In situ growth of nanostructured copper and zinc mixed oxides on brass supports as efficient microreactors for the catalytic CO oxidation

This work analyzed the in situ growth of nanostructured films of copper and zinc mixed oxides on brass substrates by a simple vapor oxidation route and their use as microreactors for the catalytic oxidation of CO. Thin and well-anchored films of nano-oxides were obtained, while the evolution over time of the physicochemical characteristics during growth was studied by XRD, SEM, EDS, LRS and XPS. At short treatment times a total coverage of the substrate with nano-oxide growths was obtained in a sequence in which first a base layer of zinc oxide was produced over which, subsequently, an increasing surface proportion of copper oxides progressively evolved. This stratification is a unique characteristic that contrasts with that of films obtained by conventional thermal treatments in air in which an outer layer of zinc oxide is produced. In this way, the study shed light on the understanding of the in situ growth mechanism of nano-oxides on brass substrates. Furthermore, this system showed a good performance for the catalytic CO oxidation reaction at relatively low temperatures, combining several attributes such as activity, reaction stability, low-cost materials and a simple and mild synthetic methodology. The non-noble metal-based microreactor with highly stabilized nano-oxide structures onto brass became an efficient and low-cost alternative for the catalytic CO oxidation reaction.