A vacancy engineered MnO2−x electrocatalyst promotes nitrate electroreduction to ammonia

Abstract

The NO₃⁻ reduction reaction (NO₃RR) has recently emerged as a potential approach for sustainable and efficient NH₃ production, whereas exploring high-performance NO₃RR electrocatalysts is highly desirable yet challenging. Herein, we attempted to construct O-vacancies (OVs) on MnO₂ nanosheets and the resulting OV-rich MnO_2−x showed a high NH₃ yield of 3.34 mg h⁻¹ cm⁻² (at −1.0 V vs. RHE) and an excellent FE of 92.4% (at −0.9 V vs. RHE), together with the outstanding stability. DFT calculations reveal that OVs on MnO₂ serve as catalytic centers to enhance NO₃⁻ adsorption and dissociation, reduce the energy barriers of hydrogenation steps and thus promote NO₃⁻-to-NH₃ conversion.