@MASTERSTHESIS{ 2006:2048479222,
 	title = {DESEMPENHO DE ELETRODOS Pt/C, Pt3Cr/C E PtCr/C PARA
 APLICAÇÕES EM CÁTODOS DE CÉLULAS A COMBUSTÍVEL DE
 METANOL DIRETO},
 	year = {2006},
 	url = "http://tedebc.ufma.br:8080/jspui/handle/tede/928",
 	abstract = "This work presents oxygem reduction reaction (ORR) studies on platinum (Pt/C)
 and platinum-chromium alloys containing 50% (PtCr/C) or 70% in chromium (Pt3Cr)
 dispersed on high surface area, in acid aqueous solutions with and without metanol,
 with cyclic voltammetry, chronoamperometry and rotating disk electrode techniques.
 Electrochemical measurements have been also performed in a direct methanol unit
 fuel cell. The electrocatalysts were characterized by energy dispersive X-ray (EDX)
 and X-ray diffraction (XRD) analyses. The ORR studies in absence of methanol in
 solution showed that chromium adittion does not change the reaction mechanism
 observed on the Pt/C and the electrocatalytic activity increases in the order PtCr/C
 < Pt/C < Pt3Cr/C. Such increase was attributed to a favourable interatomic distance
 for O2 dissociative adsorption. The alloys showed higher tolerance to methanol
 presence in solution than Pt, mainly the PtCr electrode due to smaller amount of
 active sites to methanol adsorption with respect to Pt. In solutions containing low
 concentration of methanol, the ORR mechanism was not affected by methanol
 presence. The polarization curves recorded with the unit cell showed that na
 increase in temperature results in an increase in the electrocatalitic activity of the
 anode, as well as na increase in methanol diffusion through the Nafion® membrane
 with consequent cathode depolarization. Furthermore, the system containing
 Pt3Cr/C as cathodic electrode material presented the best electrochemical
 performance, with power densities of ~ 55 mW cm-2, in contrast to ~ 40 mW cm-2 for
 the unit cell with Pt/C cathode and ~ 20 mW cm-2 with PtCr/C.",
 	publisher = {Universidade Federal do Maranhão},
 	scholl = {PROGRAMA DE PÓS-GRADUAÇÃO EM QUÍMICA/CCET},
 	note = {QUIMICA}
}