Atomically Mo-Doped SnO2-x for efficient nitrate electroreduction to ammonia

Electrochemical NO3--to-NH3 reduction (NO3RR) emerges as an appealing strategy to alleviate contaminated NO3- and generate valuable NH3 simultaneously. However, substantial research efforts are still needed to advance the development of efficient NO3RR catalysts. Herein, atomically Mo-doped SnO2-x with enriched O-vacancies (Mo-SnO2-x) is reported as a high-efficiency NO3RR catalyst, delivering the highest NH3-Faradaic efficiency of 95.5% with a corresponding NH3 yield rate of 5.3 mg h-1 cm-2 at -0.7 V (RHE). Experimental and theoretical investigations reveal that d-p coupled Mo-Sn pairs constructed on Mo-SnO2-x can synergistically enhance the electron transfer efficiency, activate the NO3- and reduce the protonation barrier of rate-determining step (*NO→*NOH), thereby drastically boosting the NO3RR kinetics and energetics.