scholarly journals 2D Mesoporous Channels of PMO; a Platform for Cluster-Like Pt Synthesis and Catalytic Activity in Nitrophenol Reduction

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 167 ◽  
Author(s):  
Mohamed Esmat ◽  
Hamed Mohtasham ◽  
Yasser GadelHak ◽  
Reza Tarbiat Mehrebani ◽  
Rafat Tahawy ◽  
...  
Keyword(s):  
Mesoporous Material ◽  
Room Temperature ◽  
Aqueous Media ◽  
Pt Nanoparticles ◽  
Reduction Reaction ◽  
Periodic Mesoporous Organosilica ◽  
High Tunability ◽  
Mesoporous Organosilica ◽  
Efficient Reduction ◽  
Nitrophenol Reduction

Thiourea-bridged organosiloxane is used to synthesize a periodic mesoporous organosilica (PMO). Since this PMO has an S-enriched surface, owing to thiourea functional groups, it exhibits strong coordination toward Pt ions, and it shows a high tunability in the Pt nanoparticles size. This hybrid mesoporous material is employed as a catalyst in the efficient reduction reaction of 4-nitrophenol to 4-aminophenol at room temperature in an aqueous media.

Impact of curing condition on chemical stability of ultralow-k PMO material.

2012 ◽  
Vol 1428 ◽  
Author(s):  
M. B. Krishtab ◽  
L. Zhang ◽  
Q. T. Le ◽  
K. Vanstreels ◽  
L. Souriau ◽  
...  
Keyword(s):  
Thermal Annealing ◽  
Chemical Stability ◽  
Mesoporous Material ◽  
Periodic Mesoporous Organosilica ◽  
Mesoporous Organosilica ◽  
Ring Structures ◽  
Curing Condition ◽  
New Generation ◽  
Low K ◽  
Stable Material

ABSTRACTIn this work a new generation of periodic mesoporous organosilica (PMO) low-k dielectrics with targeted k-values 2.0 and 1.8 is evaluated. In addition, impact of two different curing processes on properties of the mesoporous material is analyzed. It is shown that removal of templating organics with thermal annealing leads to formation of mechanically robust and chemically very stable material, while application of UV-assisted curing with broadband lamp (λ > 200 nm) causes pronounced decrease of film ability to sustain in diluted HF solution. The explanation of that phenomenon is given in terms of silica-ring structures formed within organosilica skeleton.

scholarly journals AuCu@Pt Nanoalloys for Catalytic Application in Reduction of 4-Nitrophenol

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Sadia Mehmood ◽  
Naveed Kausar Janjua ◽  
Farhat Saira ◽  
Hicham Fenniri
Keyword(s):  
Rate Constants ◽  
Room Temperature ◽  
Aqueous Media ◽  
Pure Metal ◽  
Reduction Reaction ◽  
Core Shell ◽  
Metal Shell ◽  
New Class ◽  
Catalytic Application ◽  
Temperature Activation

To enhance and optimize nanocatalyst ability for nitrophenol (4-NP) reduction reaction we look beyond Au-metal nanoparticles and describe a new class of Au nanoalloys with controlled composition for core of AuCu-metals and Pt-metal shell. The reduction of 4-NP was investigated in aqueous media spectroscopically on 7.8 nm Au nanospheres (AuNSs), 8.3 nm AuCuNSs, and 9.1 nm AuCu@Pt core-shell NSs in diameter. The rate constants of the catalyzed reaction at room temperature, activation energies, and entropies of activation of reactions catalyzed by the AuCu@Pt core-shell NSs are found to have different values to those of the pure metal NSs. The results strongly support the proposal that catalysis by nanoparticles is taking place efficiently on the surface of NSs. These core-shell nanocatalysts exhibited stability throughout the reduction reaction and proved that heterogonous type mechanisms are most likely to be dominant in nanoalloy based catalysis if the surface of the NSs is not defected upon shell incorporation.

scholarly journals Highly Active Ruthenium Catalyst Supported on Magnetically Separable Mesoporous Organosilica Nanoparticles

2020 ◽  
Vol 10 (17) ◽  
pp. 5769
Author(s):  
Suheir Omar ◽  
Raed Abu-Reziq
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Direct Method ◽  
Sol Gel ◽  
Reaction Medium ◽  
Ruthenium Oxide ◽  
Reduction Reaction ◽  
Periodic Mesoporous Organosilica ◽  
X Ray ◽  
Mesoporous Organosilica

A facile and direct method for synthesizing magnetic periodic mesoporous organosilica nanoparticles from pure organosilane precursors is described. Magnetic ethylene- and phenylene-bridged periodic mesoporous organosilica nanoparticles (PMO NPs) were prepared by nanoemulsification techniques. For fabricating magnetic ethylene- or phenylene-bridged PMO NPs, hydrophobic magnetic nanoparticles in an oil-in-water (o/w) emulsion were prepared, followed by a sol–gel condensation of the incorporated bridged organosilane precursor (1,2 bis(triethoxysilyl)ethane or 1,4 bis(triethoxysilyl)benzene), respectively. The resulting materials were characterized using high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (XRD), solid-state NMR analysis, and nitrogen sorption analysis (N2-BET). The magnetic ethylene-bridged PMO NPs were successfully loaded using a ruthenium oxide catalyst by means of sonication and evaporation under mild conditions. The obtained catalytic system, termed Ru@M-Ethylene-PMO NPS, was applied in a reduction reaction of aromatic compounds. It exhibited very high catalytic behavior with easy separation from the reaction medium by applying an external magnetic field.

Synthesis of dendrimer-templated Pt nanoparticles immobilized on mesoporous alumina for p-nitrophenol reduction

2015 ◽  
Vol 39 (12) ◽  
pp. 9942-9950 ◽  
Author(s):  
Qianli Wang ◽  
Yiwei Zhang ◽  
Yuming Zhou ◽  
Zewu Zhang ◽  
Yuanmei Xu ◽  
...  
Keyword(s):  
Pt Nanoparticles ◽  
Reduction Reaction ◽  
Mesoporous Alumina ◽  
Nitrophenol Reduction ◽  
Different Temperatures

Dendrimer-templated mesoporous alumina-supported Pt nanocatalysts were prepared and used to catalyze reduction reaction after calcination at different temperatures in nitrogen.

Temperature Dependence of the Self-Assembled Styrene Based Random Ionomers in Aqueous Solution

2003 ◽  
Vol 775 ◽  
Author(s):  
Sung-Hwa Oh ◽  
Ju-Myung Song ◽  
Joon-Seop Kim ◽  
Hyang-Rim Oh ◽  
Jeong-A Yu
Keyword(s):  
Partition Coefficients ◽  
Room Temperature ◽  
Aqueous Media ◽  
The Self ◽  
Spectroscopic Methods ◽  
Ion Content ◽  
Repeat Units ◽  
Notable Effect ◽  
Order Of Magnitude ◽  
Experimental Errors

AbstractSolution behaviors of poly(styrene-co-sodium methacrylate) were studied by fluorescence spectroscopic methods using pyrene as a probe. The mol% of methacrylate was in the range 3.6–9.4. Water and N,N-dimethylforamide(DMF) mixture was used as a solvent (DMF/water = 0.2 mol %). The critical micelle (or aggregation) concentrations of ionomers and the partition coefficients of pyrene were obtained the temperature range 10–80°C. At room temperature, the values of CMCs (or CACs) were in the range 4.7 ×10-6 5.3 ×10-6 g/mL and we could not find any notable effect of the content of ionic repeat units within the experimental errors. Unlike CMCs, as the ion content increased, partitioning of pyrene between the hydrophobic aggregates and an aqueous media decreased from 1.5 ×105 to 9.4 ×104. As the temperature increased from 10 to 80 °C, the values of CMCs increased less than one order of magnitude. While, the partition coefficients of pyrene decreased one order of magnitude and the effect of the ion content became negligible.

Pt Distribution- Controlled Ni-Pt Nanocrystals via Alcohol Reduction Technique for Oxygen Reduction Reaction

2021 ◽  
Author(s):  
Kaneyuki Taniguchi ◽  
Jhon Lehman Cuya Huaman ◽  
Dausuke Iwata ◽  
Shun Yokoyama ◽  
Takatoshi Matsumoto ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Pt Nanoparticles ◽  
Cost Benefit ◽  
Reduction Reaction ◽  
Reduction Technique ◽  
Co Poisoning ◽  
Transition Elements ◽  
Poisoning Effect ◽  
Alcohol Reduction

Alloying Pt with transition elements as electrodes in fuel cells has been proposed to solve the CO poisoning effect besides cost-benefit. Consequently, the use of Ni-Pt nanoparticles (NPs) has been...

Light-harvesting photocatalysis for H2 evolution by methylacridone-bridged periodic mesoporous organosilica

2021 ◽  
Vol 287 ◽  
pp. 119965
Author(s):  
Yasutomo Goto ◽  
Ken-ichi Yamanaka ◽  
Masataka Ohashi ◽  
Yoshifumi Maegawa ◽  
Shinji Inagaki
Keyword(s):  
Light Harvesting ◽  
H2 Evolution ◽  
Periodic Mesoporous Organosilica ◽  
Mesoporous Organosilica
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