Roles of hydroxyl and oxygen vacancy of CeO2·xH2O in Pd-catalyzed ethanol electro-oxidation

In the field of noble metal-catalyzed alcohol electro-oxidation reaction (AOR), huge attention is paid on the composition, size, facet, and structure of the metals, while the support engineering should also be emphasized. CeO 2 has been widely used as an unique support in AOR, primarily due to its abundant oxygen vacancies (O v ). Herein, we report CeO 2 · x H 2 O nanoparticles with both massive hydroxyl groups (OH) and O v remarkably enhance the catalytic activity and stability of Pd toward ethanol oxidation reaction (EOR). The CO striping experiments and density functional theory (DFT) calculations suggest that OH and O v on CeO 2 · x H 2 O surface bring about a large downshift of Pd d-band center and a significant weakening of CO absorption on Pd. Moreover, OH and O v also play synergic roles in the removal of toxic intermediates. Consequently, the important roles of OH and O v of CeO 2 · x H 2 O are confirmed in Pd-catalyzed EOR. The facile CeO 2 · x H 2 O-enhanced strategy can contribute to the catalyst design for other energy conversion reactions.