Modeling of gas bubble-induced mass transport in the electrochemical reduction of carbon dioxide on nanostructured electrodes

Modeling the electroreduction of carbon dioxide can be of crucial importance in the design and development of innovative catalysts and reactors in order to advance the industrialization of this technological approach. In this work, we present a novel model which combines bubble-induced mass transport with the spatial distribution of the species involved in the reactions along the diffusion layer on nanostructured electrodes. The validity of this model has been proved through a study on electrodes with two different morphologies. It has been revealed, from the modeling, that the poor performance of particle-based electrodes at high kinetics can be attributed to the large departure diameter of the gas bubbles and consequently to a severe mass transport limitation. On the other hand, the dendritic morphology can guarantee an effective mass diffusion, even for high CO2 consumption rates, thus leading to a high performance over a wide potential range. The relationship between local pH and the formation of C2 products can also be interpreted well, on the basis of reliable experimental data and the valid model. Such a unique model offers new insights into structure-dependent mass diffusion and its effect on catalysis performance.