Boosting ammonia production in electrocatalytic NOx reduction on a robust Fe/FeMoO4 catalyst

Abstract

Electrocatalytic reduction of nitrate $$({\rm{N}}{{\rm{O}}_3}^ - )$$ and nitride $$({\rm{N}}{{\rm{O}}_2}^ - )$$ to ammonia (NH3) is of wide interest as a promising alternative to the energy-intensive Haber-Bosch route for mitigating the vast energy consumption and the accompanied carbon dioxide emission, as well as benefiting for the relevant sewage treatment. However, exploring an efficient and low-cost catalyst with high atomic utilization that can effectively facilitate the slow multi-electron transfer process remains a grand challenge. Herein, we present an efficient hydrogenation of $${\rm{N}}{{\rm{O}}_3}^ - /{\rm{N}}{{\rm{O}}_2}^ - $$ species to NH3 in both alkaline and neutral environments over the Fe2(MoO4)3 derived hybrid electrocatalyst with the metallic Fe site on FeMoO4 (Fe/FeMoO4). The Mo ingredient can play a synergistically positive role in further promoting the NH3 production on Fe. As a result, Fe/FeMoO4 behaves well in the electrochemical NH3 generation from $${\rm{N}}{{\rm{O}}_2}^ - $$ with a maximum NH3 Faradaic efficiency (FE) of 96.53% and 87.68% in alkaline and neutral electrolyte, corresponding to the NH3 yield rate of 640.68 and 302.56 $${\rm{mg}} \cdot {{\rm{h}}^{ - 1}} \cdot {\rm{m}}{{\rm{g}}_{{\rm{cat}}.}}^{ - 1}$$ , respectively, which outperforms the Fe and Mo counterpart and other similar catalyst, showing the robust catalytic capacity of each active site.