There has been a recent surge of (metal)-nitrogen-doped carbon ((M)-N-C) catalysts in the electrochemical reduction of CO2. Despite the rapid progress in activity and selectivity, there are still many open questions about the parameters dictating their catalytic performance. Many studies investigated the effect of different heteroatoms and aimed to identify the active sites. A wild range of carbon structures such as nanofibers, nanotubes, nanospheres, etc., were studied in these works with varying morphologies. The possible influence of catalyst morphology, however, is scarcely taken into account. To fill this void, we systematically elucidated the effect of catalyst porosity on the CO2 electroreduction performance of nanoporous N-C catalysts. By using a sacrificial support method we synthesized catalysts with uniformly-sized meso/macropores, which only differed in the pore size. Both the activity and the selectivity was notably affected by the pore structure of the catalysts. I am going to point out the factors correlated to the morphological aspects, we identified to be decisive in controlling their catalytic performance. I will also highlight the importance of isotopic labeling studies in CO2 electroreduction. Such experiments are important in confirming the reduction products being originated from CO2, and also to furnish mechanistic insights into the reduction process. By using non-equilibrated solutions of the selectively labeled the initial carbon sources (i.e., 13CO2 and H13CO3-), bicarbonate anion was identified as the predominant source of the carbon monoxide reduction product.

CO2 conversion on N-doped carbon electrodes: Morphological and mechanistic insights

2019 Spring National Meeting

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