Abstract Green production of NH 3 , especially the Li‐mediated electrochemical N 2 reduction reaction (NRR) in non‐aqueous solutions, is attracting research interest. Controversies regarding the NRR mechanism greatly impede its optimization and wide applications. To understand the electrocatalytic process, we treated Au coated carbon fibrous paper (Au/CP) as the model catalyst. In situ XRD confirmed the transformation of lithium intermediates during NRR. Au greatly improved electron transfer kinetics to catalyze metallic Li formation, and accordingly highly accelerated spontaneous NRR. The Faradaic efficiency of NRR on Au/CP reached 34.0 %, and NH 3 yield was as high as 50 μg h −1 cm −2 . Our research shows that the key step of Li‐mediated non‐aqueous NRR is electrocatalytic Li reduction and offers a novel electrocatalyst design method for Li reduction.