A research conducted by Naonari Sakamoto et al., in collaboration with Nagoya University, was published in the Journal of the American Chemical Society.
The reuse of CO₂ as a resource is a key challenge in addressing climate change. Among various approaches, electrochemical conversion of CO₂ into valuable chemicals using catalysts is particularly promising. However, a major limitation has been the lack of direct experimental evidence of what happens during the reaction, with many mechanisms relying primarily on theoretical predictions.
In this study, the researchers immobilized a molecular iridium catalyst on an electrode and employed operando spectroscopy—techniques that enable real-time observation during the reaction. By combining X-ray absorption spectroscopy and surface-enhanced Raman scattering, they successfully tracked the reaction pathway of CO₂ reduction to formic acid. As a result, three distinct catalytic intermediates were directly observed and their temporal evolution was clarified. This provided experimental validation of the reaction mechanism, which had previously been difficult to confirm. These findings pave the way for rational catalyst design based on experimentally verified mechanisms, potentially improving efficiency and accelerating the practical implementation of CO₂ utilization technologies.
Title: Mechanism of CO2 Electrolysis with Heterogenized Molecular Iridium Catalysts Deciphered Using Operando Spectroscopy
Authors: Sakamoto, N., Sekizawa, K., Sato, S., Jung, J., Wakabayashi, T., Kamada, K., Nonaka, T., Uyama, T., Morikawa, T., Saito, S.
Journal Name: Journal of the American Chemical Society
Published: December 24, 2025
https://doi.org/10.1021/jacs.5c19250