Dual-Interface Synergistically Accelerating Tandem Catalysis in Ammonia Synthesis and Direct Ammonia Fuel Cell Application

Tandem electrochemical nitrate reduction reaction (NO3RR) as a promising approach for environment-friendly ammonia (NH3) synthesis is proposed due to the mismatched kinetic processes between NO3– ion adsorption and the subsequent hydrogenation of nitrogen-containing intermediates. In this contribution, the self-supported dual-interface Fe2O3/CoO@NC nanoarray catalysts are designed and synthesized as tandem electrocatalysts for NO3RR. Benefiting from the dual-interface synergistic effect, the multisite tandem CoO@NC interface with the pyridine N is conducive to the ″H2O molecule H–OH bond cleavage″ and further increases the hydrogenation reduction of nitrogen-containing intermediates. Furthermore, introduction of a Fe2O3/CoO heterogeneous interface promotes electron transfer from the Co to Fe sites, which thus enhances the ″NO3– adsorption/activation″ on the Co site. Moreover, Fe2O3 can be used as the matrix to connect Ni foam (NF) with CoO@NC, thus improving electron utilization and conductivity. These advantages endow the Fe2O3/CoO@NC nanoarrays with an ultrahigh NH3 yield rate of 166.13 mg h–1 cm–2, a superior Faradaic efficiency of 97.65%, an outstanding effective current density of 2095.30 mA cm–2, and an excellent operation durability during the 45th cyclic experiment (45 h). Notably, the NH3/H2O2 direct ammonia fuel cell (DAFC) equipped with an Fe2O3/CoO@NC anode reaches a remarkable peak power density of 13.58 mW cm–2 at room temperature.