In order to mimic the selective and reversible two-electron two-protonation reduction of CO2 based on the [NiFe] CO-dehydrogenase enzyme, various electrochemical approaches have been developed to optimize the existing electrocatalysts. A series of transition metal carbonyl bipyridyl complexes based on group VII elements (e.g. manganese/rhenium) have been developed and proven to be highly selective for the reduction of CO2 to CO. However, group VI elements have received less attention. Experimentally, it has been proven that M[(bpy-R)(CO)4] (M = Mo, W) species can reduce CO2 to CO with high Faradaic efficiencies at relatively negative potentials. In this work, electronic structure calculations have been performed in order to study the reaction mechanism for CO2-to-CO conversion using M[(bpy-R)(CO)4] species in the presence of proton sources such as trifluoroethanol. In contrast to electrocatalysts based on rhenium and manganese, a 2-CO2 configuration has been observed and proven to be thermodynamically more favorable than the usual 1-CO2 adduct. Furthermore, in order to characterize the transition states and activation energy barriers during the protonation steps, the proton source (e.g. 2TFEH) has been explicitly computed and an optimized conjugate acid/base couple was used as the reference to discuss the protonation steps.

Mechanistic study for the electrocatalytic CO2 reduction by M[(bpy-R)(CO)4] (M = Mo, W) complexes

2019 Spring National Meeting

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