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Revealing Charge Transfer at the Interface of Spinel Oxide and Ceria during CO Oxidation

Year: 2021

Journal: ACS Catal., Volume 11, FEB 5, page 1516–1527

Authors: Yoon, Sinmyung; Jo, Jinwoung; Jeon, Beomjoon; Lee, Jihyeon; Cho, Min Gee; Oh, Myoung Hwan; Jeong, Beomgyun; Shin, Tae Joo; Jeong, Hu Young; Park, Jeong Young; Hyeon, Taeghwan; An, Kwangjin

Organizations: Basic Science Research Program of the National Research Foundation of Korea (NRF) - Ministry of Science and ICT [2018R1A1A1A05079555]; Technology Development Program to Solve Climate Changes of the National Research Foundation of Korea (NRF) - Ministry of Science and ICT [2017M1A2A2087630]; Engineering Research Center of Excellence Program of the National Research Foundation of Korea (NRF) - Ministry of Science and ICT [2020R1A5A1019631]; Ministry of Trade, Industry Energy (MOTIE) [20012971, 20010853]; Institute for Basic Science in Korea [IBS-R006-D1]; MSICT; KBSI [C030140, C030110, C030440]

Keywords: nanoparticle; interface control; non-noble metal catalyst; charge transfer; in situ characterization

The interface created between an active metal and an oxide support is known to affect the catalytic performance because of the charge transfer process. However, oxide-oxide interfaces produced by supported spinel oxide catalysts have been less studied owing to their complex interface structures and synthetic challenges. Herein, a synthetic strategy for Co3O4, Mn3O4, and Fe3O4 nanocubes (NCs) with a controlled CeO2 layer enables investigation of the role of the interface in catalytic oxidation. Notably, CeO2-deposited Co3O4 NCs exhibited a 12-times higher CO oxidation rate than the pristine Co3O4 NCs. In situ characterization demonstrates that the deposited CeO2 prevents the reduction of Co3O4 by supplying oxygen. The maximized interface resulting from Co3O4 NCs with three facets covered by CeO2 layers was found to exhibit the highest CO oxidation rate even under O-2-deficient conditions, which resulted from the versatile variation in the oxidation state. This study provides a comprehensive understanding of the Mars-van Krevelen mechanism occurring on the nanoscale at the Co3O4-CeO2 interfaces. The same activity trend and hot electron flow are observed for H-2 oxidation reactions using catalytic nanodiodes, thereby demonstrating that the origin of the activity enhancement is charge transfer at the interface.