The Coupling of Rh‐Ru Dual Sites with Interfacial Oxygen Endows MoSe2 with Efficient Ammonia Electrosynthesis

The electrochemical nitritereduction reaction (NO2RR) to ammonia (NH3) is an intricate multielectron coupled proton transfer process, involving the adsorption and deoxygenation of NO2− to form intermediates (*NO), followed by the protonation of *NO to generate NH3. Tandem catalysis is a promising approach for enhancing the NO2RR and suppressing side effects; however, it is still challenged by the lack of well‐designed catalysts to drive this catalytic process. Herein, a catalyst is introduced, featuring Rh−Ru atomic‐pair dual sites that couple with interfacial oxygen‐containing species confined within a MoSe2 lattice (RhRu‐MoSe2‐xOy), enabling the unprecedented selective conversion of NO2− to NH3 under a low potential. Systematic experimental and computational studies reveal that the construction of Rh‐Ru sites married with adjacent oxygen‐containing groups can achieve the synchronous dispatch of water activation and hydrogenation of NO2. Moreover, the nitrite reduction on RhRu‐MoSe2‐xOy preferably proceeds via the NHO* pathway (NO*→NHO*), effectively circumventing the high energy barrier associated with the O‐side pathway (NO*→NOH*). Consequently, such a tandem system holds superior performance for robust NH3 electrosynthesis at a relatively low potential, achieving a high NH3 Faradaic efficiency of 93.0% at −0.2 V (vs RHE) and an exceptional NH3 production rate of 9.2725 mmol h−1 mgcat−1 at –0.4 V. Furthermore, the resulting catalysts attain ultra‐low overpotentials in a membrane electrode assembly (MEA) electrolyzer, featuring cell voltages of 2.1 V at current densities of 400 mA cm−2 and stable operation under industrial conditions for 200 min.