Real-Time Observation of Reaction Processes of CO2 on Cu(997) by Ambient-Pressure X-ray Photoelectron Spectroscopy
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The reaction of CO2 on the vicinal Cu(997) surface at 340 K under CO2 gas pressure of 0.8 mbar was investigated by ambient pressure X-ray photoelectron spectroscopy. A main reaction product on the surface was identified as carbonate (CO3), based on estimation of the composition ratio of oxygen to carbon. CO3 was produced on the surface through the reaction of CO2 with oxygen formed from CO2 dissociation. The amount of adsorbed CO3 was increased and saturated as time elapsed. After saturation of adsorbed CO3, atomic oxygen appeared on the surface, indicating that CO2 dissociation into CO and O continued to take place. The present study shows the importance of CO3 intermediate in the CO2 chemistry on stepped Cu surfaces.
KeywordsCarbon dioxide Carbonate Copper Ambient pressure X-ray photoelectron spectroscopy
The present work was supported by the Advanced-Catalytic-Transformation program for Carbon utilization (ACT-C) of Japan Science and Technology Agency (JST). This work was carried out as joint research in the Synchrotron Radiation Research Organization and The Institute for Solid State Physics, The University of Tokyo (Proposal No. 2014B7479 and 2015A7491). Y.S. acknowledges financial support from The University of Tokyo, Research Assistantship Program. K.T. acknowledges financial support from the Ministry of Education, Culture, Sports, Science and Technology of Japan (Photon and Quantum Basic Research Coordinated Development Program). R.L. acknowledges financial support from The University of Tokyo Fellowship, Special Scholarship Program for International Students. The authors would like to thank J. Nakamura and Y. Morikawa for many helpful suggestions and discussions. The authors are grateful for the valuable advice and discussion in the design phase of our AP-XPS system: H. Bluhm, D. E. Starr, M. Salmeron, Z. Liu, E. Crumlin, S. Axnanda, S. Kaya, H. Ogasawara, A. Nilsson, F. Tao, S. R. Zhang, F. Rochet, J.-J. Gallet, G. Olivieri, M. G. Silly, F. Sirroti, and H. Kondoh. We would also like to thank J. Wittich, C. Amicabile, T. König at SPECS Surface Nano Analysis GmbH and K. Matsuda at Tec Corporation for the installation of the system.
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