Fabrication of platinum nanoparticles and nanowires by electron beam lithography (EBL) and nanoimprint lithography (NIL): comparison of ethylene hydrogenation kinetics

Contreras, A. M.; Grunes, Jeff; Yan, Xiaoming; Liddle, A.; Somorjai, Gábor A.

doi:10.1007/s10562-004-3436-7

Cited by 51 publications

(50 citation statements)

References 33 publications

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“…The CO-poisoned activation energy for ethylene hydrogenation on alumina and silica is 11.4 and 15.6 kcal͞ mol, respectively (17). These values are much lower than for the Pt single crystal.…”

Section: Reactivity Of Oxide-metal Interfacesmentioning

confidence: 86%

See 1 more Smart Citation

Clusters, surfaces, and catalysis

Somorjai¹,

Contreras

Montano

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

245

187

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The surface science of heterogeneous metal catalysis uses model systems ranging from single crystals to monodispersed nanoparticles in the 1-10 nm range. Molecular studies reveal that bond activation (C-H, H-H, C-C, CAO) occurs at 300 K or below as the active metal sites simultaneously restructure. The strongly adsorbed molecules must be mobile to free up these sites for continued turnover of reaction. Oxide-metal interfaces are also active for catalytic turnover. Examples using C-H and CAO activation are described to demonstrate these properties. Future directions include synthesis, characterization, and reaction studies with 2D and 3D monodispersed metal nanoclusters to obtain 100% selectivity in multipath reactions. Investigations of the unique structural, dynamic, and electronic properties of nanoparticles are likely to have major impact in surface technologies. The fields of heterogeneous, enzyme, and homogeneous catalysis are likely to merge for the benefit of all three.catalytic bond activation ͉ high selectivity catalyst design ͉ molecular ingredients of catalysis M etal containing catalysts are clusters of 1-10 nm in size. These are grouped into three types: heterogeneous catalysts that are embedded in high surface area supports, usually oxides, to optimize their surface area and thus the number of molecules they produce per second and also to optimize their thermal and chemical stability. They are used mostly at high temperatures (400-800 K) and in the presence of vapor phase reactants and product molecules. Enzyme catalysts operate in solution, mostly in water near 300 K, and the metal-containing active sites are surrounded by proteins that maintain structural mobility (1). Homogeneous catalysts function in the same solution in which the reactant and product molecules are dissolved, mostly in organic solvents, and used in the 300-500 K temperature range. Because of the different operating conditions and for reasons of history, the three fields of catalysis developed independently and became separate fields of science within different subdisciplines of chemistry. Heterogeneous catalysis was practiced mostly by physical chemists and chemical engineers, enzyme catalysis by biochemists, and homogeneous catalysis by inorganic and organometallic chemists.Catalytic reactions are distinguished from stoichiometric reactions by having many turnovers per reacting active site producing 10 2 to 10 6 molecules per site. Some of these catalytic reactions are very fast. For instance, the catalytic oxidation of carbon monoxide (CO) produces thousands of CO 2 molecules per metal surface site per second above ignition where the exothermicity of the process makes it self-sustaining in temperature and the reaction rate is only limited by the speed of transport of molecules to and from the catalyst surface (2-4). Ethylene hydrogenation, another exothermic reaction, turns over to produce ethane Ϸ10 times per metal surface site per second at 300 K on Pt(111) (5). The catalytic conversion of n-hexane to benzene or to branched...

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Section: Reactivity Of Oxide-metal Interfacesmentioning

confidence: 86%

“…This field developed rapidly by use of model catalysts, first single-crystal surfaces (7)(8)(9)(10)(11)(12), then monodispersed nanoclusters deposited on oxide surfaces by lithography techniques (13)(14)(15)(16)(17) (Fig. 1).…”

mentioning

confidence: 99%

Clusters, surfaces, and catalysis

Somorjai¹,

Contreras

Montano

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

245

187

View full text Add to dashboard Cite

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“…Similar results were also reported over Pt NP arrays and nanowires. 16,17 For supported Pt NPs, TOFs (after correcting to our standard conditions in the same way as above) of 12 to 18 18 , 2 to 4 19 , 0.5 8 , 3 9 , 9 to 11 20 s -1 have been reported. Therefore, the WI prepared Pt and PVP capped Pt (when pretreated at 200°C and below) displayed TOFs in the range described as typical.…”

Section: Ethylene Hydrogenation Activitymentioning

confidence: 96%

“…Based on the literature for Pt single crystals [13][14][15] , traditionally prepared supported Pt catalysts 18,19 , supported Pt nanoparticles 9,20 , Pt NP arrays 16,17 , and Pt nanowires 16 , an average TOF (after being corrected to the conditions reported in this paper in the same manner as described in Section 3.2) was 8.7 s -1 . Using this value as a normalization factor, dispersions were estimated from ethylene hydrogenation as a chemical probe technique (Table 2).…”

Section: Estimation Of Metallic Surface Area By Ethylene Hydrogenationmentioning

confidence: 98%

Effect of organic capping layers over monodisperse platinum nanoparticles upon activity for ethylene hydrogenation and carbon monoxide oxidation

Kuhn

Tsung

Huang

et al. 2009

Journal of Catalysis

171

150

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The influence of oleylamine (OA), trimethyl tetradecyl ammonium bromide (TTAB), and polyvinlypyrrolidone (PVP) capping agents upon the catalytic properties of Pt/silica catalysts was evaluated. Pt nanoparticles of 1.5 nm in size were synthesized by the same procedure (ethylene glycol reduction under basic conditions) with the various capping agents added afterwards for stabilization.Before examining catalytic properties for ethylene hydrogenation and CO oxidation, the Pt NPs were deposited onto mesoporous silica (SBA-15) supports and characterized by transmission electron microscopy (TEM), H 2 chemisorption, and elemental analysis (ICP-MS). PVP and TTAB capped Pt yielded mass normalized reaction rates that decreased with increasing pretreatment temperature and was attributed to partial coverage of the Pt surface with decomposition products from the organic capping agent. Once normalized to the Pt surface area, similar intrinsic activities were obtained regardless of the pretreatment temperature, which indicated no influence on the nature of active sites. Consequently, a chemical probe technique using intrinsic activity for ethylene hydrogenation was demonstrated as an acceptable method for estimating the metallic surface areas of Pt. Amine (OA) capping exhibited a detrimental influence on the catalytic properties as severe deactivation and low activity were observed for ethylene hydrogenation and CO oxidation, respectively. These results were consistent with amine groups being strong poisons for Pt surfaces and revealed the need to consider the effects of capping agents to stabilize nanoparticles on the catalytic properties.

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“…22 Nanowire length is controlled by the reaction time. Finally, spatial registration of these nanowires can be achieved by controlling the position of the nanoparticles ( Figure S1, Supporting Information), as well as using other methods including nanoimprint lithography [23][24][25] and e-beam lithography. 26 As a result, the dimensions and positioning of the vertical nanowires can be accurately controlled to create suitable substrates for VINFET fabrication.…”

mentioning

confidence: 99%

Silicon Vertically Integrated Nanowire Field Effect Transistors

et al. 2006

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Silicon nanowires have received considerable attention as transistor components because they represent a facile route toward sub-100-nm single-crystalline Si features. Herein we demonstrate the direct vertical integration of Si nanowire arrays into surrounding gate field effect transistors without the need for postgrowth nanowire assembly processes. The device fabrication allows Si nanowire channel diameters to be readily reduced to the 5-nm regime. These first-generation vertically integrated nanowire field effect transistors (VINFETs) exhibit electronic properties that are comparable to other horizontal nanowire field effect transistors (FETs) and may, with further optimization, compete with advanced solid-state nanoelectronic devices.

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Fabrication of platinum nanoparticles and nanowires by electron beam lithography (EBL) and nanoimprint lithography (NIL): comparison of ethylene hydrogenation kinetics

Cited by 51 publications

References 33 publications

Clusters, surfaces, and catalysis

Clusters, surfaces, and catalysis

Effect of organic capping layers over monodisperse platinum nanoparticles upon activity for ethylene hydrogenation and carbon monoxide oxidation

Silicon Vertically Integrated Nanowire Field Effect Transistors

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