scholarly journals A Mini Review on Yolk-Shell Structured Nanocatalysts

2020 ◽  
Vol 8 ◽  
Author(s):  
Xiaohuan Sun ◽  
Jie Han ◽  
Rong Guo
Keyword(s):  
Mass Transfer ◽  
Shell Structure ◽  
Material Science ◽  
Synergistic Effects ◽  
Catalytic Performance ◽  
Synthetic Methods ◽  
Great Promise ◽  
Confined Space ◽  
Hollow Shell

Yolk-shell structured nanomaterials, possessing a hollow shell and interior core, are emerging as unique nanomaterials with applications ranging from material science, biology, and chemistry. In particular, the scaffold yolk-shell structure shows great promise as a nanocatalyst. Specifically, the hollow shell offers a confined space, which keeps the active yolk from aggregation and deactivation. The inner void ensures the pathway for mass transfer. Over the last few decades, many strategies have been developed to endow yolk-shell based nanomaterials with superior catalytic performance. This minireview describes synthetic methods for the preparation of various yolk-shell nanomaterials. It discusses strategies to improve the performance of yolk-shell catalysts with examples for engineering the shell, yolk, void, and related synergistic effects. Finally, it considers the challenges and prospects for yolk-shell nanocatalysts.

scholarly journals Synthesis and Characterization of Electrodeposited C-PANI-Pd-Ni Composite Electrocatalyst for Methanol Oxidation

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
S. S. Mahapatra ◽  
S. Shekhar ◽  
B. K. Thakur ◽  
H. Priyadarshi
Keyword(s):  
Methanol Oxidation ◽  
Electrocatalytic Activity ◽  
Electrochemical Impedance ◽  
Synergistic Effects ◽  
Catalytic Performance ◽  
Charge Transfer Resistance ◽  
Pani Film ◽  
Composite Electrodes ◽  
Transfer Resistance ◽  
Onset Potential

Electropolymerization of aniline at the graphite electrodes was achieved by potentiodynamic method. Electrodeposition of Pd (C-PANI-Pd) and Ni (C-PANI-Ni) and codeposition of Pd-Ni (C-PANI-Pd-Ni) microparticles into the polyaniline (PANI) film coated graphite (C-PANI) were carried out under galvanostatic control. The morphology and composition of the composite electrodes were obtained using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques. The electrochemical behavior and electrocatalytic activity of the electrode were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) methods in acidic medium. The C-PANI-Pd-Ni electrode showed an improved catalytic performance towards methanol oxidation in terms of lower onset potential, higher anodic oxidation current, greater stability, lower activation energy, and lower charge transfer resistance. The enhanced electrocatalytic activity might be due to the greater permeability of C-PANI films for methanol molecules, better dispersion of Pd-Ni microparticles into the polymer matrixes, and the synergistic effects between the dispersed metal particles and their matrixes.

scholarly journals Designing a Mesoporous Zeolite Catalyst for Products Optimizing in n-Decane Hydrocraking

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 766 ◽  
Author(s):  
Li Tan ◽  
Xiaoyu Guo ◽  
Xinhua Gao ◽  
Noritatsu Tsubaki
Keyword(s):  
Mass Transfer ◽  
Active Sites ◽  
Zeolite Catalyst ◽  
Catalytic Performance ◽  
Hydrogen Spillover ◽  
Mesoporous Zeolite ◽  
Mesoporous Catalyst ◽  
Hydrogen Atoms ◽  
Effect Factors ◽  
And Diffusion

Mesoporous ZSM-5 zeolite is developed to enhance the catalytic performance in a hydrocracking reaction. The generated mesopores and mesoporous channels in the new catalyst supply more opportunities for reactant accessing the active sites according to the better mass transfer and diffusion. Meanwhile, the acidity of the mesoporous catalyst is also weakened because of the removal of Si and Al species from its MFI structure, which makes the products distribution drift to more valued chemicals such as olefins. In the modified mesoporous ZSM-5 zeolites via different metallic promoters, the olefins’ selectivity increases as the alkalinity of the catalyst increases. The reason for this is that the formed olefins will be further hydrogenated into corresponding alkanes immediately over the extremely acidic zeolite catalyst. Hence, the moderate alkalinity will limit this process, while at the same time the remaining olefins products will too. Furthermore, the Pd-based mesoporous ZSM-5 zeolite shows an excellent n-decane conversion and high propane selectivity due to the occurrence of hydrogen spillover via the Pd promoter. The phenomenon of hydrogen spillover supplies more chemisorbed sites of hydrogen atoms for hydrocracking and hydrogenating in this reaction. In short, this study explores the important effect factors in n-decane hydrocracking reaction activity and products distribution. It also shows a potential for the further industrial application of petroleum-derived fuel hydrocracking according to the optimized products distribution under metallic promoted mesoporous zeolite.

scholarly journals Rationally designed indium oxide catalysts for CO2 hydrogenation to methanol with high activity and selectivity

2020 ◽  
Vol 6 (25) ◽  
pp. eaaz2060 ◽  
Author(s):  
Shanshan Dang ◽  
Bin Qin ◽  
Yong Yang ◽  
Hui Wang ◽  
Jun Cai ◽  
...  
Keyword(s):  
Density Functional ◽  
Rational Design ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Oxide Catalysts ◽  
Great Promise ◽  
Experimental Realization ◽  
Successful Case ◽  
Catalytic Stability ◽  
Pure Phases

Renewable energy-driven methanol synthesis from CO2 and green hydrogen is a viable and key process in both the “methanol economy” and “liquid sunshine” visions. Recently, In2O3-based catalysts have shown great promise in overcoming the disadvantages of traditional Cu-based catalysts. Here, we report a successful case of theory-guided rational design of a much higher performance In2O3 nanocatalyst. Density functional theory calculations of CO2 hydrogenation pathways over stable facets of cubic and hexagonal In2O3 predict the hexagonal In2O3(104) surface to have far superior catalytic performance. This promotes the synthesis and evaluation of In2O3 in pure phases with different morphologies. Confirming our theoretical prediction, a novel hexagonal In2O3 nanomaterial with high proportion of the exposed {104} surface exhibits the highest activity and methanol selectivity with high catalytic stability. The synergy between theory and experiment proves highly effective in the rational design and experimental realization of oxide catalysts for industry-relevant reactions.

scholarly journals Developing two-dimensional solid superacids with enhanced mass transport, extremely high acid strength and superior catalytic performance

2019 ◽  
Vol 10 (23) ◽  
pp. 5875-5883 ◽  
Author(s):  
Fujian Liu ◽  
Xianfeng Yi ◽  
Wei Chen ◽  
Zhiqiang Liu ◽  
Wei Chen ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Mass Transport ◽  
Biomass Conversion ◽  
Catalytic Performance ◽  
Acid Strength ◽  
Two Dimensional ◽  
Solid Superacids ◽  
High Acid ◽  
Transfer Properties

2D hybrid solid superacids with extremely high acid strength and outstanding mass transfer properties were prepared and exhibit superior activities for biomass conversion.

scholarly journals Phenylureas CPPU and Thidiazuron Affect Yield Components, Fruit Composition, and Storage Potential of Four Seedless Grape Selections

1992 ◽  
Vol 117 (1) ◽  
pp. 85-89 ◽  
Author(s):  
A.G. Reynolds ◽  
D.A. Wardle ◽  
C. Zurowski ◽  
N.E. Looney
Keyword(s):  
Synergistic Effects ◽  
Titratable Acidity ◽  
Great Promise ◽  
Table Grapes ◽  
Fruit Composition ◽  
Subsequent Trial ◽  
Berry Weight ◽  
Low Concentrations ◽  
Seedless Grape ◽  
And Storage

One of three levels (O, 1, 10 mg·liter-1) of the cytokinin-active substituted phenylurea compound CPPU was applied with or without 100 mg GA/liter to developing clusters of `Sovereign Coronation' and Summerland Selection 495 grapes (Vitis spp.). In a similar experiment, one of three levels (0, 1, 10 mg·liter-) of either CPPU or the related compound thidiazuron was applied to `Simone' and Summerland Selection 535. Both phenylurea chemicals tended to linearly increase cluster weight and berry weight while reducing degrees Brix, pH, and anthocyanins and increasing titratable acidity. A subsequent trial with O, 4, and 8 mg thidiazuron/liter on all four varieties yielded similar results. GA had no individual or synergistic effects. Due to the very low concentrations required, CPPU and thidiazuron show great promise as chemical tools for the increase of berry weight in seedless table grapes. Chemical names used: N-(2-chloro-4-pyridyl) -N'-phenylurea (CPPU); N1-phenyl-N'-l,2,3-thiadiazol-5-yl urea (thidiazuron);

scholarly journals Nanosecond photochemically promoted click chemistry for enhanced neuropeptide visualization and rapid protein labeling

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Gongyu Li ◽  
Fengfei Ma ◽  
Qinjingwen Cao ◽  
Zhen Zheng ◽  
Kellen DeLaney ◽  
...  
Keyword(s):  
Click Chemistry ◽  
Protein Identification ◽  
Biological Significance ◽  
Great Promise ◽  
Ionization Mass ◽  
Confined Space ◽  
General Applicability ◽  
Tissue Samples ◽  
On Demand ◽  
Lysine Residues

Abstract Comprehensive protein identification and concomitant structural probing of proteins are of great biological significance. However, this is challenging to accomplish simultaneously in one confined space. Here, we develop a nanosecond photochemical reaction (nsPCR)-based click chemistry, capable of structural probing of proteins and enhancing their identifications through on-demand removal of surrounding matrices within nanoseconds. The nsPCR is initiated using a photoactive compound, 2-nitrobenzaldehyde (NBA), and is examined by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). Benefiting from the on-demand matrix-removal effect, this nsPCR strategy enables enhanced neuropeptide identification and visualization from complex tissue samples such as mouse brain tissue. The design shows great promise for structural probing of proteins up to 155 kDa due to the exclusive accessibility of nsPCR to primary amine groups, as demonstrated by its general applicability using a series of proteins with various lysine residues from multiple sample sources, with accumulated labeling efficiencies greater than 90%.

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