Graphdiyne-Supported Single Iron Atom: A Promising Electrocatalyst for Carbon Dioxide Electroreduction into Methane and Ethanol

Electrochemical reduction of carbon dioxide (CO2ER) to high-energy-density multicarbon products is a quite promising technique for large-scale renewable energy storage, for which searching for stable, inexpensive, and efficient catalysts is a key scientific issue. In this work, the potential of an experimentally available single iron (Fe) atom supported on graphdiyne (Fe/GDY) as the CO2ER catalyst was explored by means of density functional theory (DFT) computations. Our results revealed that Fe/GDY exhibits high stability due to the strong hybridization between the Fe 3d orbitals and the C 2p orbitals of GDY. Interestingly, due to the small limiting potential of −0.43 V, the anchored Fe atom can effectively reduce CO2 to CH4 along the following pathway: CO2 → HCOO* → HCOOH* → HCO* → H2CO* → H3CO* → O* + CH4 → OH* → H2O, in which the hydrogenation of HCOOH* to HCO* is the potential-determining step. Furthermore, the unsaturated HCO* species on Fe/GDY can provide an active site for further coupling with CO to generate C2H5OH with a small activation energy for C–C coupling. Our theoretical results not only propose a new approach to CO2ER to C2 products on a single-site catalyst but also further widen the potential applications of GDY.