Electrochemical Synthesis of Ammonia from Water and Nitrogen in Ethylenediamine under Ambient Temperature and Pressure

Abstract

In this study, a novel electrolysis cell based on ethylenediamine (EDA) as a cathodic solvent was developed for NH 3 electro-synthesis. The NH 3 -generating cathode chamber was filled with 0.1 M LiCl/EDA and separated by a cation exchange membrane from the anodic compartment, which was filled with 0.05 M H 2 SO 4 aqueous solution. It appeared that EDA was cathodically stable, and thus electron-stealing medium destruction was substantially avoided. The faradaic efficiency for NH 3 synthesis was 17.2%, producing 7.73 × 10 −7 mol NH 3 for 1 h electrolysis at a cell voltage of 1.8 V with the charge consumption of 1.3 C.

Recent Advanced Materials for Electrochemical and Photoelectrochemical Synthesis of Ammonia from Dinitrogen: One Step Closer to a Sustainable Energy Future

“…Fe on stainless steel [203] SO 4 solution was chosen as the anodic electrolyte ( Figure 3b). [52] Compared with their previous work using 2-propanol as the electrolyte with an FE lower than 1%, [53] an enhanced FE of 17.2% was achieved due to a synergistic effect of the EDA electrolyte which was cathodically stable enough to prevent H 2 from stealing the protons though HER and the H 2 SO 4 electrolyte worked as an excellent proton supplier. Recent publications applying various reaction cells in electrochemical ammonia synthesis are summarized in Table 1.…”

“…This additional degree of freedom may give rise to further optimized reaction conditions by selecting proper combinations of electrolytes. For example, Kim et al established a bi‐electrolyte system in which LiCl/ethylenediamine (EDA) was chosen as the cathodic electrolyte and H 2 SO 4 solution was chosen as the anodic electrolyte (Figure b) . Compared with their previous work using 2‐propanol as the electrolyte with an FE lower than 1%, an enhanced FE of 17.2% was achieved due to a synergistic effect of the EDA electrolyte which was cathodically stable enough to prevent H 2 from stealing the protons though HER and the H 2 SO 4 electrolyte worked as an excellent proton supplier.…”

“…[74,75] Unfortunately, these conventional catalysts suffer from the low production rate and current efficiency due to the strong HER competition in electrochemical NRR. While the exploration of bulk electrocatalysts has been extended to other metals, e.g., Pd and Ni, [45,52] metal oxides and sulfides, e.g., SnO 2 , ZnS [76] and conducting polymers, e.g., polyaniline, [77] these early experimental studies still demonstrate limited activities, selectivities and stabilities, and often need to operate at high temperatures (90-750 °C) to achieve moderate NH 3 yields. As witnessed by the recent development of materials chemistry, renewed interest on judiciously developing efficient materials for NRR electrocatalysis has led to a plethora of research efforts.…”

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.…”