FeNC catalysts for CO2 electroreduction to CO: effect of nanostructured carbon supports

CO2 electroreduction to CO is an attractive strategy for using CO2 as a feedstock for the production of organic chemicals. However, there is still a need to develop catalysts based on non-noble metals since the best catalytic systems for that specific reaction are based on silver and gold, in particular when high current densities are required. Iron- and nitrogen-doped carbon materials (FeNC) have recently emerged as cheap, stable and active alternatives, however with still limited current densities. Here we report that both the current density and the selectivity of FeNC-based cathodes can be significantly improved by mixing FeNC with carbon materials such as carbon nanotubes (CNT) or carbon nanofibers (CNF). More specifically, we show that a cathode based on a FeNC-CNF composite material shows ca. a twice higher j(CO)/j(H2) ratio and up to twice higher j(CO) value over a broad potential range. The FeNC-CNF electrode compares well with Ag and Au electrodes with a very high selectivity for CO production (FY for CO of almost 90%) and current densities above 10 mA cm(-2) at -0.7 V vs. RHE.