Optimizing FeNC Materials as Electrocatalysts for the CO2 Reduction Reaction: Heat‐Treatment Temperature, Structure and Performance Correlations

The direct CO2 electrochemical reduction reaction (CO2RR) into carbon‐based chemicals has attracted tremendous attention as a sustainable process for CO2 utilization. The viability of the process, however, is contingent on finding efficient catalysts based on earth abundant elements. Carbon‐based solid catalyst materials doped with nitrogen and transition metals (M−N−C) have emerged as a cost‐efficient alternative for the direct electrochemical reduction of CO2 into CO. These materials contain different N functionalities and MNx moieties which could be involved in the catalytic process. With the aim of gaining insight into the role of these different active sites and how to control their concentration we have prepared 5 polyaniline derived FeNC catalysts by changing the temperature of the heat treatment (750–1050 °C). We observed that it is possible to tune the ratio of the different N functionalities by changing the pyrolysis temperature. Furthermore, this had a clear impact on the catalytic performance of this family of FeNC materials. In particular, a higher temperature correlated with a larger FeNx concentration resulting in a high selectivity toward the CO2RR. These results indicate that FeNx moieties play a predominant role in the catalytic process and that the incorporation of such sites to the carbon structure is enhanced by the heat‐treatment temperature. Hot or not?: The catalytic performance of polyaniline‐derived FeNC catalysts towards the CO2 reduction reaction can be modified by changing the temperature of the heat treatment during the material synthesis. The catalyst treated at the lowest temperature is the most active one due to its large electrochemical surface area. The selectivity towards the CO2RR, however, is enhanced with a higher synthesis temperature, which is attributed to large concentration of FeNx, highlighting the importance of such sites on the catalytic performance of MNC materials.