(742c) Epitaxial ALD of Co Catalysts
Cobalt catalysts were prepared on porous Al2O3 supports by atomic layer deposition (ALD) that used sequential reactions of cobaltocene (CoCp2) and H2 at 483 to 523 K. This preparation method avoided formation of an intermediate oxide, so the catalysts could be activated at lower temperatures. Two types of Co were observed on the Al2O3 surface using HRTEM: Co particles with diameters between 0.6 and 1.8 nm (75% were smaller than 1 nm), and Co crystalline planes that were as large as 35 nm. Cobalt catalysts prepared by ALD retained adsorbed ligands that appeared to be stable for at least eight months at room temperature. Catalytic activity of the Co catalysts suggest that the epitaxial growth of multi-atom thick Co planes on crystalline surfaces of Al2O3 have significantly higher turnover frequencies and productivity.