Studies of the chemical preparation of mixed ZrO2, ZnO and CuO thin films on Si substrates with the potential application as catalysts for the synthesis of MeOH from CO2 and H2

Abstract

In these times where the energy consumption is increasing without stopping and, consequently, pollution and green house gases aggravate global warming, the focus is on developing new strategies to obtain non-hazardous energies. One of them is the formation of methanol from syngas. The objective of this project was to form metal oxide films on silicon substrates with future perspective of creating a remodelled catalyst for the synthesis of methanol. The metal oxides investigated were ZrO2, ZnO and CuO. Different methods, such as chemical vapour deposition, spin-coating and drop casting, were studied for that purpose. However, it was only the last method tested which accomplished part of the goal. The experiments were performed with different reactants, solvents and temperatures. The deposited species were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM-EDS). The results of the solution of Cu/Zn with oxalic acid and ammonia seem to indicate that it is possible to form an amorphous film with these compounds. For further studies, it would be interesting to use other reactants since the solutions tested in the present experiments were not stable enough for the attempted procedures. In particular, no really good solution for zirconyl chloride, ZrOCl2, was obtained. A possible way to improve the results would be the preparation of microemulsions and while some experiments with ZrOCl2 appeared promising, the time did not allow a more thorough exploration of the idea. A further problem was the sometimes poor affinity between the metal containing solution and the substrate.