Innovative CVD synthesis of Cu2O catalysts for CO oxidation

• Pure Cu2O films were deposited at 250 °C using a direct chemical vapor deposition method
• The effect of water addition in the liquid feedstock of Cu(acac)2 and ethanol on the physicochemical properties and catalytic performance was investigated
• The synthesized Cu2O leads the complete oxidation of CO at 175 °C for Cu2O prepared with 5 vol.% of water with good reusability and reproducibility
• The enhanced activity is discussed regarding the crystallite grain size, optical property, lattice/adsorbed oxygen and the embedded geometry geometry.

The present work reports on a one-step synthesis of thin Cu2O films deposited at 250 °C using pulsed-spray evaporation chemical vapor deposition (PSE-CVD). Of interest, water addition (0, 2.5 and 5 vol.%) in the liquid feedstock of Cu(acac)2 and ethanol was found to have a significant effect on the catalytic performance of these films towards CO oxidation. The obtained films were comprehensively characterized with X-ray diffraction (XRD), Helium ion microscopy (HIM), X-ray photoelectron spectroscopy (XPS) and Ultraviolet–visible (UV–vis) spectrometry. Both the surface composition and optical properties exhibited good correlation with the catalytic activity. The adopted empirical catalytic screening based on light-off curves measurement demonstrated that Cu2O prepared with 5 vol.% of water in the reactant feedstock exhibited the best performance with respect to complete oxidation of CO at 175 °C. This finding is reproducible and tentatively attributed to reduced crystallite grain size and more surface oxygen species generated when water was added in the feedstock. Accordingly, the innovative combination of water addition in the feedstock and the use of PSE-CVD technique is expected to assist further synthesis of new efficient thin films paving the way for catalytic applications.

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