Chemical Vapor Deposition of Platinum, Palladium and Nickel

The synthesis and characterization of palladium-grafted mesoporous MCM-41 material, designated Pd-TMS11, are described. The material is investigated for carbon−carbon coupling reactions (Heck catalysis) with activated and nonactivated aryl substrates. For the preparation of the new catalyst, a volatile organometallic precursor is reacted in the gas phase with the surface of the porous framework, generating a highly dispersed metal deposition. The ultrahigh surface area, the large pore opening, and the highly dispersed catalyst species in Pd-TMS11 material create one of the most active heterogeneous catalysts for Heck reactions.

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“…Therefore, a different approach was adopted that involved introduction of palladium species from the vapor phase …”

Section: Resultsmentioning

confidence: 99%

Heterogeneous Heck Catalysis with Palladium-Grafted Molecular Sieves

1998

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“…A number of enhancement methods have been developed for CVD processes, and among them is catalyst-enhanced CVD (CECVD), in which co-deposition of a catalytically active metal such as palladium can enhance the CVD of other materials . The basis is that palladium is a highly active catalyst for hydrogenation and oxidation and also yields a very active surface for CVD. ,, The complex [Pd(η 3 -2-methylallyl)(acac)], 7 , (acac = acetylacetonate) is particularly useful for catalyst- enhanced CVD and was used in the following experiments …”

Section: Resultsmentioning

confidence: 99%

Chemical Vapor Deposition of Tantalum Oxide from Tetraethoxo(β-diketonato)tantalum(V) Complexes

Pollard

Puddephatt

1999

Chem. Mater.

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The complexes [Ta(OEt) 4 (β-diketonate)] (β-diketonate ) acetylacetonate, 2; hexafluoroacetylacetonate , 3; 1,1,1-trifluoroacetylacetonate, 4; dipivaloylmethanate, 5; 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionate, 6) are established as volatile liquid precursors for low-pressure chemical vapor deposition (CVD) of films of tantalum(V) oxide. They give thermal CVD at a slightly lower temperature than the commonly used precursor [{Ta-(OEt) 5 } 2 ], 1. In all cases, the CVD at 300-450 °C gives amorphous films of Ta 2 O 5 , which crystallize on annealing at 800 °C under oxygen. Promotion of Ta 2 O 5 film formation is established using catalyst-enhanced CVD with a palladium precursor as "catalyst" and the minimum CVD temperature is then reduced to 200 °C.

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“…A number of enhancement methods have been developed for chemical vapor deposition (CVD) processes, and these may serve either to lower the temperature of the CVD process, thus allowing films to be grown on thermally sensitive substrates, or to improve the purity of the deposited films. Common enhancement methods include the use of reactive carrier gases, photochemical irradiation using standard UV sources, lasers or synchrotron radiation, ion beams, and plasmas. , It is also well-known that some CVD processes in which catalytically active metals are deposited may be autocatalytic and that seeding a surface with an active metal may promote selective CVD on the seeded areas, particularly if a reactive carrier gas such as hydrogen or oxygen is also used. − It is thought that the catalytically active metal acts as a reactive site for adsorption and dissociation of the CVD precursor and, in the presence of a reactive carrier gas oxygen or hydrogen, greatly facilitates removal of ligand fragments from the surface by catalytic oxidation or reduction, respectively. − In turn, this regenerates a clean surface for further precursor adsorption and decomposition. If this interpretation is correct, it seemed possible that catalysis of the CVD of a noncatalytic material might occur by co-deposition (rather than pre-deposition as in the prior literature described above) of a catalytically active material.…”

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confidence: 99%

“…Previous studies have shown that CVD of palladium can be enhanced by use of either hydrogen or oxygen as reactive carrier gases and can be very surface-selective. , In addition, it is known that palladium is a highly active catalyst for both hydrogenation and oxidation and that it yields a very active surface for CVD of other metals. , Palladium was therefore chosen as the catalyst component for CECVD, and although several precursors have been shown to have catalytic activity, the complexes [Pd(η 3 -2-methylallyl)(acac)] ( 1 , acac = acetylacetonate) 4 and [Pd(hfac) 2 ] ( 2 , hfac = hexafluoroacetylacetonate) 5 have been shown to be particularly useful for CECVD under oxidative or reductive conditions, respectively.

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mentioning

confidence: 99%