High-efficiency electrocatalytic nitrite-to-ammonia conversion on molybdenum doped cobalt oxide nanoarray at ambient conditions.

As a high-efficiency electrocatalyst for NH 3 production via NO 2 − reduction, Mo-doped Co 3 O 4 nanoarray exhibits an extremely high Faradaic efficiency of 96.9 % and a corresponding NH 3 yield of up to 651.5 μmol/h cm−2 at −0.5 V. [Display omitted] • Mo-doped Co 3 O 4 nanoarray on titanium mesh is synthesized as an effective catalyst for NO 2 −-to-NH 3 conversion. • Mo-Co 3 O 4 /TM exhibits a high NH 3 Faradaic efficiency of 96.9 % and a related yield of 651.5 μmol h−1 cm−2 with strong stability. • DFT calculations reveal the catalytic mechanism of NO 2 −RR on Mo-Co 3 O 4. • The fabricated Zn-NO 2 − battery achieves a peak power density of 3.6 mW cm−2 and a satisfactory NH 3 yield of 108.4 μmol h−1 cm−2. Electrochemical conversion of nitrite (NO 2 −) contaminant to green ammonia (NH 3) is a promising approach to achieve the nitrogen cycle. The slow kinetics of the complex multi-reaction process remains a serious issue, and there is still a need to design highly effective and selective catalysts. Herein, we report that molybdenum doped cobalt oxide nanoarray on titanium mesh (Mo-Co 3 O 4 /TM) acts as a catalyst to facilitate electroreduction of NO 2 − to NH 3. Such a catalyst delivers an extremely high Faradaic efficiency of 96.9 % and a corresponding NH 3 yield of 651.5 μmol h−1 cm−2 at −0.5 V with strong stability. Density functional theory calculations reveal that the introduction of Mo can induce the redistribution of electrons around Co atoms and further strengthen the adsorption of NO 2 −, which is the key to facilitating the catalytic performance. Furthermore, the assembled battery based on Mo-Co 3 O 4 /TM suggests its practical application value. [ABSTRACT FROM AUTHOR]