SearchPublisher and Institutes
You are here: Home :: Area NEM :: Chemistry :: Physical chemistry
M.H. Shao, K. Sasaki, P. Liu, R.R. Adzic
Pd3Fe and Pt Monolayer-Modified Pd3Fe Electrocatalysts for Oxygen Reduction
Keywords: Palladium Alloy, Platinum Monolayer, Oxygen Reduction Reaction, Electrocatalyst, DFT
In a search for electrocatalysts based on other metals with comparable attributes to very scarce and expensive Pt, we studied the kinetics of the oxygen reduction reaction (ORR) on carbon-supported Pd3Fe alloy nanoparticles in HClO4 and NaOH solutions. In acid solution, the electrocatalyst´s activity for the ORR is slightly higher than that of commercial Pt/C. The reaction kinetics involves predominantly a four-electron reduction with the first charge-transfer step being the rate-determining one. The synthesis of a Pd overlayer on the Pd3Fe alloy´s surface at elevated temperatures is due to strong segregation effects. The major cause of this electrocatalyst´s high activity appears to be the downshifting of the d-band center of Pd overlayer, resulting in a weaker interaction between the oxygen-containing species and the Pd surface. We demonstrated a further enhancement of the ORR kinetics with a Pt monolayer-covered Pd3Fe/C electrocatalyst. In HClO4 solution, the mass-specific activity of Pt/Pd3Fe/C was about five times higher than that of commercial Pt/C, surpassing the Pt/Pd/C. In situ XANES data indicate that this elevated ORR activity may be due to the decreased formation of PtOH, and weaker oxygen adsorption on Pt/Pd3Fe/C.
Zeitschrift für Physikalische Chemie, Oldenbourg Wissenschaftsverlag
Print ISSN: 0942-9352
Volume: 221, 09/2007
Pages: 1175 - 1190