In situ FTIR study of CO2 reduction on inorganic analogues of carbon monoxide dehydrogenase†
The CO2-to-CO reduction by carbon monoxide dehydrogenase (CODH) with a [NiFe4S4] cluster is considered to be the oldest pathway of biological carbon fixation and therefore may have been involved in the origin of life. Although previous studies have investigated CO2 reduction by Fe and Ni sulfides to identify the prebiotic origin of the [NiFe4S4] cluster, the reaction mechanism remains largely elusive. Herein, we applied in situ electrochemical ATR-FTIR spectroscopy to probe the reaction intermediates of greigite (Fe3S4) and violarite (FeNi2S4). Intermediate species assignable to surface-bound CO2 and formyl groups were found to be stabilized in the presence of Ni, lending insight into its role in enhancing the multistep CO2 reduction process.