Electrochemical synthesis of ammonia directly from N₂ and water over iron-based catalysts supported on activated carbon

Abstract

A CO2-free electrosynthesis of ammonia from air and water is presented with a solid Fe2O3 catalyst confined to activated charcoal.

Ammonia Synthesis from Electrocatalytic N2 Reduction under Ambient Conditions by Fe2O3 Nanorods

“…(1)] and reacts with N 2 and water [Eq. ] …”

Electrochemical Synthesis of Ammonia from Water and Nitrogen: A Lithium‐Mediated Approach Using Lithium‐Ion Conducting Glass Ceramics

“…True sustainability, however, will only be realized if the electrons required for the N 2 reduction originate from water rather than H 2 . Over the last three decades, such electrochemical processes have been developed, with state‐of‐the art technologies summarized in Table S1 in the Supporting Information . Unfortunately, the faradaic efficiencies (FEs) in most cases were unbearably low (<5 %) as the competing hydrogen evolution from water or a proton was preferred over the intended N 2 reduction, which was particularly sluggish owing to the strong triple bond of N 2 (941 kJ mol −1 ) .…”

“…[5] True sustainability,h owever,w ill only be realized if the electrons required for the N 2 reduction originate from water rather than H 2 .Over the last three decades, such electrochemical processes have been developed, with state-of-the art technologiess ummarized in Ta ble S1 in the Supporting Information. [6][7][8][9][10][11][12][13][14][15][16] Unfortunately,t he faradaic efficiencies (FEs) in most cases were unbearably low (< 5%)a st he competing hydrogen evolution from water or ap rotonw as preferred over the intended N 2 reduction, which was particularly sluggish owing to the strong triple bond of N 2 (941 kJ mol À1 ). [3,17,18] Innovative strategies are thus indispensable to overcome such obstacles and achieve excellent selectivity in the N 2 reduction.One promisingw ay is to employ Li as amediator in the electro-synthesis.…”

Chemical Transformation of Fe, Air & Water to Ammonia: Variation of Reaction Rate with Temperature, Pressure, Alkalinity and Iron

“…Both water saturated, CO2-scrubbed air or 99.999% N2 yielded similar efficiencies of ammonia generation. 1,7,8 Metallic iron was determined as the chemical intermediate, 96 and the ammonia production electrocatalyst (iron oxide) can be stand-alone, 1,7 or isolated on activated carbon. 8 Here, we explore the solar-free electrochemical-free chemical component of the ammonia synthesis, reaction 1B.…”

“…1,7,8 Metallic iron was determined as the chemical intermediate, 96 and the ammonia production electrocatalyst (iron oxide) can be stand-alone, 1,7 or isolated on activated carbon. 8 Here, we explore the solar-free electrochemical-free chemical component of the ammonia synthesis, reaction 1B. That is the rate of ammonia production by the chemical reaction of iron, N2 (from air or as pure nitrogen) and water is studied as a function of (1) iron particle size, (2) iron concentration, (3) temperature, (4) pressure and (5) concentration of the alkaline reaction medium that consists of an aqueous solution of equal molal concentrations of NaOH and KOH (Na0,5K0,5OH).…”