Heterojunction Mediated Interfacial Selenium Vacancy Facilitating Spontaneous N═O Bonds Breakage Toward Efficient Ammonia Electrosynthesis

Abstract The electrocatalytic nitrates reduction reaction driven by green electricity provides a feasible pathway for simultaneously achieving the elimination of nitrates pollutants and production of valuable ammonia. However, the electrocatalytic efficiency is limited by the low ammonia yield rate and Faradaic efficiency. Vacancy engineering is an efficient strategy for improving the performance of catalysts. Here, we develop an efficient strategy of heterojunction (Ni 3 Se 4 /CoSe 2 ) mediated interfacial selenium vacancy toward efficient ammonia electrosynthesis. In situ characterizations combined with theoretical calculations reveal that the interfacial selenium vacancy on CoSe 2 segment strengthens the adsorption of nitrates, spontaneously breaks the N═O bonds of nitrates, thereby accelerating the overall NO 3 RR. The Ni 3 Se 4 /CoSe 2 heterojunction nanosheets array achieves an ammonia yield of 1.44 mmol cm −2 h −1 and Faradaic efficiency of 94.8% at a current density of 350 mA cm −2 . Furthermore, the Ni 3 Se 4 /CoSe 2 heterojunction electrode was assembled into a zinc–nitrate battery as the cathode, delivering an open‐circuit voltage of 1.46 V, a maximum power density of 12.71 mW cm −2 , and a charge–discharge stability of over 168 h.