Artificial photosynthesis capable of the CO₂ reduction reaction (CO₂RR), with solar energy as external excitation energy and water (H₂O) as the electron and proton source, has been considered an attractive method to achieve a sustainable energy cycle, since it allows direct solar-to-chemical energy conversion. To design such systems, X-ray techniques play an important role for gaining the fundamental understanding needed to tailor its components and assemblies, by providing their chemical and structural information [1-3]. We have utilized surface-sensitive soft and hard X-ray techniques to investigate the interaction of metal catalytic surfaces with electrolytes and/or gases (H₂O and/or CO₂) under in situ/operando conditions. Among those, Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS) probes CO₂ adsorption on catalyst surfaces, providing the information of the initial atomic level events for CO₂ electroreduction on the metal catalysts. In situ X-ray absorption spectroscopy, on the other hand, can complement the study by providing metal catalytic surface sensitive information. We discuss in situ studies of the CO₂ reduction reaction, with Cu and related oxides and alloys.

Reference

[1] Lee, S.H.; Lin, J.C.; Farmand, M.; Landers, A.T.; Feaster, J.T.; Avilés Acosta, J.E.; Beeman, J.W.; Ye, Y.; Yano, J.; Mehta, A.; Davis, R.C.; Jaramillo, T.F.; Hahn, C.; Drisdell, W.S., J. Am. Chem. Soc. 143, 588–592 (2020).

[2] Ye, Y.; Su, J.; Lee, K.-J.; Larson, D.; Valero-Vidal, C.; Blum, M.; Yano, J.; Crumlin, E.J., J. Phys. D: Appl. Phys. 54, 234002 (2021).

[3] Ye, Y.; Qian, J.; Yang, H.; Su, H.; Lee, K. -J.; Etxebarria, A.; Cheng, T.; Xiao, H.; Yano, J.; Goddard, W. A.; Crumlin, E. J., ACS Appl. Mater. Interfaces, 12, 25374–25382 (2020).