Stabilizing Cu0-Cuδ+ sites via ohmic contact interface engineering for ampere-level nitrate electroreduction to ammonia

The synergistic Cu0-Cuδ+ sites are found as the active sites for NH3 synthesis through nitrate electroreduction reaction, but still face significant challenges in stabilizing the Cuδ+ due to its self-reduction. Here we propose an Ohmic contact interface engineering strategy by loading copper nano-islands on indium hydroxide nanocubes. Attributed to the lower work function of Cu than that of In(OH)3 with n-type semiconductor nature, the electrons in Cu can transfer unimpededly to In(OH)3 at the interface of Ohmic junction, triggering and stabilizing polarized Cu0-Cuδ+ active sites. Cu@In(OH)3 sustains both high NH3 yield rate (4.28 mmol h−1 mgcat.−1) and Faradaic efficiency (97.35%) at −0.6 V vs. RHE, while maintaining stability for at least 120 h under an Ampere-level of 800 mA cm−2. Such Ohmic contact interface engineering approach allows for simultaneously constructing and stabilizing the Cu0-Cuδ+ for the electrosynthesis of ammonia, as well as other value-added chemicals relying on above active sites. An Ohmic contact interface engineering strategy was proposed by loading copper nano islands on indium hydroxide nanocubes, which could trigger and stabilize the polarized Cu0 -Cuδ+ active sites. Such catalyst enabled effective ammonia electrosynthesis with nitrate under ambient conditions