Ultrafine Fe_2C Iron Carbide Nanoclusters Trapped in Topological Carbon Defects for Efficient Electroreduction of Carbon Dioxide

摘要

Normally, the CO_2 reduction reaction (CO_2RR) on Fe-based materials isunfavorable due to the poisoning of reaction sites by CO products. By modulatingthe electronic structures of Fe sites via carbonization, the CO bindingstrength can be optimized to facilitate the CO_2RR. In the present study, a dualN-elimination strategy is adopted to synthesize and stabilize a rarely reportediron carbide phase Fe_2C nanoclusters with a mean diameter of 1.07 nmtrapped in topological carbon defects. Notably, the ultrafine Fe_2C clusterspresent an excellent performance on electrocatalytic CO_2RR, which can drivea current density of 8.53 mA cm~(?2) with Faradaic efficiency of 97.1% for COproduction at ?0.7 V versus reversible hydrogen electrode. Density functionaltheory calculations reveal that the nanometric Fe_2C cluster possesses muchweaker binding with CO than the Fe crystalline surfaces and other iron carbides,thus promoting the CO desorption and overall CO_2RR process.