Chemical functionalization of porous carbon based materials to enable novel modes for efficient electrochemical N2 fixation The central motivation of the thesis was to provide possible solutions and concepts to improve the performance (e.g. activity and selectivity) of electrochemical N2 reduction reaction (NRR). Given that porous carbon based materials usually exhibit a broad range of structural properties they could be promising NRR catalysts. Therefore the advanced design of novel porous carbon based materials and the investigation of their application in electrocatalytic NRR including the particular reaction mechanisms are the most crucial points to be addressed. In this regard three main topics were investigated. All of them are related to the functionalization of porous carbon for electrochemical NRR or other electrocatalytic reactions. In chapter 3 a novel C TixOy C nanocomposite has been described that has been obtained via simple pyrolysis of MIL 125(Ti). A novel mode for N2 activation is achieved by doping carbon atoms from nearby porous carbon into the anion lattice of TixOy. By comparing the NRR performance of M Ts and by carrying out DFT calculations it is found that the existence of (O )Ti C bonds in C doped TixOy can largely improve the ability to activate and reduce N2 as compared to unoccupied OVs in TiO2. [...]