Concave-convex surface oxide layers over copper nanowires boost electrochemical nitrate-to-ammonia conversion

The room-temperature nitrate electroreduction to ammonia recycles the fixed nitrogen and offers an appealing ammonia-synthesis scenario. Electrocatalyst engineering is of vital importance to accelerate the reaction kinetics and increase the product selectivity during nitrate electroreduction to ammonia. In this work, Cu nanowires with concave-convex surface Cu2+1O layers (Cu@Cu2+1O NWs) were fabricated by a facile surface engineering strategy. Interior metallic Cu components allow for efficient electronic transmission capability along the nanowire structure, while exterior concave-convex Cu2+1O layers endow abundant catalytically active sites. Furthermore, the electronic interaction and interface effect between Cu/Cu2+1O enable tuning of the Cu d-band center and modulating the adsorption energies of intermediates. Consequently, the electroreduction ability of nitrate-to-ammonia over the Cu@Cu2+1O NWs is substantially improved, evident by the high nitrate-N conversion rate (78.57%), ammonia yield rate (576.53 mu g h(-1) mg(cat)(-1)) and ammonia Faradaic efficiency (87.07%) at the optimal applied potential (-1.2 V vs. saturated calomel electrode) for 2 h. The findings in the study are worth reference to tailor surface/interface properties and atom structure towards highly efficient electrocatalysts.