Thin cobalt oxide films for catalysis deposited by plasma-enhanced metal-organic chemical vapor deposition

摘要

The plasma-enhanced metal-organic chemical vapor deposition was used to prepare thin films of cobalt oxide starting with cyclopentadienyldicarbonyl-cobalt(I) (CpCo(CO)_2) mixed with argon and oxygen. The films were characterized by Raman and Fourier transform infrared spectroscopies, electron diffraction, and energy dispersive X-ray microanalysis. Their thickness was estimated by ellipsometric measurements. Catalytic properties of the films were tested in oxidation of n-hexane. It has been found that spinel-type Co_3O_4 nanoclusters with a crystallite size of 4-6 nm are formed in the deposits. Amorphous carbon and amorphous CoO_x phases are also observed in the films. The content of these phases depends on the molar fraction of oxygen in the gas mixture. Preliminary catalytic tests have shown that precalcined Cr-Al steel carrier covered by the plasma-deposited films reveals much higher catalytic effect then the non-deposited substrate.