Surface science studies of model fuel cell electrocatalysts

Underpotential deposition at single crystal surfaces of Au, Pt, Ag and other materials

Shape- and size-controlled supported metal and intermetallic nanocrystallites are of increasing interest because of their catalytic and electrocatalytic properties. In particular, intermetallics PtX (X 5 Bi, Pb, Pd, Ru) are very attractive because of their high activity as fuel-cell anode catalysts for formic acid or methanol oxidation. These are normally synthesized using high-temperature techniques, but rigorous size control is very challenging. Even low-temperature techniques typically produce nanoparticles with dimensions much greater than the optimum <6 nm required for fuel cell catalysis. Here, we present a simple and robust, chemically controlled process for synthesizing size-controlled noble metal or bimetallic nanocrystallites embedded within the porous structure of ordered mesoporous carbon (OMC). By using surface-modified ordered mesoporous carbon to trap the metal precursors, nanocrystallites are formed with monodisperse sizes as low as 1.5 nm, which can be tuned up to ∼3.5 nm. To the best of our knowledge, 3-nm ordered mesoporous carbon-supported PtBi nanoparticles exhibit the highest mass activity for formic acid oxidation reported to date, and over double that of Pt–Au.

Nanocrystalline intermetallics on mesoporous carbon for direct formic acid fuel cell anodes

Electrochemical behaviour of palladium electrode: Oxidation, electrodissolution and ionic adsorption

Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for the investigation of electrocatalytic formic acid oxidation. The binary particles exhibited much less self-poisoning and a lower activation energy relative to Pt nanocubes, consistent with the single crystal study.

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M.J. Llorca

Papers

Formic acid oxidation on Pdad + Pt(100) and Pdad + Pt(111) electrodes

Electrochemical structure-sensitive behaviour of irreversibly adsorbed palladium on Pt(100), Pt(111) and Pt(110) in an acidic medium

Preliminary study of the electrochemical adsorption behaviour of a palladium modified Pt(111) electrode in the whole range of coverage

Formic acid oxidation on Pt(111) electrodes modified by irreversibly adsorbed selenium

Oxidation of formic acid on Pt(100) electrodes modified by irreversibly adsorbed tellurium