The ZnxZr1−xO2−y solid solution on m-ZrO2: Creating O vacancies and improving the m-ZrO2 redox properties

Abstract In order to improve the redox properties of m -ZrO 2 , three different amounts of Zn were added to this oxide using a simple and effective technique. The XRD, XPS and Raman techniques showed that Zn did not form a ZnO phase but instead it diffused inside the first layers of m -ZrO 2 lattice. The XRD, EPR and also TPD of H 2 O results indicated the formation of oxygen vacancies when Zn was added to m -ZrO 2 . These results showed that Zn replaces Zr in the m -ZrO 2 lattice forming a surface solid solution (Zn x Zr 1−x O 2−y ). The TPR-H 2 experiments exhibited that as the Zn concentration increased, the H 2 consumption raised as well. The TPD of ethanol depicted that Zn catalysts were able to oxidize ethanol whereas m -ZrO 2 was not. These results are associated with the higher oxygen mobility and reducibility of these samples compared with m -ZrO 2 . Finally, it was verified that increasing the Zn concentration in the catalysts, increases the CO 2 conversion rate in the RWGS reaction, as well. Thus, the formation of the Zn x Zr 1−x O 2−y surface solid solution generates O vacancies and improves the reducibility and O mobility of m -ZrO 2 . Adding Zn to m -ZrO 2 changes the redox properties of the oxide