The project aims to generate a fundamental understanding of electrochemical processes that will enable the conversion of excess electrical energy produced by renewable sources to chemical energy, and store it in the form of fuels or useful chemical feedstocks. This can be realized by conversions of greenhouse gas molecules within the carbon- or nitrogen-cycle. The mechanisms of the reduction of such gases, as for example CO2 and NOx, are overall very complex and not well understood. The bottleneck in both cases is that our state-of-the-art understanding of the C-C or N-N bond-making reactions is not sufficiently developed. The reason for this lack of fundamental understanding is that the vast majority of research in the field has not been carried out on well-characterized surfaces, making the interpretation of experimental data very difficult. In this project, model surfaces will be utilized following a surface science approach, to obtain the necessary insights and breakthroughs related to the important C-C or N-N bond-making steps. This understanding is essential before considering any potential applications. This approach has been pioneered by the outgoing host group for fuel cell reactions and has established them as world-leaders in the field of electrocatalysis. This eminently successful approach will be used in this project as a basis for understanding the reactions of greenhouse gases. The strength of this project lies on the wide range of ex-situ and in-situ characterization methods that will be employed, in which the outgoing host has world-class expertise and facilities which are the best of the state of the art at an international level. The applicant will receive world-class training which will be a massive boost for his European career development. Moreover, the return host is determined to absorb the unique knowledge that will be gained. The applicant and the return host aim to a long-term collaboration after the completion of this fellowship.