One solution to improve catalytic efficiency while reducing precious metal usage is to build metal clusters from a “bottom-up” approach by assembling individual atoms one by one into multiatomic clusters. A stable organic semiconductor, polyaniline, as the isolation matrix is used to produce the atomic clusters, which can consists of few atoms of the same metal or atoms of different metals. Customizable atomic composition produces certain distinct chemical properties, which have followed theoretically predicted catalytic properties. Production of these catalysts requires significantly less precious metal (by a factor of one to ten thousand) while maintaining comparable catalytic efficiency. This has been demonstrated by electrooxidations of propanol as well as other aliphatic alcohols by not only atomic gold consisting of 2-7 metal atoms but also atomic alloys of palladium and gold in different atomic ratios.
- Efficient — Atomic level catalyst dispersion to maximize available catalytic sites
- Controllable — Atomic control of cluster formation to generate pure metal and alloy catalysts of specific size and is scalable
- Economical — Minimal precious catalytic metal needed
- Fuel cells (vehicle market, stationary and portable power, off-road applications, marine vessels, consumer electronics, direct fuel cells, etc.)
- Gas sensors (lower explosive limit, carbon monoxide, breathalyzer, oxygen, etc.).
Properties, preparation, and practical applications of metal catalysts depend on their size. When it is on the order of tens of nanometers and larger, the clusters contain millions and millions of atoms. Such clusters consist of active surface atoms while the rest have properties characteristic of organized but inactive bulk phase. Their preparation is typically done in the “top-down” manner, essentially starting from a large object and using the size as the controlling parameter during the various scaling-down processes. The resulting devices contain substantial percentage of non-active metal catalyst.