Role of Electronic Property of Pt and Pt Alloys on Electrocatalytic Reduction of Oxygen

Abstract

Electrocatalytic activity of PtNi alloy surfaces formed by sputtering was investigated toward oxygen reduction reaction (ORB) in perchloric acid solution. Hydrodynamic voltammograms with rotated electrodes were utilized to measure the activity. Maximum activity was observed at ca. 30% of Ni content by which a ten times larger kinetic current density than that of pure Pt was attained. X-ray photoelectron spectroscopy analysis of the surfaces after the reaction indicated that the active surfaces were completely covered by Pt. The effect of Pt interatomic distance at the surface or of surface roughening was excluded as the cause of high activity. We present a mechanism of the ORR based on d electron vacancy at the surface Pt due to Ni content a few monolayers below the surface. This type of catalyst will contribute in development of fuel cells for electric vehicles and other applications.

Oxygen Reduction Activity and Durability of Ordered and Disordered Pt3Co Alloy Nanoparticle Catalysts at Practical Temperatures of Polymer Electrolyte Fuel Cells

“…42 The influence of heat-treatment conditions (temperature and time) on the Pt 3 Co alloy phase are shown in Figs. S1 and S2 in the Supporting Information.…”

“…We consider that these small particles might actually be Pt-like, not surviving ordered-Pt 3 Co, because the j k value reached a value nearly identical to that for pure Pt after only 10,000 cycles. When contacted with hot 0.1 M HClO 4 solution in the initial stage of the corrosion for both Pt 3 Co, Co atoms present on the surface of alloy particles can easily dissolve into the solution, as shown in Fig. 7.…”

“…4,5,14 It has been reported that the electronic structure of the Pt skin layer formed on Pt-M alloys could change with the composition of the underlying alloy, reaching a maximum at the optimum alloy composition or alloying metal species M. 24,[30][31][32] Because the surface is not perfectly covered with uniform Pt skin layer, j k often decreases appreciably by dealloying of M during the operation of PEFCs or electrochemical measurements in acidic electrolyte solutions, particularly at higher temperatures. 14,33 Here, we focus on the influence of crystal structure (ordered and disordered structures) of Pt 3 Co alloy nanoparticles on the ORR activity and durability. Intending to apply carbon-supported Pt-Co alloy cathode catalysts to phosphoric acid fuel cells (PAFCs), the UTC group has developed carbon-supported Pt-Co alloy catalysts with the ordered structure, 22 which was found to be more stable at 205…”

Synthesis and Electrocatalytic Performance of Multi-Component Nanoporous PtRuCuW Alloy for Direct Methanol Fuel Cells

“…After alloying with Ru, Cu and W, the lattice parameter of Pt changes which would bring about ligand and strain effects. This will accelerate the scission of the O-O bond and the formation of the OHads, thus increasing the O2 reaction rate [50,51]. On the other hand, the hydrogenation rates of OHads intermediates enhanced and reduced the coverage of Pt surface because of alloy effect [52].…”

Eletrocatálise das reações de oxidação de hidrogênio e de redução de oxigênio

“…A redução de oxigênio procede quantitativamente através do mecanismo peróxido em um grande número de superfícies eletródicas, particularmente em meio alcalino. Nas últimas décadas, muitos esforços têm sido dedicados ao estudo do mecanismo da RRO em soluções aquosas ácidas e alcalinas sobre diferentes materiais de eletrodo [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] . Em eletrólitos áci-dos, platina e ligas de platina ainda são consideradas as melhores opções para a redução de oxigênio, tanto em termos dos mais baixos sobrepotenciais desejáveis para promover a reação, quanto da estabilidade requerida.…”