Lanthanum-incorporated β-Ni(OH)2 nanoarrays for robust urea electro-oxidation

2021 ◽  
Vol 57 (16) ◽  
pp. 2029-2032
Author(s):  
Pin Hao ◽  
Ying Xin ◽  
Qian Wang ◽  
Liyi Li ◽  
Zhenhuan Zhao ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Catalytic Activity ◽  
Active Sites ◽  
Band Center ◽  
Electro Oxidation

A novel electrocatalyst exhibits superior catalytic activity contributed to its optimized electronic structure, downshift of its d-band center and well-exposed active sites.

Chemical etching manipulated local electronic structure upheaval of graphdiyne for efficient hydrogen evolution

2D Materials ◽  
2021 ◽  
Author(s):  
Kaikai Ma ◽  
Yunqi Zhao ◽  
Qingliang Liao ◽  
Zhaozhao Xiong ◽  
Xinting Li ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Catalytic Activity ◽  
Hydrogen Evolution ◽  
Chemical Etching ◽  
Active Sites ◽  
Theoretical Calculations ◽  
Great Expectation ◽  
Local Electronic Structure ◽  
A Current ◽  
Carbon Based

Abstract Graphdiyne (GDY), featured with unique sp2, sp-hybridized form and inherent inhomogeneous electron distribution, retains great expectation to be developed into highly efficient electrocatalysts for hydrogen evolution reaction (HER). However, the state-of-the-art GDY-based electrocatalysts still suffer from weak catalytic activity and sluggish reaction kinetics originating from the severe scarcity of in-plane active sites and insufficient electrical conductivity. Targeted at this bottleneck issue, electronic structure regulation, recognized as an extremely precise technical route, is promising to improve HER performances of carbon-based electrocatalysts. Herein, a facile controllable chemical etching strategy is well leveraged to introduce sp2-hybridized carbon-oxygen bonds (Csp2-O) into GDY for precise manipulation both of its electronic and spatial structures. Experimental results and theoretical calculations coherently manifest that Csp2-O introduction into GDY can not only induce its electronic structure upheaval to strengthen surface electron transport capability, but also trigger intensive carbon-oxygen p-p orbital hybridization to enhance the catalytic activity of acetylenic bond sites. As a result, the optimal GDY sample after etching delivers excellent HER performance with an overpotential of only 101 mV at a current density of 10 mA cm-2 and a low Tafel slope of 54 mV dec-1, which surpasses most of reported metal-free based electrocatalysts. This work provides a universal route for precise modulation of inherent electronic structure in GDY, and can be further extended to boost the overall performances of other carbon-based catalysts

scholarly journals Flexible and Responsive Nature of 2D Layered Conductive Metal-Organic Frameworks Determine Their Catalytic Activity in Oxidative Dehydrogenation of Propane

2020 ◽  
Author(s):  
Mohammad R. Momeni ◽  
Zeyu Zhang ◽  
Farnaz A. Shakib
Keyword(s):  
Electronic Structure ◽  
Catalytic Activity ◽  
Active Sites ◽  
Metal Organic Framework ◽  
Electronic Structure Calculations ◽  
Electronic Structure Methods ◽  
Catalytically Active ◽  
Metal Organic ◽  
Dynamics Simulations ◽  
Structure Calculations

A multi-faceted approach is introduced for investigating the effects of intrinsic and guest(water)-induced structural transformations/deformations and heterogeneity on catalytic activity of the 2D π-stacked layered Co3(HTTP)2, HTTP = hexathiotriphenylene, metal-organic framework. Through comprehensive molecular dynamics simulations coupled with periodic and cluster electronic structure calculations, we uncover a complex array of catalytically active sites in 2D Co3(HTTP)2 MOF which would have been entirely missed if conventional static electronic structure methods were to be employed.

Enhanced Catalytic Activity of PdNi Dilute Nanoalloy for Selective Phenylacetylene Hydrogenation

2021 ◽  
Vol 16 (3) ◽  
pp. 380-386
Author(s):  
Yue Zhang ◽  
Changjin XU ◽  
Yutong Wu ◽  
Song Li
Keyword(s):  
Electronic Structure ◽  
Catalytic Activity ◽  
Active Sites ◽  
Room Temperature ◽  
Catalytic Performance ◽  
Hydrogenation Catalysts ◽  
Dilute Alloys ◽  
Highly Active ◽  
Full Conversion ◽  
Dilute Alloy

Coordination of identical metals has significant impact on catalytic activity and selectivity of heterogeneous catalyst. Here, we show that the selectivity for hydrogenation of Pd can be manipulated by altering the coordinate environment. PdNi/SiO2 dilute alloy nanocatalysts have been synthesized at room temperature, which show effectively the unparalleled catalytic performance (about 100% selectivity to styrene) for phenylacetylene hydrogenation at 30 °C with full conversion. Structural and surface analyses show that the improvement in dispersion of the Pd active sites and the changed electronic structure of Pd contribute the catalytic performance significantly. This work is an important step towards developing highly active hydrogenation catalysts by forming dilute alloys.

scholarly journals Flexible and Responsive Nature of 2D Layered Conductive Metal-Organic Frameworks Determine Their Catalytic Activity in Oxidative Dehydrogenation of Propane

2020 ◽  
Author(s):  
Mohammad R. Momeni ◽  
Zeyu Zhang ◽  
Farnaz A. Shakib
Keyword(s):  
Electronic Structure ◽  
Catalytic Activity ◽  
Active Sites ◽  
Metal Organic Framework ◽  
Electronic Structure Calculations ◽  
Electronic Structure Methods ◽  
Catalytically Active ◽  
Metal Organic ◽  
Dynamics Simulations ◽  
Structure Calculations

A multi-faceted approach is introduced for investigating the effects of intrinsic and guest(water)-induced structural transformations/deformations and heterogeneity on catalytic activity of the 2D π-stacked layered Co3(HTTP)2, HTTP = hexathiotriphenylene, metal-organic framework. Through comprehensive molecular dynamics simulations coupled with periodic and cluster electronic structure calculations, we uncover a complex array of catalytically active sites in 2D Co3(HTTP)2 MOF which would have been entirely missed if conventional static electronic structure methods were to be employed.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Active Sites ◽  
Aerobic Oxidation ◽  
Catalytic Performance ◽  
Mcm 41

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.

A novel ligand with –NH2 and –COOH-decorated Co/Fe-based oxide for an efficient overall water splitting: dual modulation roles of active sites and local electronic structure

2020 ◽  
Vol 10 (18) ◽  
pp. 6266-6273
Author(s):  
Yalan Zhang ◽  
Zebin Yu ◽  
Ronghua Jiang ◽  
Jung Huang ◽  
Yanping Hou ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Water Splitting ◽  
Energy Demand ◽  
Active Sites ◽  
Electrode Materials ◽  
Global Energy ◽  
Overall Water Splitting ◽  
Local Electronic Structure ◽  
Electrochemical Water Splitting

Excellent electrochemical water splitting with remarkable durability can provide a solution to satisfy the increasing global energy demand in which the electrode materials play an important role.

Polymer structure and catalytic activity of ion exchangers

1981 ◽  
Vol 46 (7) ◽  
pp. 1577-1587 ◽  
Author(s):  
Karel Jeřábek
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Active Sites ◽  
Crosslinking Agent ◽  
Reaction Medium ◽  
Polymer Structure ◽  
Local Concentration ◽  
Ion Exchangers ◽  
Styrene Divinylbenzene ◽  
Kinetics Of

Catalytic activity of ion exchangers prepared by partial sulphonation of styrene-divinylbenzene copolymers in reesterifications of ethyl acetate by methanol and propanol, hydrolysis of ethyl acetate and in synthesis of bisphenol A has been compared with data on polymer structure of these catalysts and with distribution of the crosslinking agent, divinylbenzene, calculated from literature data on kinetics of copolymerisation of styrene with divinylbenzene. It was found that the polymer structure of ion exchangers influences catalytic activity predominantly by changing the local concentration of acid active sites. The results obtained indicated that the effect of transport phenomena on the rate of catalytic reactions does not depend on the degree of swelling of the ion exchangers in reaction medium but it is mainly dependent on the relative affinity of reaction components to the acid groups or to the polymer skeleton.

scholarly journals Oscillatory Behaviour of Ni Supported on ZrO2 in the Catalytic Partial Oxidation of Methane as Determined by Activation Procedure

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2495
Author(s):  
Daniela Pietrogiacomi ◽  
Maria Cristina Campa ◽  
Ida Pettiti ◽  
Simonetta Tuti ◽  
Giulia Luccisano ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Partial Oxidation ◽  
Active Sites ◽  
Direct Reduction ◽  
Partial Oxidation Of Methane ◽  
Catalytic Partial Oxidation ◽  
Oxidation Of Methane ◽  
Short Contact Time ◽  
Oxidation Reduction ◽  
Ni Species

Ni/ZrO2 catalysts, active and selective for the catalytic partial oxidation of methane to syngas (CH4-CPO), were prepared by the dry impregnation of zirconium oxyhydroxide (Zhy) or monoclinic ZrO2 (Zm), calcination at 1173 K and activation by different procedures: oxidation-reduction (ox-red) or direct reduction (red). The characterization included XRD, FESEM, in situ FTIR and Raman spectroscopies, TPR, and specific surface area measurements. Catalytic activity experiments were carried out in a flow apparatus with a mixture of CH4:O2 = 2:1 in a short contact time. Compared to Zm, Zhy favoured the formation of smaller NiO particles, implying a higher number of Ni sites strongly interacting with the support. In all the activated Ni/ZrO2 catalysts, the Ni–ZrO2 interaction was strong enough to limit Ni aggregation during the catalytic runs. The catalytic activity depended on the activation procedures; the ox-red treatment yielded very active and stable catalysts, whereas the red treatment yielded catalysts with oscillating activity, ascribed to the formation of Niδ+ carbide-like species. The results suggested that Ni dispersion was not the main factor affecting the activity, and that active sites for CH4-CPO could be Ni species at the boundary of the metal particles in a specific configuration and nuclearity.

scholarly journals Study of deactivation in mesocellular foam carbon (MCF-C) catalyst used in gas-phase dehydrogenation of ethanol

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yoottapong Klinthongchai ◽  
Seeroong Prichanont ◽  
Piyasan Praserthdam ◽  
Bunjerd Jongsomjit
Keyword(s):  
Catalytic Activity ◽  
Pore Size ◽  
Gas Phase ◽  
Surface Area ◽  
Active Sites ◽  
Operating Temperature ◽  
Coke Formation ◽  
Ethanol Conversion ◽  
Deactivation Of Catalyst ◽  
Dehydrogenation Of Ethanol

AbstractMesocellular foam carbon (MCF-C) is one the captivating materials for using in gas phase dehydrogenation of ethanol. Extraordinary, enlarge pore size, high surface area, high acidity, and spherical shape with interconnected pore for high diffusion. In contrary, the occurrence of the coke is a majority causes for inhibiting the active sites on catalyst surface. Thus, this study aims to investigate the occurrence of the coke to optimize the higher catalytic activity, and also to avoid the coke formation. The MCF-C was synthesized and investigated using various techniques. MCF-C was spent in gas-phase dehydrogenation of ethanol under mild conditions. The deactivation of catalyst was investigated toward different conditions. Effects of reaction condition including different reaction temperatures of 300, 350, and 400 °C on the deactivation behaviors were determined. The results indicated that the operating temperature at 400 °C significantly retained the lowest change of ethanol conversion, which favored in the higher temperature. After running reaction, the physical properties as pore size, surface area, and pore volume of spent catalysts were decreased owing to the coke formation, which possibly blocked the pore that directly affected to the difficult diffusion of reactant and caused to be lower in catalytic activity. Furthermore, a slight decrease in either acidity or basicity was observed owing to consumption of reactant at surface of catalyst or chemical change on surface caused by coke formation. Therefore, it can remarkably choose the suitable operating temperature to avoid deactivation of catalyst, and then optimize the ethanol conversion or yield of acetaldehyde.

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