Energy conversion catalysis using semiconducting transition metal cluster compounds

Abstract

Semiconductors containing transition metal clusters within their crystal lattice have recently been proposed as catalysts for multi-electron transfer reactions. This is because of the expected action of the clusters as reservoirs for electronic charge carriers and sites for cooperative electron transfer at a reasonably constant electrochemical potential^1,2. Here we report the first test of the capacity of such materials for oxygen reduction in an acid medium, for operation in fuel cells. The compound Mo_4.2Ru_1.8Se₈, which contains octahedra statistically composed of 4.2 molybdenum and 1.8 ruthenium atoms, turned out to have a catalytic behaviour comparable to platinum, which has so far been the best catalyst for fuel cells. The material costs of this new type of catalyst amount to only a few per cent of those of platinum.