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In situ Observation of Porosity Formation in Porous Single-crystalline TiO2 Monolith for Enhanced and Stable Catalytic CO Oxidation |
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| Authors: | Fangyuan Cheng Jie Zhang Prof. Kui Xie |
| Affiliation: | 1. Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002 China Advanced Energy Science and Technology Guangdong Laboratory, 29 Sanxin North Road, Huizhou, Guangdong, 116023 China University of Chinese Academy of Sciences, Beijing, 100049 China;2. Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350002 China |
| Abstract: | Introducing pores in single crystals creates a new type of porous materials that incorporate porosity and structural coherence. Herein, we use in situ transmission electron microscopy to disclose the porosity formation by converting KTiOPO4 (KTP) single crystals into porous single-crystalline (PSC) TiO2 monoliths in a solid-solid transformation. The isolated crystalline nuclei of TiO2 clusters with identical lattice orientation on KTP surface moves TiO2/KTP interface toward mother phase for growing PSC TiO2 monoliths. The relative density in PSC TiO2 monoliths dominates porosity while the macroscopic dimensions remain unchanged in the transformation. The single-crystalline nature of porous architecture stabilizes oxygen vacancy to activate lattice oxygen while the three-dimensional percolation enhances species diffusion. PSC TiO2 monoliths with deposited Pt clusters show enhanced and stable catalytic CO oxidation in air at ∼75 °C for 200 hours of operation. |
| Keywords: | Porous single crystal TiO2 In situ TEM Solid-solid transformation CO oxidation |