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Journal Article

Ultrafast Real-Time Dynamics of CO Oxidation over an Oxide Photocatalyst

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Rubio,  A.
Center for Free-Electron Laser Science;
Nano-Bio Spectroscopy Group, Departamento de Fisica de Materiales, Universidad del País Vasco, UPV/EHU;
Theory Group, Theory Department, Max Planck Institute for the Structure and Dynamics of Matter, Max Planck Society;
Center for Computational Quantum Physics, Flatiron Institute;

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Citation

Wagstaffe, M., Wenthaus, L., Dominguez-Castro, A., Chung, S., Lana Semione, G. D., Palutke, S., et al. (2020). Ultrafast Real-Time Dynamics of CO Oxidation over an Oxide Photocatalyst. ACS Catalysis, 10(22), 13650-13658. doi:10.1021/acscatal.0c04098.


Cite as: http://hdl.handle.net/21.11116/0000-0007-5EA1-A
Abstract
Femtosecond X-ray laser pulses synchronized with an optical laser were employed to investigate the reaction dynamics of the photooxidation of CO on the anatase TiO2(101) surface in real time. Our time-resolved soft X-ray photoemission spectroscopy results provide evidence of ultrafast timescales and, coupled with theoretical calculations, clarify the mechanism of oxygen activation that is crucial to unraveling the underlying processes for a range of photocatalytic reactions relevant to air purification and self-cleaning surfaces. The reaction takes place between 1.2 and 2.8 (±0.2) ps after irradiation with an ultrashort laser pulse leading to the formation of CO2, prior to which no intermediate species were observed on a picosecond time scale. Our theoretical calculations predict that the presence of intragap unoccupied O2 levels leads to the formation of a charge-transfer complex. This allows the reaction to be initiated following laser illumination at a photon energy of 1.6 eV (770 nm), taking place via a proposed mechanism involving the direct transfer of electrons from TiO2 to physisorbed O2.