Anchoring High-Concentration Oxygen Vacancies at Interfaces of CeO2鈥搙/Cu toward Enhanced Activity for Preferential CO Oxidation

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• 作者：Shaoqing Chen ; Liping Li ; Wanbiao Hu ; Xinsong Huang ; Qi Li ; Yangsen Xu ; Ying Zuo ; Guangshe Li
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：October 21, 2015
• 年：2015
• 卷：7
• 期：41
• 页码：22999-23007
• 全文大小：595K
• ISSN：1944-8252

文摘

Catalysts are urgently needed to remove the residual CO in hydrogen feeds through selective oxidation for large-scale applications of hydrogen proton exchange membrane fuel cells. We herein propose a new methodology that anchors high concentration oxygen vacancies at interface by designing a CeO_2鈥?i>x/Cu hybrid catalyst with enhanced preferential CO oxidation activity. This hybrid catalyst, with more than 6.1% oxygen vacancies fixed at the favorable interfacial sites, displays nearly 100% CO conversion efficiency in H₂-rich streams over a broad temperature window from 120 to 210 掳C, strikingly 5-fold wider than that of conventional CeO₂/Cu (i.e., CeO₂ supported on Cu) catalyst. Moreover, the catalyst exhibits a highest cycling stability ever reported, showing no deterioration after five cycling tests, and a super long-time stability beyond 100 h in the simulated operation environment that involves CO₂ and H₂O. On the basis of an arsenal of characterization techniques, we clearly show that the anchored oxygen vacancies are generated as a consequence of electron donation from metal copper atoms to CeO₂ acceptor and the subsequent reverse spillover of oxygen induced by electron transfer in well controlled nanoheterojunction. The anchored oxygen vacancies play a bridging role in electron capture or transfer and drive molecule oxygen into active oxygen species to interact with the CO molecules adsorbed at interfaces, thus leading to an excellent preferential CO oxidation performance. This study opens a window to design a vast number of high-performance metal-oxide hybrid catalysts via the concept of anchoring oxygen vacancies at interfaces.