The search for metal alloy electrocatalysts which exhibit an enhancement in activity over the pure components has been the focus of considerable effort with respect to a number of important reactions.
Oxygen Reduction at the cathode of Polymer Electrolyte Membrane Fuel Cells (PEMFC) relies on carbon supported platinum based catalysts. These are both expensive (precious metal) and unstable (support). Hydrogen Oxidation at the anode of Polymer Electrolyte Membrane Fuel Cells (PEMFC) also relies on carbon supported platinum based catalysts which are also expensive, and not tolerant to poisoning (e.g. CO in reformate fuel). High throughput synthesis and screening of these catalysts for their activities, varying the metal alloy used, the particle size, and the support, is being used to find improved and cheaper solutions. Screening of the materials for electrocatalytic activity has been achieved by adapting a pseudo-parallel electrochemical screening technique previously applied to high area supported catalysts to measure the lower currents on thin films. This is combined with a new silicon micro-fabricated screening chip incorporating 100 individually addressable electrodes. In addition, experiments on single crystal electrodes allow a detailed understanding of how structure and surface composition influence catalytic activity. The methods have been extended to include a high throughput screening using DEMS of the product distribution in metal alloy electrocatalysts for nitrate reduction.
