Platinum Monolayer on Nonnoble Metal—Noble Metal Core—Shell Nanoparticle Electrocatalysts for O₂ Reduction.

Abstract

Catalysts H 2000Platinum Monolayer on Nonnoble Metal-Noble Metal Core-Shell Nanoparticle Electrocatalysts for O2 Reduction. -New O2 electrocatalysts with a high activity and very low noble metal content consisting of Pt monolayers deposited on the surfaces of carbon-supported non-noble-noble metal core-shell nanoparticles such as Pt/Au/Ni, Pt/Pd/Co, and Pt/Pt/Co are synthesized. The core-shell nanoparticles are formed by impregnation of Vulcan X-72C carbon with mixed solutions of noble and non-noble metal salts such as AuCl3, NiCl2, K2PtCl4, CoCl2, and PdCl2. A Pt monolayer is deposited by galvanic displacement of a Cu monolayer deposited at underpotentials. The mass activity of all three Pt monolayer electrocatalysts is more than an order of magnitude higher than that of a commercial Pt-C electrocatalyst. Because the new catalysts contain only a fractional amount of Pt and a very small amount of another noble metal, the cost of fuel cells could be lowered considerably. -(ZHANG, J.; LIMA, F. H. B.; SHAO, M. H.; SASAKI, K.; WANG, J. X.; HANSON, J.; ADZIC*, R. R.; J.

Toyota MIRAI Fuel Cell Vehicle and Progress Toward a Future Hydrogen Society

“…Higher specific activity (SA) and lower electrochemical surface area (ECSA) or higher Pt utilization in the catalyst with roughly equal ECSA and SA compared to existing catalysts are being explored, for example, using Pt nano-frame and core-shell catalysts, respectively. 8,9 Modeling and simulation are expected to improve the associated issues. [10][11][12] At the same time, non-noble metal catalysts, oxide catalysts, and carbon alloys are being actively researched.…”

Platinum Monolayer Electrocatalysts for the Oxygen Reduction Reaction: Improvements Induced by Surface and Subsurface Modifications of Cores

“…On the top of the "volcano" plot is the Pt monolayer on a Pd(111) surface, that is, the most active electrocatalyst among six Pt monolayer-substrate couples, plus the single Pt(111) surface. Our experiments on various Pt monolayer nanoparticles also demonstrated that the variation of the core materials significantly affect the performance of the catalyst [1,[3][4][5][6][7][8][9][10]. Among the Pt ML electrocatalysts we studied for the ORR, the palladium and palladium alloy cores outperform the rest in terms of both activity and stability [6,19].…”

“…We summarize the corresponding mass activity and specific activity for the ORR in the inset of Figure 5; 0.25-fold and 0.5-fold enhancements were found, respectively. 3 Co/C. The oxygen-reduction reaction on Pt ML /Pd 3 Co/C attained a Pt mass activity 2∼3-fold that of commercial Pt/C [7].…”

“…The above examples of surface modifications of Pd and Pd 3 Co core demonstrated that the removal of surface lowcoordination sites via bromide-treatment enables to obtain nanoparticles with smooth surfaces having a high density of (111)-oriented facets and a slightly contracted structure. The after-treated cores become excellent substrate for Pt monolayer and significant enhancements were realized of the mass activity and specific activity for the ORR.…”

“…Since the first development, Pt ML electrocatalysts with various core materials were designed and synthesized for assorted reactions in fuel-cell applications [1,[3][4][5][6][7][8][9][10]. Many of them exhibit excellent activities and stabilities.…”