Palladium coatings

Palladium and gold Palladium electrodeposition is of special interest for catalysis and for nanotechnology. It has been reported [49] that it can be deposited from basic chloroaluminate liquids, while in the acidic regime the low solubility of PdCl2 and passivation phenomena complicate the deposition. In our experience, however, thick Pd layers are difficult to obtain from basic chloroaluminates. With different melt compositions and special electrochemical techniques at temperatures up to 100 °C we succeeded in depositing mirror-bright and thick nanocrystalline palladium coatings [10]. 

Lid of palladium or steel wfth Internal palladium coating... 

Apparatus can also be constructed from TRIM which consists of palladium coated with ZGS platinum this permits the production of stouter apparatus with the corrosion resistance of ZGS platinum at an appreciably cheaper price. 

Wang, Z.F., Xiao, P.F., Shen, B. and He, N.Y. (2006) Synthesis of palladium-coated magnetic nanoparticle and its application in Heck reaction. Colloids and Surfaces A Physicochemical and Engineering Aspects, 276 (1-3), 116-121. 

Buxbaum, R.E. and T.L. Marker, Hydrogen transport through non-porous membranes of palladium-coated niobium, tantalum and vanadium. /. Membr. Sci., 85, 29-38,1993. 

Hara, S., N. Hatakeyama, N. Itoh, H.-M. Kimura, and A. Inoue, Hydrogen permeation through palladium-coated amorphous Zr-M-Ni (M=Ti, Hf) alloy membranes, Desalination, 144,115-120, 2002. 

There are three major classes of palladium-based hydrogen sensors [4], The most popular class of palladium-based sensors is based on palladium resistors. A thin film of palladium deposited between two metal contacts shows a change in conductivity on exposure to hydrogen due to the phase transition in palladium. The palladium field-effect transistors (FETs) or capacitors constitute the second class, wherein the sensor architecture is in a transistor mode or capacitor configuration. The third class of palladium sensors includes optical sensors consisting of a layer of palladium coated on an optically active material that transforms the hydrogen concentration to an optical signal. 

Cassidy, J., Pons, S. and Janata, J., Hydrogen response of palladium coated suspended gate field effect transistor, Analytical Chemistry, 58(8), 1757,1986. 

Zalvidea, D., Diez, A., Cruz, J.L. and Andres, M.V., A wavelength multiplexed hydrogen sensor based on a palladium-coated fibre taper and a Bragg grating, Electron, 40, 301, 2004. 

A different approach was followed by Blackledge et al. [124]. They used the catalytic activity of a palladium coated SPM-tip to selectively generate a pattern into different co-functionalized SAMs. 

Zhang and Wang (1997) studied the reaction of zero-valent iron powder and palladium-coated iron particles with trichloroethylene and PCBs. In the batch scale experiments, 50 pL of 200 pg/mL PCB-1254 in methanol was mixed with 1 ml ethanol/water solution (volume ratio = 1/9) and 0.1 g of wet iron or palladium/iron powder in a 2-mL vial. The vial was placed on a rotary shaker (30 rpm) at room temperature for 17 h. Trichloroethylene was completely dechlorinated by the nanoscale palladium/iron powders within the 17-h time period. Only partial dechlorination of PCB-1254 was observed when wet iron powder was used. 

The scanning electron microscopy micrographs shown in the body of this manuscript were taken by AMR-1000 and Jeol C-35 instruments. All specimens were gold-palladium coated. To obtain the cross-section morphologies, the membranes were fragmented in liquid nitrogen. 

Nanosized cobalt, copper, gold, nickel, rhodium, and silver particles have been stabilized by polyions and polymers [514, 549-553]. Particularly significant has been the simultaneous reduction of HAuC14 and PdCl2 in the presence of poly(iV-vinyl-2-pyrrolidine) to give relatively uniform, 1.6-nm-diameter, palladium-coated gold bimetallic clusters [554]. 

R.E. Buxbaum and T.L. Marker, Hydrogen Transport Through Non-porous Membranes of Palladium-coated Niobium, Tantalum, and Vanadium, 7. Membr. Sci. 85, 29 (1993). 

R.E. Buxbaum and A.B. Kinney, Hydrogen Transport Through Tubular Membranes of Palladium-coated Tantalum and Niobium, Ind. Eng. Chem. Res. 35, 530 (1996). 

Gold/palladium-coated nanospray capillaries (Protana) or a PicoTip emitter (New Objective). 

For nano-ESI-MS MS , the sample is loaded either in a previously rinsed gold/palladium-coated nanospray capillary (Promega) or in a PicoTip emitter (New Objective) and analyzed in a nanospray source. 

Scheme 4.63 Reduction using palladium-coated capillaries.

A palladium-coated glass capillary could be prepared by heating a solution of Pd(OAc)2 at 1500 C for 30 min within the tube to deposit a layer of Pd(0). The capillary was further heated to 350 °C for three cycles of 1 min to improve the porosity of the... 

Buxbaum R.E., Kinney A.V. Hydrogen transport through tubular membranes of palladium-coated tantalum and niobium. Ind.Eng.Chem.Res. 1996 35 530-537. 

The nature of the cathode has been found to have major effect on the efficiency of electrochemical HDH of halogenated compounds. For instance, the HDH of 12 mM chlorobenzene at carbon cloth or lead cathodes gave conversions up to 95% with a current efficiency of 20%, lower conversion and efficiency (<5%) were observed using platinum, titanium or nickel cathodes (Zanaveskin et al. 1996). A 100% electrochemical HDH of 153 ppm 4-chlorophenol to phenol was achieved using a palladium-coated carbon cloth cathode (Balko et al. 1993). Unfortunately, several environmentally unacceptable materials, such as Hg and Pb, have also been used as cathodes (Bonfatti et al. 1999 Kulikov et al. 1996). 

R.E. Buxbaum, R. Subramanian, J.H. Park, and D L. Smith, Hydrogen Transport and Embrittlement for Palladium Coated Vanadium-Chromium-Titanium Alloys, Journal of Nuclear Material, Part A, 233-237, 1996, pp.510-512. 

Hsu, C., and RP. Buxbaum, 1987, Palladium-coated zirconium membranes for oxidative extraction, in Preprint Annual AIChE Meeting, New York. 

The first commercial metal membranes for hydrogen separation and purification were made of palladium alloyed with 23-25 wt % silver. These membrane were of the unsupported type and tubular in shape. Nevertheless, the wall thickness was substantial by current standards—typically at least 100- an thick. Advances in drawing thin-walled metal tubes has allowed for palladium-silver tubular membranes to be made with much thinner walls, about 20- an thick. Composite membranes are also usually at least 25-/an thick. REB Research and Consulting (Oak Park, MI) provides tubular composite metal membranes consisting of a palladium coating over a tantalum base metal, although other group 4 or 5 base metals may be used. 

Electroless deposition can successfully be used in the production of various composite materials useful for the electronics applications. The examples include silver-coated copper or nickel particles, used in screen printing,43 gold-coated nickel powders, silver and/or palladium-coated polymers or glass powders used in ball grid array, etc. 

Leung, L.-W.H. and Weaver, M.J. (1987) Extending surface-enhanced Raman spectroscopy to transition-metal surfaces carbon monoxide adsorption and electrooxidation on platinum- and palladium-coated gold electrodes. Journal of the American Chemical Society, 109, 5113-5119. 

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