Metal cooperativity for visible-light driven CO2 reduction with new photosensitizers and catalysts (CO2-COP)

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The catalytic reduction of carbon dioxide (CO2) represents a highly active and challenging research field. Especially the photocatalytic recycling of CO2 and its utilization as a carbon feedstock could show severe impact on the global carbon balance as it allows to lower greenhouse gas emissions analog to natural photosynthesis pathways. Towards that end, chemistry plays a key role in developing such technologies by addressing the fundamental scientific challenges. Herein, pre-eminent catalyst development is of paramount importance and both homogenous and heterogeneous approaches are widely pursued. Due to the numerous spectroscopic techniques available and ease of synthetic alterations, studies on molecular transition metal complexes are vital for obtaining mechanistic insight on structurally very well-defined systems and are thus highly attractive to develop fundamental strategies for selective CO2 reduction processes. This approach requires the know-how of synthetic coordination chemists, photochemists, electrochemists and spectroscopists and will herein be attempted by joint efforts of the Wenger, Apfel and Robert groups. Inspired by Nature that enables selective activation of CO2 utilizing enzymatic bi-metallic active sites with a facilitated and selective multi-electron/multi-proton reduction through metal cooperativity, synthetic bi-metallic complexes will be rationally developed employing only earth-abundant metals. Furthermore, by tuning and controlling the metal cooperativity by targeted design of ligand backbone structures, we will aim at a selective synthesis of methanol, methane or short-chain hydrocarbons from CO2 in visible-light driven processes. To enable a light-driven CO2 reduction, these novel catalytic systems, however, likewise require novel suitable and potent photosensitizers. Thus, photosensitizers made from earth abundant transition metals will be synthesized and investigated for their photophysical properties. Consequently, the photosensitizers and catalysts will be synchronized in an iterative process between all groups. These findings will have far-reaching implications for photochemistry in general, as well as for CO2 reduction and activation in particular.