Vibrational Spectroscopy at Electrified Interfaces: Electrochemical CO₂ Reduction Reaction

The solid-liquid interfacial reactions play a crucial role in controlling the performance and stability of electrocatalysts^1-4. In situ vibrational spectroscopy techniques such as Raman and surface-enhanced infrared absorption spectroscopy (SEIRAS) are the powerful tools for examining the surface-adsorbed intermediates on the solid-liquid interfaces. In this talk, we report on our use of in situ SEIRAS, Raman, and X-ray absorption spectroscopy to investigate the electrochemical CO₂ reduction mechanism over the Cu-based electrocatalysts. The Cu-based electrodes with different oxidation states result in the formation of various CO intermediates such as CO_atop and CO_bridge. The co-existence of CO_atop and CO_bridge corresponds to the selectivity of CO₂-to-C₂H₄ reaction. Also, the bimetallic electrocatalysts are developed for efficient CO₂-to-HCOOH and CO₂-to-CO conversion processes. We found that the surface-adsorbed COO species with different binding structures play crucial role in the reduction process. The electronic structures of Cu-based electrocatalysts are associated with the formation of surface-adsorbed intermediates and electrocatalytic properties. The formation of surface-adsorbed intermediates and reaction mechanism associated with CO₂-to-HCOOH and CO₂-to-CO reactions over the bimetallic electrocatalysts will be discussed in detail.<br/><br/>References<br/>[1] T. Cheng, H. Xiao, W. A. Goddard, <i>J. Am. Chem. Soc.</i>, 138, 13802 (2016).<br/>[2] T.-C. Chou, C.-C. Chang, H.-L. Yu, W.-Y. Yu, C.-L. Dong, J. Velasco-Vélez, C.-H. Chuang, L.-C. Chen, J.-F. Lee, J.-M. Chen, and H.-L. Wu, <i>J. Am. Chem. Soc.</i>, 142, 2857 (2020).<br/>[3] X. Mo, X. Gao, A. V. Gillado, H.-Y. Chen, Y. Chen, Z. Guo, H.-L. Wu, E. C. M. Tse, <i>ACS Nano</i>, 16 12202 (2022).<br/>[4] K. B. Ibrahim, T. A. Shifa, M. Bordin, E. Moretti, H.-L. Wu, A. Vomiero, <i>Small Methods</i>, 2300348 (2023).