Electrochemical reduction of N2 to NH3 is a promising method for artificial N2 fixation, but it requires efficient and robust electrocatalysts to boost the N2 reduction reaction (NRR). Herein, a combination of experimental measurements and theoretical calculations revealed that a hybrid material in which ZnO quantum dots (QDs) are supported on reduced graphene oxide (ZnO/RGO) is a highly active and stable catalyst for NRR under ambient conditions. Experimentally, ZnO/RGO was confirmed to favor N2 adsorption due to the largely exposed active sites of ultrafine ZnO QDs. DFT calculations disclosed that the electronic coupling of ZnO with RGO resulted in a considerably reduced activation‐energy barrier for stabilization of *N2H, which is the rate‐limiting step of the NRR. Consequently, ZnO/RGO delivered an NH3 yield of 17.7 μg h−1 mg−1 and a Faradaic efficiency of 6.4 % in 0.1 m Na2SO4 at −0.65 V (vs. RHE), which compare favorably to those of most of the reported NRR catalysts and thus demonstrate the feasibility of ZnO/RGO for electrocatalytic N2 fixation.

Electrochemical conversion of N 2 to NH 3 offers a clean and energy-saving solution for artificial NH 3 production, but requires cost-effective, steady and highly efficient catalysts to promote N 2 reduction reaction (NRR). Herein, CuO employed as a new non-noble-metal NRR catalyst was investigated both experimentally and theoretically. When supporting the CuO nanoparticles on reduced graphene oxide (RGO), it was demonstrated that the resulting CuO/RGO nanocomposite could effectively and robustly catalyze NRR under ambient conditions. At À 0.75 V versus reversible hydrogen electrode, the CuO/RGO exhibited a high NH 3 yield of 1.8 × 10 À 10 mol s À 1 cm À 2 and Faradaic efficiency of 3.9 %, along with the excellent selectivity and high stability. Density functional theory (DFT) calculations revealed that the "Suf-end" was the most effective mode for N 2 adsorption on catalytic Cu atoms. In NRR process, the alternating associative route was the preferable pathway with *N 2 ! *NNH being the rate-determining step.Ammonia (NH 3 ) is an essential nitrogen chemical for manufacturing fertilizers, dyes, medicaments, explosives, etc. [1] Besides, NH 3 is also deemed as the next-generation liquid fuel and highefficiency energy carrier owing to its high energy density (4.32 kWh L À 1 ) and hydrogen capacity (17.6 wt%). [2] However, at present, the artificial ammonia production depends primarily on the Haber-Bosch process that operates under high pressure (150~300 bar) and high temperature (300~550°C), [1] leading to the significant energy consumption and enormous CO 2 emission. This motivates us to develop an alternative approach for sustainable and economical NH 3 synthesis under ambient conditions.Electrochemical conversion of N 2 to NH 3 at ambient conditions offers a clean and energy-saving solution for largescale NH 3 production, but requires efficient and stable electrocatalysts to accelerate the N 2 reduction reaction (NRR) rate. [1] The noble metals such as Au, [3] Ag [4] and Ru [5] are currently recognized as excellent catalysts for NRR. Nevertheless, the scarcity and high cost of noble metals greatly hinder their large-scale applications. Recent advances demonstrate the earth-abundant transition-metal sulfides, [6,7] carbides, [8,9] nitrides [10] and oxides [11] are the cost-effective alternatives towards NRR. Of these transition-metal-based catalysts, the metal oxides have attracted the most attention due to their facile preparation, favorable catalytic activity and high stability. Sun and coworkers recently reported a series of metal oxides, including Fe 3 O 4 , [12] VO 2 , [13] Cr 2 O 3 , [14] TiO 2 , [15] Nb 2 O 5 , [16] MoO 3 [17] and β-FeOOH [18] which were found to exhibit comparable or superior NRR activities to most noble metals. Nonetheless, the potentially high NRR performance of metal oxides is greatly limited by their poor conductivity, which lowers the electron-transfer efficiency unfavourable for NRR kinetic process. The most efficient way to tackle this problem is anchoring the metal oxides onto rob...