Palladium monolayer

Kibler LA, El-Aziz AM, Hoyer R, Kolb DM. 2005. Tuning reaction rates by lateral strain in a palladium monolayer. Angew Chem Int. Ed 44 2080-2084. 

Shao MH, Huang T, Liu P, Zhang J, Sasaki K, Vukmirovic MB, Adzic RR. 2006a. Palladium monolayer and palladium alloy electrocatalysts for oxygen reduction. Langmuir 22 10409-10415. 

Theoretical studies show that bimetallic bonding increases the stability of the Pd 4d valence band [14,23,34,36,40,90,98], The variation in surface core level shifts for metal overlayers is accompanied by a similar shift in the center of gravity of the admetal d band [34,40,90]. In the top panel of Figure 18 is shown the calculated density-of-states (DOS) at the Fermi level for a palladium monolayer on four different metal substrates. As one moves from Pd/Ru to Pd/Ta, there is a substantial... 

Figure 4.32. First scan cyclic voltammogram of Pd(lll) in 0.1 M H2SO4 starting at 0.1 VscE and scanned in the negative direction first. Scan rate 10 mV 298 K [167a]. (Reprinted with permission from Kibler LA, El-Aziz AM, Hoyer R, Kolb DM. Tuning reaction rates by lateral strain in a palladium monolayer. Angew Chem Int Ed 2005 44 2080-4. 2005 German Chemical Society.)...

On the (0001) face of a-alumina covered with one niobium, zirconium, molybdenum, ruthenium or palladium monolayer, Ohuchi and Koyama (1991) have shown that the metal d band is located in the energy range of the alumina gap. It is hybridized with the oxygen states of the valence band. In the series, more and more anti-bonding d states are filled, which yields results in agreement with the cluster calculations quoted above. 

Zamborini, F.P., Gross, S.M. and Murray, R.W. (2001) Synthesis, characterization, reactivity, and electrochemistry of palladium monolayer proteded clusters. Lar muir, 17, 481. 

Electroless reactions must be autocatalytic. Some metals are autocatalytic, such as iron, in electroless nickel. The initial deposition site on other surfaces serves as a catalyst, usually palladium on noncatalytic metals or a palladium—tin mixture on dielectrics, which is a good hydrogenation catalyst (20,21). The catalyst is quickly covered by a monolayer of electroless metal film which as a fresh, continuously renewed clean metal surface continues to function as a dehydrogenation catalyst. Silver is a borderline material, being so weakly catalytic that only very thin films form unless the surface is repeatedly cataly2ed newly developed baths are truly autocatalytic (22). In contrast, electroless copper is relatively easy to maintain in an active state commercial film thicknesses vary from <0.25 to 35 p.m or more. 

Figure 2 Surface EXAFS spectra above the Pd L edge for a 1.5 monolayer evaporated film of Pd on Sid 11) and for bulk palladium ailicide, Pd2Si and metallic Pd.

Size-selected palladium atoms were deposited on an in. sv /M-prepared MgO(lOO) thin film at 90 K the palladium surface concentration was about 1% of a monolayer. Comparison of ab initio calculations and FTIR studies of CO adsorption provided evidence for single Pd atoms bond to F centres of the MgO support with two CO molecules attached to each palladium atom.24... 

The surface areas of the iridium and palladium catalysts were determined by chemisorption of hydrogen and carbon monoxide, respectively, the monolayer volume being determined from an adsorption isotherm taken at 20°C. 

Xu, T., Zach, M.P., Xiao, Z.L., Rosenmann, D., Welp, U., Kwok, W.K. and Crabtree, G.W., Self-assembled monolayer-enhanced hydrogen sensing with ultra thin palladium films, Applied Physics Letters, 86, 203104, 2005. 

Kaifer and coworkers showed interest in the modification of metal nanoparticles with organic monolayers prepared with suitable molecular hosts. They reported the preparation of water-soluble platinum and palladium nanoparticles modified with thiolated /1-cyclodexlrin (/ -CD) [69]. Nanoparticle synthesis was... 

The high sensitivity of tunneling spectroscopy and absence of strong selection rules allows infrared and Raman active modes to be observed for a monolayer or less of adsorbed molecules on metal supported alumina. Because tunneling spectroscopy includes problems with the top metal electrode, cryogenic temperatures and low intensity of some vibrations, model catalysts of evaporated metals have been studied with CO and acetylene as the reactive small molecules. Reactions of these molecules on rhodium and palladium have been studied and illustrate the potential of tunneling spectroscopy for modeling reactions on catalyst surfaces,... 

In a series of papers, Kolb and coworkers have presented CV and in situ STM studies on palladium deposition on various gold single-crystal electrodes. They have found [430] that PdCU is adsorbed on Au(lll), forming a distorted hexagonal structure, which plays a crucial role in Pd deposition and dissolution. It has also been found that Pd deposition starts from the formation of a pseudomorphic layer in the underpotential region, followed by the formation of the second Pd monolayer at overpotentials. Pd nucleated... 

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