Pd supported catalysts for aerobic oxidation of 5-hydroxymethyl-2-furfural

2019 ◽  
Vol 9 (23) ◽  
pp. 6659-6668 ◽  
Author(s):  
Jie Yang ◽  
Haochen Yu ◽  
Yanbing Wang ◽  
Fuyuan Qi ◽  
Haodong Liu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Charge Transfer ◽  
Active Sites ◽  
Supported Catalysts ◽  
Aerobic Oxidation ◽  
Oxygen Adsorption ◽  
Catalytic Performance ◽  
Coordination Environment ◽  
Oxygen Coordination ◽  
Mn Oxides

Pd/CaMn2O4 provides ideal active sites for oxygen adsorption and desorption, resulting in the promoted charge transfer ability and catalytic activity.

scholarly journals Modulating the local coordination environment of single-atom catalysts for enhanced catalytic performance

Nano Research ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1842-1855 ◽  
Author(s):  
Xinyuan Li ◽  
Hongpan Rong ◽  
Jiatao Zhang ◽  
Dingsheng Wang ◽  
Yadong Li
Keyword(s):  
Catalytic Performance ◽  
Single Atom ◽  
Coordination Environment ◽  
Local Coordination

scholarly journals Crystal Structure and Optical Properties of a Homometallic Heterotrinuclear Europium(III) Complex – a Cationic Eu(III) ion Coordinated by two [Eu(III)DOTA]- Complexes

2021 ◽  
Author(s):  
Maria Storm Thomsen ◽  
Ander Østergård Madsen ◽  
Thomas Just Sørensen
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Coordination Number ◽  
Luminescence Spectroscopy ◽  
Data Sets ◽  
Complex Data ◽  
Triclinic Space Group ◽  
Coordination Environment ◽  
High Asymmetry ◽  
State Luminescence

The structure and solid state luminescence properties of a homometallic heterotrinuclear [Eu(μO)5(OH2)3][Eu(DOTA)(H2O)]2Cl crystal was determined and was found to have two sites: a free europium(III) ion and a [Eu(DOTA)(H2O)]- complex. The trinuclear compound crystallizes in a laminar structure in triclinic space group P. The crystal structure was determined using complex data treatment due to non-merohedric twinning. Experimental data sets were recorded with large redundancy and separated according to scattering domain in order to obtain a reliable structure, which revealed the configuration of the europium(III) sites. In first site, the europium(III) 1,4,7,10-tetrazacyclododecane-1,4,7,10-tetraacetate (Eu.DOTA) complex was found to adopt a capped twisted square antiprismatic (cTSAP) conformation, where a capping water molecule increased the coordination number of the europium(III) site to nine (CN = 9). In the second site, the cationic europium(III) ion was found to be coordinated by three water molecules and five oxy groups from neighboring [Eu(DOTA)(H2O)]- complexes. The coordination geometry of this site was found to be a compressed square antiprism (SAP), and the coordination number of the europium(III) ion was found to be eight (CN = 8). A large increase in rate constant of luminescence was observed for Eu(III) in [Eu(DOTA)(H2O)]- in solid state luminescence spectroscopy measurements compared to in solution, which lead to investigations of single-crystals in deuterated media to exclude additional effects of quenching. We conclude that the most probable cause of the decrease in observed luminescence lifetimes is the high asymmetry of the coordination environment of [Eu(DOTA)(D2O)]- in the [Eu(μO)5(OD2)3][Eu(DOTA)(D2O)]2Cl crystals<br>

scholarly journals Effect of Ion-Exchange Sequences on Catalytic Performance of Cerium-Modified Cu-SSZ-13 Catalysts for NH3-SCR

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 997
Author(s):  
Yan Wang ◽  
Zhaoqiang Li ◽  
Zhiyong Ding ◽  
Na Kang ◽  
Rongrong Fan ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Copper Ions ◽  
Reduction Process ◽  
Catalytic Performance ◽  
Adsorbed Species ◽  
Exchange Method ◽  
Coordination Environment ◽  
Nh3 Scr ◽  
Nox Conversion ◽  
Acidic Sites

Cerium-modified Cu-SSZ-13 catalysts were prepared by an aqueous ion-exchange method, and Ce and Cu were incorporated through different ion-exchange sequences. The results of NH3-SCR activity evaluations displayed that Cu1(CeCu)2 catalyst presented excellent catalytic activity, and over 90% NOx conversion was obtained across the temperature range of 200–500 °C. The characterization results showed that the ion-exchange sequence of Cu and Ce species influenced the crystallinity of the zeolites and the coordination of Al. A small amount of Ce could participate in the reduction process and change the location and coordination environment of copper ions. Furthermore, Ce-modified Cu-SSZ-13 catalysts possessed more acidic sites due to their containing replacement of Ce and movement of Cu in the preparation process. The cooperation of strong redox abilities and NH3 storage capacity led to the increase of active adsorbed species adsorption and resulted in better activity of Cu1(CeCu)2.

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