Unravelling catalytic activity trends in ceria surfaces toward the oxygen reduction and water oxidation reactions

Abstract

Improved catalysts are critical for more environmentally friendly, and long-term oxygen electrochemical reactions. Computational catalysis can provide atomic level information that is critical for optimizing the next generation of electrocatalysts. It has been demonstrated that by varying the exposed planes, the catalytic performance of metallic oxides can be tuned. Herein, we investigate the role of CeO₂ surface orientations (100), (110), (111), (221), and (331) in enhancing catalytic activity toward various oxygen electrochemical reactions ranging from 4- and 2-electron oxygen reduction reactions (ORR) to 4-, 2- and 1-electron water oxidation reactions (WOR) using density functional theory (DFT) calculations in conjunction with the computational hydrogen electrode. Our results indicate that the CeO₂(100) facet is the most promising for 4-electron ORR, with a theoretical limiting potential of 0.52 V. We also show that the presence of oxygen vacancies can enhance the 4-electron ORR activity of the CeO₂(110) and CeO₂(111) surfaces. Besides, CeO₂(100) is selective for the 4-electron WOR while CeO₂(110) and CeO₂(111) are selective for the 2-electron and 1-electron WOR, respectively. Oxygen vacancies shift all the above three facets towards the 4-electron WOR. This work sheds light on the role of different ceria facets in various oxygen electrochemical reactions which is critical for developing better catalysts.