Rendering Photoreactivity to Ceria: The Role of Defects

Chengwu Yang; Xiaojuan Yu; Philipp N Pleßow; Stefan Heißler; Peter G Weidler; Alexei Nefedov; Felix Studt; Yuemin Wang; Christof Wöll

doi:10.1002/anie.201707965

Rendering Photoreactivity to Ceria: The Role of Defects

Angew Chem Int Ed Engl. 2017 Nov 6;56(45):14301-14305. doi: 10.1002/anie.201707965. Epub 2017 Oct 4.

Authors

Chengwu Yang¹, Xiaojuan Yu¹, Philipp N Pleßow², Stefan Heißler¹, Peter G Weidler¹, Alexei Nefedov¹, Felix Studt², Yuemin Wang¹, Christof Wöll¹

Affiliations

¹ Institute of Functional Interfaces, IFG, Karlsruhe Institute of Technology, KIT, 76344, Eggenstein-Leopoldshafen, Germany.
² Institute of Catalysis Research and Technology, IKFT, Karlsruhe Institute of Technology, KIT, 76344, Eggenstein-Leopoldshafen, Germany.

PMID: 28859239
DOI: 10.1002/anie.201707965

Abstract

The photoreactivity of ceria, a photochemically inert oxide with a large band gap, can be increased to competitive values by introducing defects. This previously unexplained phenomenon has been investigated by monitoring the UV-induced decomposition of N₂ O on well-defined single crystals of ceria by using infrared reflection-absorption spectroscopy (IRRAS). The IRRAS data, in conjunction with theory, provide direct evidence that reducing the ceria(110) surface yields high photoreactivity. No such effects are seen on the (111) surface. The low-temperature photodecomposition of N₂ O occurs at surface O vacancies on the (110) surface, where the electron-rich cerium cations with a significantly lowered coordination number cause a local lowering of the huge band gap (ca. 6 eV). The quantum efficiency of strongly reduced ceria(110) surfaces in the photodecomposition of N₂ O amounts to 0.03 %, and is thus comparable to that reported for the photooxidation of CO on rutile TiO₂ (110).

Keywords: CeO2; IRRAS; photocatalysis; surface chemistry; vibrational spectroscopy.

Publication types

Research Support, Non-U.S. Gov't