Unravelling the nature, evolution and spatial gradients of active species and active sites in the catalyst bed of unpromoted and K/Ba-promoted Cu/Al2O3 during CO2 capture-reduction

2016 ◽  
Vol 4 (18) ◽  
pp. 6878-6885 ◽  
Author(s):  
Tsuyoshi Hyakutake ◽  
Wouter van Beek ◽  
Atsushi Urakawa
Keyword(s):  
Co2 Capture ◽  
Active Sites ◽  
Chemical Species ◽  
Reduction Process ◽  
Active Species ◽  
Surface Chemical ◽  
Time Resolved ◽  
Spatial Gradients ◽  
Space And Time

Space- and time-resolved operando DRIFTS, XAFS, and XRD uncovered the involved surface chemical species and active sites, especially the unique functions of K and Cu, during the CO2 capture-reduction process.

scholarly journals Morphological and Elemental Investigations on Co–Fe–B–O Thin Films Deposited by Pulsed Laser Deposition for Alkaline Water Oxidation: Charge Exchange Efficiency as the Prevailing Factor in Comparison with the Adsorption Process

2021 ◽  
Author(s):  
Y. Popat ◽  
M. Orlandi ◽  
S. Gupta ◽  
N. Bazzanella ◽  
S. Pillai ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Water Oxidation ◽  
Active Sites ◽  
High Surface ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Active Species ◽  
Laser Deposition ◽  
Core Shell ◽  
Adsorption Sites

Abstract Mixed transition-metals oxide electrocatalysts have shown huge potential for electrochemical water oxidation due to their earth abundance, low cost and excellent electrocatalytic activity. Here we present Co–Fe–B–O coatings as oxygen evolution catalyst synthesized by Pulsed Laser Deposition (PLD) which provided flexibility to investigate the effect of morphology and structural transformation on the catalytic activity. As an unusual behaviour, nanomorphology of 3D-urchin-like particles assembled with crystallized CoFe2O4 nanowires, acquiring high surface area, displayed inferior performance as compared to core–shell particles with partially crystalline shell containing boron. The best electrochemical activity towards water oxidation in alkaline medium with an overpotential of 315 mV at 10 mA/cm2 along with a Tafel slope of 31.5 mV/dec was recorded with core–shell particle morphology. Systematic comparison with control samples highlighted the role of all the elements, with Co being the active element, boron prevents the complete oxidation of Co to form Co3+ active species (CoOOH), while Fe assists in reducing Co3+ to Co2+ so that these species are regenerated in the successive cycles. Thorough observation of results also indicates that the activity of the active sites play a dominating role in determining the performance of the electrocatalyst over the number of adsorption sites. The synthesized Co–Fe–B–O coatings displayed good stability and recyclability thereby showcasing potential for industrial applications. Graphic Abstract

Selective hydrogenation of nitroarenes under mild conditions by the optimization of active sites in a well defined Co@NC catalyst

2020 ◽  
Vol 22 (17) ◽  
pp. 5730-5741
Author(s):  
Shuo Chen ◽  
Li-Li Ling ◽  
Shun-Feng Jiang ◽  
Hong Jiang
Keyword(s):  
Particle Size ◽  
Catalytic Hydrogenation ◽  
Selective Hydrogenation ◽  
Active Sites ◽  
Metal Organic Framework ◽  
Nitro Compounds ◽  
Active Species ◽  
Mild Conditions ◽  
Metal Organic ◽  
Aromatic Nitro

The defined catalyst (Co@NC) is prepared through the pyrolysis of the Co-centered metal–organic framework (MOF), in which Co active species (Co–Nx, surface Co NPs) and particle size play important roles in the catalytic hydrogenation of aromatic nitro compounds.

scholarly journals Preparation of magnetic nanoparticles via chemically induced transition

2017 ◽  
Vol 7 ◽  
pp. 184798041668716 ◽  
Author(s):  
Yanshuang Chen ◽  
Qin Chen ◽  
Hong Mao ◽  
Ting Zhang ◽  
Xiaoyan Qiu ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Chemical Species ◽  
Chemical Components ◽  
Surface Chemical ◽  
Mass Percentage ◽  
Magnesium Oxide Nanoparticles ◽  
Chemically Induced ◽  
Bulk Chemical ◽  
Moderate Range ◽  
Magnetization Behavior

Using an FeOOH/Mg(OH)2 precursor, maghemite-based magnetic nanoparticles can be prepared by a chemically induced transition in an Iron(II) chloride (FeCl2) treating solution. FeCl2 solutions of various concentrations were used to investigate the dependence of sample components and magnetization on the treating solution. The bulk chemical species, crystal structures, surface chemical components, morphologies, and specific magnetizations of the samples were characterized. When the concentration of FeCl2 solution was in a moderate range of 0.060–0.250 M, maghemite nanoparticles coated by hydromolysite, that is, maghemite/hydromolysite nanoparticles, could be prepared. At lower concentrations, below 0.030 M, the samples contained maghemite/hydromolysite and magnesium oxide nanoparticles, and at higher concentrations, up to 1.000 M, the samples contained maghemite/hydromolysite and hydromolysite nanoparticles. The molar and mass percentages of each phase were estimated for each sample. The apparent magnetization behavior of the samples, which exhibited a non-monotonic variation with increasing concentration of FeCl2 solution, is explained from the variation of mass percentage of the maghemite phase with concentration.

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