Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros

Bases de dados
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
Angew Chem Int Ed Engl ; 54(45): 13263-7, 2015 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-26360804

RESUMO

Platinum group metal (PGM) catalysts are the current standard for control of pollutants in automotive exhaust streams. Aside from their high cost, PGM catalysts struggle with CO oxidation at low temperatures (<200 °C) due to inhibition by hydrocarbons in exhaust streams. Here we present a ternary mixed oxide catalyst composed of copper oxide, cobalt oxide, and ceria (dubbed CCC) that outperforms synthesized and commercial PGM catalysts for CO oxidation in simulated exhaust streams while showing no signs of inhibition by propene. Diffuse reflectance IR (DRIFTS) and light-off data both indicate low interaction between propene and the CO oxidation active site on this catalyst, and a separation of adsorption sites is proposed as the cause of this inhibition resistance. This catalyst shows great potential as a low-cost component for low temperature exhaust streams that are expected to be a characteristic of future automotive systems.

2.
Nano Lett ; 13(1): 207-12, 2013 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-23256449

RESUMO

We have established a facile and generalizable "silica-assisted" synthesis for diverse carbon spheres-a category that covers mesoporous carbon nanospheres, hollow mesoporous carbon nanospheres, and yolk-shell mesoporous carbon nanospheres-by using phenolic resols as a polymer precursor, silicate oligomers as an inorganic precursor, and hexadecyl trimethylammoniumchloride as a template. The particle sizes of the carbon nanospheres are uniform and easily controlled in a wide range of 180-850 nm by simply varying the ethanol concentrations. All three types of mesoporous carbon nanospheres have high surface areas and large pore volumes and exhibit promising properties for supercapacitors with high capacitance and favorable capacitance retention.

3.
Angew Chem Int Ed Engl ; 53(12): 3134-7, 2014 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-24677672

RESUMO

The synthesis of mesoporous Prussian blue analogues through a template-free methodology and the application of these mesoporous materials as high-performance cathode materials in sodium-ion batteries is presented. Crystalline mesostructures were produced through a synergistically coupled nanocrystal formation and aggregation mechanism. As cathodes for sodium-ion batteries, the Prussian blue analogues all show a reversible capacity of 65 mA h g-1 at low current rate and show excellent cycle stability. The reported method stands as an environmentally friendly and low-cost alternative to hard or soft templating for the fabrication of mesoporous materials.

4.
J Am Chem Soc ; 135(26): 9572-5, 2013 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-23796254

RESUMO

A template-free synthesis of a hierarchical microporous-mesoporous metal-organic framework (MOF) of zinc(II) 2,5-dihydroxy-1,4-benzenedicarboxylate (Zn-MOF-74) is reported. The surface morphology and porosity of the bimodal materials can be modified by etching the pore walls with various synthesis solvents for different reaction times. This template-free strategy enables the preparation of stable frameworks with mesopores exceeding 15 nm, which was previously unattained in the synthesis of MOFs by the ligand-extension method.


Assuntos
Compostos Organometálicos/síntese química , Ácidos Ftálicos/química , Zinco/química , Modelos Moleculares , Compostos Organometálicos/química , Tamanho da Partícula , Porosidade , Propriedades de Superfície
5.
Nat Commun ; 11(1): 1317, 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-32152286

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

6.
Nat Commun ; 11(1): 1062, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32102998

RESUMO

Supported metal single atom catalysts (SACs) present an emerging class of low-temperature catalysts with high reactivity and selectivity, which, however, face challenges on both durability and practicality. Herein, we report a single-atom Pt catalyst that is strongly anchored on a robust nanowire forest of mesoporous rutile titania grown on the channeled walls of full-size cordierite honeycombs. This Pt SAC exhibits remarkable activity for oxidation of CO and hydrocarbons with 90% conversion at temperatures as low as ~160 oC under simulated diesel exhaust conditions while using 5 times less Pt-group metals than a commercial oxidation catalyst. Such an excellent low-temperature performance is sustained over hydrothermal aging and sulfation as a result of highly dispersed and isolated active single Pt ions bonded at the Ti vacancy sites with 5 or 6 oxygen ions on titania nanowire surfaces.

7.
ChemSusChem ; 8(1): 177-83, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25385481

RESUMO

Hierarchically superstructured Prussian blue analogues (hexacyanoferrate, M=Ni(II) , Co(II) and Cu(II) ) are synthesized through a spontaneous assembly technique. In sharp contrast to macroporous-only Prussian blue analogues, the hierarchically superstructured porous Prussian blue materials are demonstrated to possess a high capacitance, which is similar to those of the conventional hybrid graphene/MnO2 nanostructured textiles. Because sodium or potassium ions are involved in energy storage processes, more environmentally neutral electrolytes can be utilized, making the superstructured porous Prussian blue analogues a great contender for applications as high-performance pseudocapacitors.


Assuntos
Capacitância Elétrica , Ferrocianetos/química , Ferrocianetos/síntese química , Técnicas de Química Sintética , Eletroquímica , Modelos Moleculares , Conformação Molecular , Porosidade
8.
Dalton Trans ; 43(48): 17893-8, 2014 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-25301034

RESUMO

Microporous metal-organic frameworks (MOFs) represent a new family of microporous materials, offering potential applications in gas separation and storage, catalysis, and membranes. The engineering of hierarchical superstructured MOFs, i.e., fabricating mesopores in microporous frameworks during the crystallization stage is expected to serve a myriad of applications for molecular adsorption, drug delivery, and catalysis. However, MOFs with mesopores are rarely studied because of the lack of a simple, effective way to construct mesoscale cavities in the structures. Here, we report the use of a perturbation-assisted nanofusion technique to construct hierarchically superstructured MOFs. In particular, the mesopores in the MOF structure enabled the confinement of large dye species, resulting in fluorescent MOF materials, which can serve as a new type of ratiometric luminescent sensors for typical volatile organic compounds.

9.
Adv Mater ; 24(45): 6017-21, 2012 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-22976113

RESUMO

A "ship-in-a-bottle" approach to the entrapment and assembly of nanometer-sized polymer dots in hollow silica or carbon nanospheres with size-selective micropores is presented. This new type of core-shell nanospheres exhibits excellent photoluminescence properties and significant adsorption capabilities for transition-metal ions.


Assuntos
Carbono/química , Cristalização/métodos , Nanosferas/química , Polímeros/química , Pontos Quânticos , Dióxido de Silício/química , Teste de Materiais , Nanosferas/ultraestrutura , Tamanho da Partícula , Porosidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA