High-pressure synthesis of CO and syngas from CO2 reduction using Ni−N-doped porous carbon electrocatalyst

Abstract Electrochemical conversion of CO2 to CO or syngas (CO/H2 mixture) is considered one of the most promising approaches to valorise waste-CO2. To develop the process on industrial scale, it would be necessary to use selective and inexpensive electrodes and to obtain high productivities with low energy consumption. In this frame, Ni−NC catalysts are considered among the most interesting ones because of their relatively low cost, high faradaic efficiency in CO ( F E C O ), and high stability. However, up to now, quite low productivities were obtained as a result of low current densities achieved in aqueous electrolytes. In this work, we have evaluated the performances of a Ni−NC electrocatalyst at relatively high carbon dioxide pressures (5–30 bar) in a wide range of cell potentials and current densities. It is found that proper selection of CO2 pressure and catalyst loading improves drastically the performance of the process, obtaining high F E C O (close to 100%), high current densities (>100 mA cm−2), and high productivities. Furthermore, it is shown that it is possible to obtain syngas with a target ratio of two between H2 and CO under various operating conditions. As an example, syngas was obtained with FE close to 100% and a productivity of ∼18 mol h−1 m−2 working at 30 bar with a current density close to 195 mA cm−2.