Electrocatalysis by electrodeposited spherical platinum microparticles dispersed in a polymeric film electrode

Abstract

473by electron exchange between the adjacent redox centers. Whichever explanation is correct, the new design of electrode should allow electrochemical ESR to be used first to study shorter lived intermediates and second to study intermediates and products in the kinetics of modified electrodes. Experimental SectionThe ESR spectrometer used was a Bruker ER 200 tt. The spectrometer has a dual cavity. In the second cavity a solid solution of Mn2+ in MgO serves as a permanent standard to calibrate the sensitivity of the spectrometer. The flow system and the method of construction of the tube electrode have been described previously.6 The nonelectroactive part of the semiannular or the missing sector electrodes was made of Teflon and assembled in the same way as a complete annular electrode. Except where stated, all chemicals and reagents were of AnalaR grade. Dimethylsulfoxide (BDH) was purified and dried as described previously.I6 Acetonitrile (Fison's dried distilled) was refluxed with 1% (w/v) CaH2 for 2 h and then fractionally distilled. TEAP (Fluka, purum) was recrystallized once from water. TBAT (Fluka, purum) was recrystallized once from a mixture of ethanol and petroleum ether. TMPD (BDH, L. R. grade) was recrystallized as described by Michaelis." Poly(nitro-(16) Mann, C. K. Electroanal. Chem. 1969, 4, 57. (17) Michaelis, L.; Schubert, M. P.; Granick, S. J. Am. Chem. Soc. 1939, 61, 1981.styrene) was synthesized by the method of Wiley and Smith.'* It was coated on to the platinum tube electrode by using the method of Miller.'3Vinylanthraquinone was synthesized by the method of Manecke and Storck.I9 The monomer was polymerized by using benzoyl peroxide initiator in tolulene solution at 100 'C for 240 h. The modified electrode was made by dip coating the platinum electrode in a 1 % (w/v) solution of polymer in CH2C12.All electrochemical experiments were controlled by a purpose built potentiostat of modular construction. Acknowledgment. W e thank the SERC and the WolfsonFoundation for financial support. W e are grateful to Mr. Michael Pritchard for his assistance in making the electrodes, to Mr. John Hooper for constructing the potentiostat, to Dr. S. Wilson for synthesizing poly(nitrostyrene), and to Mr. S. Jawaid for synthesizing poly(viny1anthraquinone). This is a contribution from the Wolfson Unit for Modified Electrodes.Registry No. Pt, TMPD, TMPD radical cation,, 24936-54-7; poly@-nitrostyrene) radical anion, 87842-91-9; poly(2-vinylanthraquinone), 73546-39-1; poly-(2-vinylanthraquinone) radical anion, 87842-93-1.Abstract: Electrochemical methods for the dispersion of Pt microparticles at microgram levels in polymeric matrices of poly(viny1acetic acid) glassy carbon electrodes, Pt-PVAA/GC, are described. The PVAA film was formed on a GC surface by refluxing neat VAA monomer under nitrogen. Cyclic voltammetry and single and double potential step electrolysis were

Metal Oxides as Possible Faradaic Pseudo-Reference Electrodes

“…The fabrication of the Pt-PVAA/ GC electrode has been previously described. 4 Of the various electrodes just described, only the Pt, DSA, composite Ru02, and Pt-PVAA/ GC exhibited sufficiently promising properties to warrant further examination as reported herein.…”

Hidrogenação de compostos orgânicos utilizando método eletroquímico para geração de hidrogênio in situ: hidrogenação eletrocatalítica

“…A HEC pode ocorrer através da imobilização de micropartículas metálicas dispersas dentro de diversos polímeros que podem ser utilizados para preparação do eletrodo modificado, visando a geração de hidrogênio via fotoquímica ou eletroquímica: poli(ácido vinil acético) 47 , poli(3-metiltiofeno) 48 , poli(4-vinilpiridina) 49 , Nafion 50 , polianilina 51 , poli(mercapto-hidroquinona ou benzoquinona) 52 . Outros trabalhos relatam eletrodos modificados contendo partículas de Pt, Pd e Rh utilizando como polímero suporte poli(pirrolviologênio) [53][54][55] , poli(pirrol hidrogenosulfato) 56 ou mesmo o uso de micropartículas de Ni dispersas em poli(pirrol alquilamônio) 46 .…”

Simulation of edge effects in electroanalytical experiments by orthogonal collocation. Part V. Chronoamperometry at ultramicroelectrode ensembles

“…Work has proceeded on a variety of ultramicroelectrode array geometries, including cross sections of epoxy embedded reticulated carbon arrays (1 1, 12) and arrays for liquid chromatography detectors (13). Geometries include those created by photoresist images (14, 'TO whom all correspondence should be addressed 15), carefully placed contiguous carbon fibers (13), sites of inactive oxides on metal substrates (16,17), metal mesh (l8), and platinum particles dispersed in polymer films (19,20). A variety o t new geometries which may be able to be prepared at the 100 A level has been reported (21).…”