Unravelling the Role of Structural Geometry and Chemical State of Well-Defined Oxygen Vacancies on Pristine CeO2 for H2O2 Activation

Zicong Tan; Jieru Zhang; Yu-Cheng Chen; Jyh-Pin Chou; Yung-Kang Peng

doi:10.1021/acs.jpclett.0c01557

Unravelling the Role of Structural Geometry and Chemical State of Well-Defined Oxygen Vacancies on Pristine CeO₂ for H₂O₂ Activation

J Phys Chem Lett. 2020 Jul 16;11(14):5390-5396. doi: 10.1021/acs.jpclett.0c01557. Epub 2020 Jun 24.

Authors

Zicong Tan¹, Jieru Zhang¹, Yu-Cheng Chen², Jyh-Pin Chou³, Yung-Kang Peng^{1

4}

Affiliations

¹ Department of Chemistry, City University of Hong Kong, Hong Kong SAR, China.
² Department of Mechanical Engineering, City University of Hong Kong, Hong Kong SAR, China.
³ Department of Physics, National Changhua University of Education, Changhua 500, Taiwan.
⁴ City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, China.

PMID: 32545965
DOI: 10.1021/acs.jpclett.0c01557

Abstract

Although H₂O₂ has been often employed as a green oxidant for many CeO₂-catalyzed reactions, the underlying principle of its activation by surface oxygen vacancy (V_o) is still elusive due to the irreversible removal of postgenerated V_o by water (or H₂O₂). The metastable V_o (ms-V_o) naturally preserved on pristine CeO₂ surfaces was adopted herein for an in-depth study of their interplay with H₂O₂. Their well-defined local structures and chemical states were found facet-dependent affecting both the adsorption and subsequent activation of H₂O₂. It is concluded that a strong adsorption of H₂O₂ on ms-V_o may not guarantee its subsequent activation. The ms-V_o can be only free for the next catalytic cycle when the electron density of surface Ce is high enough to reduce/break the O-O bond of adsorbed H₂O₂. This explains the 211.8 and 35.8 times enhancement in H₂O₂ reactivity when the CeO₂ surface is changed from (111) and (110) to (100).