Ultrafine Fe2C Iron Carbide Nanoclusters Trapped in Topological Carbon Defects for Efficient Electroreduction of Carbon Dioxide

Abstract Normally, the CO 2 reduction reaction (CO 2 RR) on Fe‐based materials is unfavorable due to the poisoning of reaction sites by CO products. By modulating the electronic structures of Fe sites via carbonization, the CO binding strength can be optimized to facilitate the CO 2 RR. In the present study, a dual N‐elimination strategy is adopted to synthesize and stabilize a rarely reported iron carbide phase Fe 2 C nanoclusters with a mean diameter of 1.07 nm trapped in topological carbon defects. Notably, the ultrafine Fe 2 C clusters present an excellent performance on electrocatalytic CO 2 RR, which can drive a current density of 8.53 mA cm −2 with Faradaic efficiency of 97.1% for CO production at −0.7 V versus reversible hydrogen electrode. Density functional theory calculations reveal that the nanometric Fe 2 C cluster possesses much weaker binding with CO than the Fe crystalline surfaces and other iron carbides, thus promoting the CO desorption and overall CO 2 RR process.