Anthropological global warming and climate change pose a major threat to the future of our society. As internationally agreed on at the UN Climate Change Conference in Paris in 2015, it is therefore of central importance to significantly reduce net carbon dioxide (CO2) emissions. In this respect, transformation of atmospheric CO2 back into feedstock chemicals using chemical catalysis has emerged as a promising approach towards a carbon-neutral economy. To advance CO2 conversion catalysis towards full-scale applications, it requires highly effective catalysts that allow for driving the reaction with minimal energy losses and precisely controllable product selectivity. Up to now our understanding of how to rationally tune catalytic selectivity and activity remains poor hampering any advancement of the technology. Studying the catalytic mechanism of CO2 conversion catalyzed by small molecular complexes has become a favorable strategy towards understanding fundamental principle of the catalysis. Molecular metal complexes exhibit a simple and defined chemical framework for the catalytic reaction that also allows for tailored fine tuning of the ligand sphere to modulate the catalysis. Thus, they exhibit an ideal system to study structure-activity relationships. Understanding these is a major prerequisite for rational improvement of any CO2 catalytic conversion systems towards application.
In this project, we develop innovative spectroscopic approaches that allow for in situ investigations of the mechanism of molecular CO2 reduction catalysis. Specifically, powerful Fourier-transform infrared spectroscopy in the attenuated reflection mode coupled to electrochemistry is employed to investigate the interfacial catalytic reactions of manganese and rhenium transition metal complexes at a molecular level. Upon developing tailored immobilization strategies, we selectively bind the catalysts onto conductive electrode surfaces that enable controlled triggering of redox and catalytic reactions by applying potentials. Our studies aim at providing a detailed picture of the catalytic mechanism of these complexes on surfaces deriving general guidelines for rational enhancement of activity and selectivity for CO2 reduction catalysis.
