Achieving High Activity and Selectivity of Nitrogen Reduction via Fe–N₃ Coordination on Iron Single-Atom Electrocatalysts at Ambient Conditions

Abstract

Electrocatalytic nitrogen reduction reaction (NRR) represents a highly promising process to ammonia synthesis for artificial N2 fixation. However, the yield rate for NH3 production and Faradaic efficiency (FE) are still low, which greatly hinder its widespread applications. Until now, although a variety of catalysts, including single-atom catalysts, have been developed for NRR in the pursuit of suppressing hydrogen evolution reaction (HER) and the corresponding higher FE, the limited NH3 yield rate makes them uncompetitive for the synthesis of ammonia. Herein, we report a Fe single-atom catalyst anchoring on a nitrogen-doped carbon substrate (Fe SAC/N–C) as a highly efficient NRR catalyst. The catalyst achieves a high FE of 39.6% in 0.1 M KOH under room temperature, particularly a dramatically enhanced NH3 yield rate of 53.12 μgNH3 h–1 mgcat –1. The isotopic labeling (15N2) experiment confirms that the NH3 production completely originates from N2 reduction. Meanwhile, theoretical calculations and X-ray fine structure analysis reveal that the Fe–N3 coordination of Fe SAC/N–C is indeed responsible for the suppression of HER, particularly resulting in a maximum activation of NRR intermediates to produce ammonia with a high yield rate.

Establishing the Principal Descriptor for Electrochemical Urea Production via the Dispersed Dual‐Metals Anchored on the N‐Decorated Graphene

“…Following the experimental preparation of tricoordinated single‐metal MN 3 (M = Fe, Ru, Ni) and dispersed dual‐metals CuN 3 –CuN 4 configurations, [ 19 , 20 , 21 ] and complementary merits of the tricoordinated MN 3 with sufficient strong interaction with N 2 molecule and the long‐distance dual‐metals with superior tendency to form side‐on N 2 configuration, [ 7 , 10 , 11 , 22 ] the structural models comprising 6 × 6 graphene unit cells with homonuclear MN 3 –MN 3 moiety and heteronuclear MN 3 –M'N 3 moiety are constructed, namely M 2 @N 6 G and MM’@N 6 G. In this work, 27 kinds of transition metals (without the radioactive Tc and toxic Hg) in the periodic table of elements are taken into consideration ( Figure 1 a ), generating 27 groups of M 2 @N 6 G and 351 (27×26÷2) groups of MM’@N 6 G systems.…”

“…[ 22a ] Encouragingly, the single atom catalysts (SACs) RuN 3 and FeN 3 moieties anchored on graphene have been prepared and confirmed to be the superior electrocatalyst for N 2 reduction to NH 3 with the Faradaic efficiency of 29.6% and 39.6%, respectively. [ 20 ] Therefore, combining complementary merits of the tricoordinated MN 3 and the long‐distance dual‐metals, hereby the atomically dispersed dual‐metals (homonuclear MN 3 –MN 3 moiety and heteronuclear MN 3 –M'N 3 moiety) constructed on N‐decorated graphene (M 2 @N 6 G and MM’@N 6 G in short), are investigated as the latent electrocatalysts on urea production.…”

Single-Atom Photocatalysts for Emerging Reactions

“…Up until now, the majority of reports in the area of single-atom photocatalysts are focused on several well-known reactions, e.g., H 2 production, 62 − 68 N 2 fixation, 69 − 74 and CO 2 conversion. 32 , 34 , 47 , 50 , 59 , 75 In contrast, there are fewer works on the application of single-atom photocatalysts for emerging reactions to generate the value-added chemicals and/or energy sources, such as H 2 O 2 , 38 phenol, 76 imines, 77 syngas (CO and H 2 ), 78 HDN, 42 and β-ketosulfones.…”

Recent advances in material design and reactor engineering for electrocatalytic ambient nitrogen fixation

“…Single-atom catalysts composed of isolated metal atoms fixed on a support have become promising heterogeneous catalysts, 185–188 where they have achieved remarkable performances in various electrocatalytic reactions. 189–191 However, research on the electrocatalytic N 2 reduction and NH 3 formation reactivity of SACs is still limited. Tian and coworkers studied a molybdenum graphene-based electrocatalyst for electrochemical N 2 fixation.…”