Metal and Metal Oxide-Supported Platinum Monolayer Electrocatalysts for Oxygen Reduction

Research is directed towards the synthesis and characterization of Pt monolayer electrocatalysts supported by metal, metal alloy, non-noble metal - noble metal core - shell and oxide nanoparticles, or single crystal extended surfaces. This new approach has the potential to yield electrocatalysts with the lowest Pt content and improved catalytic activity, which can reduce the cost of fuel cells. In a parallel effort we are developing new improved Pd alloy electrocatalysts that can replace Pt in fuel cell cathodes. The structural, electronic and catalytic properties of electrocatalysts for O₂ reduction, methanol, ethanol and CO oxidation reactions are studied by in situ and ex situ synchrotron radiation, surface science, infrared and electrochemical techniques. The synthesis of Pt monolayer electrocatalysts is based on the unique method that involves a Pt monolayer deposition by displacement of an adsorbed Cu monolayer. Understanding the phenomena which determine the catalytic properties, structure-activity correlations, catalysts’ stability, segregation, structure and ordering of atomic and molecular monolayers at electrochemical interfaces is sought by combining the above techniques and kinetic analyses of the O₂ reduction reaction with intensive density functional theory calculations.
 

Research Activities:

Electrocatalysis

1. Pt monolayer Electrocatalysts for O₂ reduction: atomic-level synthesis, Electronic properties of Pt monolayers on single crystals and nanoparticles, Pt-support interactions; Structure-activity correlations; Pd alloy electrocatalysts; In situ spectroscopic studies of the O₂ reduction intermediates; Kinetic analyses of the O₂ reduction reaction.

Pt monolayer cathode electrocatalysts
structure	activity	stability
	fuel cell test
The first Pt monolayer-level electrocatalyst. No change in performance during ca. 900 hours as anode under fuel cell operating conditions

2. Pt submonolayer on Ru (PtRu₂₀) Electrocatalysts: H₂, CO and reformate H₂ oxidation; Pt content is 1/10 of that in commercial catalysts, high CO tolerance; Oxidation of Methanol and Ethanol; Adsorbate-Surface Interactions.

Research Activities

Surface Electrochemistry: To obtain a true microscopic description of electrochemical interfaces, structural and electronic properties of atomic and molecular monolayers on single-crystal and nanoparticle substrates are investigated using in situ scanning tunneling microscopy, surface x-ray scattering and x-ray absorption spectroscopy.

Recent Publications

J. Zhang, K. Sasaki, E. Sutter, R. R. Adzic, Stabilization of Platinum Oxygen Reduction
Electrocatalysts Using Gold Clusters, Science, 315 (2007) 220.

M. Shao, P. Liu, J. Zhang, R.R. Adzic, Origin of Enhanced Activity in Palladium Alloy Electrocatalysts for Oxygen Reduction Reaction, J. Phys. Chem. B.; (Article); 2007; 111(24); 6772-6775.

M.H. Shao, T. Huang, P. Liu, J. Zhang, K. Sasaki, V.B. Vukmirovic, R. R. Adzic, Palladium Monolayer- and Palladium Alloy- Electrocatalysts for Oxygen Reduction, Langmuir (Electrochemistry special issue) 22 (2006) 10409.

F.H.B. Lima, J. Zhang, M. H. Shao, K. Sasaki, M. B. Vukmirovic, E. A. Ticianelli, R. R. Adzic, Catalytic Activity - d-band Center Correlation for the O2 Reduction Reaction on Pt in Alkaline Solutions, J. Phys. Chem. C, 111(2007) 404.

J. Zhang, M. B. Vukmirovic, Y. Xu, M. Mavrikakis, R. R. Adzic, Controlling the Catalytic Activity of Platinum Monolayer Electrocatalysts for Oxygen Reduction with Different Substrates, Angew. Chem.. Int. Ed. 117 (2005) 2170.
 

J. X. Wang,; N. M. Markovic,; R. R. Adzic, Simulation of O₂ reduction on Pt(111) in Acid Solutions: Intrinsic Kinetic Parameters and anion adsorption effects. J. Phys. Chem. B, 108 (2004) 4127.
 

Junliang Zhang, Miomir B. Vukmirovic, Kotaro Sasaki, Anand Udaykumar Nilekar, Manos Mavrikakis, and Radoslav R. Adzic, Mixed-Metal Pt Monolayer Electrocatalysts for Enhanced Oxygen Reduction Kinetics, J. Am. Chem. Soc., 127 (2005) 12480.
 

M.H. Shao, P. Liu, R.R. Adzic, Superoxide is the intermediate in the oxygen reduction reaction on platinum electrode. J. Am. Chem. Soc., 128 (2006) 7408.

J. Zhang, F.H.B. Lima, M. H. Shao, K. Sasaki, J.X. Wang, J. Hanson, R. R. Adzic, Platinum monolayer on non-noble metal - noble metal core-shell nanoparticles electrocatalysts for O₂ reduction, J. Phys. Chem. B, 109 (2005) 22701-22704.

M.H. Shao, K. Sasaki, R.R. Adzic, Pd-Fe nanoparticles as electrocatalysts for oxygen reduction. J. Am. Chem. Soc., 128 (2006) 3526.

Supported by the the Division of Chemical Sciences, Geosciences, and Biosciences of the Office of Basic Energy Sciences of the Office of Science under contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.

Last Modified: January 31, 2008

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

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