Atomically Mo-Doped SnO_2-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 SnO_2-x with enriched O-vacancies (Mo-SnO_2-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-SnO_2-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.