The electrocatalytic reduction of CO2 into hydrocarbon fuels, like methane or ethylene, is regarded as one of the best methods to address one of the main current environmental issues: reducing the CO2 footprint of our society. However, in order to meet the demands of the energy transition (i.e. reduce the CO2 footprint with 80-95% by 2050), longer hydrocarbon chains with three or more carbon atoms (C>2) have to formed out of CO2. Our research focuses on the synthesis of colloidal metal nanoparticles with various sizes and shapes (e.g. nanorods or nanoplatelets) in order to design the ultimate electrocatalyst, and use these nanoparticles in the CO2 reduction reaction (CO2RR) for the production of C>2 hydrocarbons. Our main interest lies in unravelling where the reaction takes place by performing in-situ diffraction and spectroscopy measurements, ideally under true reaction conditions. Colloidal nanomaterials are ideally suited for this purpose, since they can be prepared with atomic precision in solution, which not only allows us to deposit them on various electrodes, but also characterize the size, shape and faceting during the reaction. This will give valuable fundamental, but also practical insights into the exact reaction mechanism of CO2RR and the (de)activation of the electrocatalyst nanoparticles, which will allow us to rationally design the ultimate electrocatalyst. Furthermore, the size-, shape- and composition-tunability of colloidal nanomaterials can be used to direct and induce C-C coupling, in order to efficiently produce C>2 hydrocarbons from CO­2.