Three-Dimensional Nitrogen-Doped Graphene Aerogel-Supported MnO Nanoparticles as Efficient Electrocatalysts for CO2 Reduction to CO

Electrochemical CO2 reduction reaction (CO2RR) is a promising alternative to deal with CO2 and generate green energy. Carbon monoxide (CO) is one key desired product of the CO2RR. Herein, a Mn-based heterogeneous catalyst by depositing MnO nanoparticles on three-dimensional N-doped graphene aerogels (NGAs) is synthesized. The catalyst exhibits a negligible onset potential of −0.27 V (vs RHE). This onset potential is 12.5% lower than that of bulk Au electrodes. Moreover, the higher Faradaic efficiency for CO is 86% at a potential of −0.82 V (vs RHE) and better stability over at least 10 h. The excellent CO2RR performance can be attributed to the large specific area of the unique 3D crumpled porous NGA nanostructure, the synergistic effect of well-crystallized MnO active sites, and effective hydrogen evolution reaction suppression from nitrogen doping. The enhancement effect is also revealed by the density functional theory method. Our results highlight a promising new class of low-cost, abundant electrocatalysts for synthetic fuels from CO2.