CVD synthesis of cobalt spinel for bio-butanol combustion

•Co3O4 thin films were tailored synthesized with a new feedstock of Co(acac)3/toluene by PSE-CVD.•The films were characterized with respect to structure, morphology, composition and redox properties.•Co3O4 show higher growth rate, more lattice oxygen and better re-oxidation property than those from Co(acac)2/ethanol.•The catalytic test showed that Co3O4 was active and only CO2 was the final product.•The surface basic sites and the redox properties are proposed to play a significant role in the performance of the catalyst.

As potential substitutes for precious metals, cobalt spinel has been considered as a promising alternative catalyst for the low-temperature catalytic oxidation of biofuels. This work reports the one-step synthesis of cobalt spinel by a more elaborated approach named pulsed-spray evaporation chemical vapor deposition with a new feedstock of Co(acac)3 and toluene. The obtained samples were comprehensively characterized in terms of structure and morphology (XRD, FTIR, Raman and SEM), chemical composition (XPS and EDS) and the redox properties (TPR/TPO). The structural and morphological analysis indicates that the synthesized thin films are pure cubic Co3O4 with homogeneous matrix with well-defined facets and straight edges. Compared to the commonly used feedstock of Co(acac)2/ethanol, Co(acac)3/toluene could result in a much higher growth rate, more lattice oxygen on the surface and better re-oxidation property. The Co3O4 film exhibits attractive performance towards the deep oxidation of n-butanol by preventing the formation of CO and acetaldehyde. The relationship between the peculiar structure and properties of Co3O4 is highlighted. The surface basic sites, specific morphology and the redox properties are proposed to play synergistic roles in the reaction sequence.

Graphical abstractPSE-CVD was used as effective tailored synthesis route for the Co3O4 thin films deposition with a new feedstock of Co(acac)3/toluene. Systematic and comprehensive characterizations were performed to obtain the structural, morphological, composition and ionic states as well as the redox properties. The effectiveness of Co3O4 to reduce high emission of by-products in biofuels combustion has been revealed. The surface basic sites and the redox properties were proposed to play key roles in the performance of the catalyst.Download high-res image (221KB)Download full-size image