Iron-Doped MoO3 Nanosheets for Boosting Nitrogen Fixation to Ammonia at Ambient Conditions

Abstract

Nitrogen can be electrochemically reduced to produce ammonia, which supplies an energy-saving and environmental-benign route at room temperature, but high-efficiency catalysts are sought to reduce the reaction barrier. Here, iron-doped alpha-MoO3 nanosheets are thus designed and proposed as potential catalysts for fixing N-2 to NH3. The alpha-MoO3 band structure is intentionally modulated by the iron doping, which narrows the band gap of alpha-MoO3 and turns the semiconductor into a metal-like catalyst. Oxygen vacancies, generated by substituting Mo6+ for Fe3+ anions, are beneficial for nitrogen adsorption at the active sites. In 0.1 M Na2SO4, the Fe-doped MoO3 catalyst reached a high faradaic efficiency of 13.3% and an excellent NH3 yield rate of 28.52 mu g h(-1) mg(cat)(-1) at -0.7 V versus reversible hydrogen electrode, superior to most of the other metal-based catalysts. Theoretical calculations confirmed that the N2 reduction reaction at the Fe-MoO3 surface followed the distal reaction path.