Iron-Oxide Nanoarrays Covered Carbon Fiber Promotes Ammonia Electrosynthesis and Multi-Scenario Applications

The development of electrocatalysts with complex environmental adaptability is the key path to promote the directional conversion of nitrate into high value-added ammonia. Herein, low-cost self-supporting carbon fiber was used as a carrier to successfully prepare uniform-sized Fe₂O₃ nanoarrays with four-corner double cone morphology (named Fe₂O₃/CF) through a one-step in situ growth method. Fe₂O₃/CF exhibits excellent performance in the electrocatalytic reduction of nitrate to ammonia: it maintains stable activity in a wide pH range and exhibits significant resistance to common interfering ions in complex water; The Faradaic efficiency of ammonia generation can reach 95%, and it has good long-term stability. The open-circuit voltage of 1.37 V and the power density of 12.3 mW cm^-2 can be achieved in the Zn-NO₃ ^- battery system based on Fe₂O₃/CF. Ammonia synthesis with low carbon emission and continuous production of liquid nitrogen fertilizer are realized by using solar power generation module. Combined with non-thermal plasma air activation technology, the green stepwise conversion of "air-nitrogen oxides-ammonia" can also be efficiently completed. Experiments and theoretical demonstrate that the Fe₂O₃ nanoarray uniformly dispersed on the surface of carbon fibers enables efficient and highly selective reduction of nitrate to ammonia by exposing specific crystal planes and providing high-density active sites.