Fuel cells are expected to become one of major sources of clean energy in the not too distant the future. Despite definitive advances in recent years, existing fuel-cell technology still has several drawbacks. The inadequate efficiency of energy conversion, the high Pt content of electrocatalysts, and low durability are some of them. These problems must be resolved before broad-scale application of fuel cells can take place.

Platinum monolayers on metal oxides are candidate electrocatalysts for improving the oxygen reduction reaction due to the plausible effects of the oxide's OH or O and vacancy sites on the OH coverage on Pt and an enhanced splitting of the O-O bond, respectively. Furthermore, increased stability of the Pt deposits may result from adsorption of Pt cations on oxide surfaces. Beside the above features, an appropriate metal oxide support must be stable under the oxidizing conditions of oxygen reduction and preferably conductive.

The objective of the work is to obtain basic information on the deposition of Pt monolayer-level deposits on oxide surface. The RuO₂(110) surface will be a model system because of its rare suitability for atomic scale surface chemistry, its conductivity and stability under the oxidizing conditions of oxygen cathode. Electrochemical experiments showed that Pt deposition involves large crystallization overpotential. A deposition of a 1/8 ML of Pt, with Pt atoms arranged in quasi-hexagonal array, is followed by Pt island growth. Experimental results are compared with predictions of density functional theory calculations.