Ecole Politechnique Fédérale de Lausanne
Correlating activity, selectivity and stability with the structure and composition of catalysts is crucial to advancing the knowledge in chemical transformations which are essential to move towards a more sustainable economy. Among these, the electrochemical CO2 reduction reaction (CO2RR) holds the promise to close the carbon cycle by storing renewable energies into chemical feedstocks, yet it suffers from the lack of efficient, selective and stable catalysts. Furthermore, fundamental catalytic studies should be complemented with investigations under commercially-relevant conditions to assure actual progress in the field.
In this talk, I will present our recent group efforts towards the synthesis via colloidal chemistry of atomically de- fined nanocrystals (NCs) and their use as CO2RR catalysts. First of all, I will focus on our studies of NC nucleation and growth. A fundamental understanding of the formation mechanisms is crucial to rationally approach the de-sign of new and more complex catalytic materials. I will then illustrate how NCs with precisely tunable shapes, sizes and interfaces between different domains can help to identify selectivity rules at the branching nodes which lead to C1 and C2+ reduction products. Finally, I will discuss the role of NCs as model systems to study degradation pathways using ex-situ and in-situ transmission electron microscopy. These insights are essential when moving towards an actual technological implementation. I will conclude by sharing our results which illustrate that the above-discussed catalysts are not only model systems but can be implemented in a gas-fed electrolyzer and sustain the same selectivity at technologically relevant conditions with currents up to 300 mA/cm2.