Issue 21, 2025

Tuning surface curvature in B and N co-doped CNT-derived Fe, Ru and Ir catalysts for electrochemical hydrogenation of N2 to NH3

Abstract

Single-atom catalysts (SACs) have tremendous applications in enhancing the catalytic performance in the electrocatalytic nitrogen reduction reaction (NRR). Carbon-based substrates have superior properties that improve the catalytic performance either by forming defects or by doping heteroatoms, such as B,N-doped graphene, S-doped graphene, and defective carbon nanotubes. However, the carbon nanotube (CNT)-based electrocatalysts for NRR study are currently less explored. Here, we use the FeB2N2-(n,0) CNTs (n = 3–8) as representative electrocatalysts to study the different CNT curvatures and reveal their effects on the N[triple bond, length as m-dash]N triple bond activation and adsorption free energy (ΔG) of the *N2 molecule, with changes in the potential-determining step in NRR. Zigzag B2N2-(6,0) CNTs were selected as the efficient substrate, with three transition metal atoms (TM = Fe, Ru and Ir) anchored on the B2N2-(6,0) CNT to construct the NRR catalysts. Using first-principles calculation and the computational hydrogen electrode (CHE) model, we investigated their electrocatalytic performance in NRR. FeB2N2-(6,0) CNT is the most efficient catalyst and has a low limiting potential (UL) of −0.551 V for NRR. Further, the projected partial density of states and projected crystal orbital Hamilton population analyses illustrate that the N2 activation is due to strong π*-backbonding, which leads to effective charge transfer between the active site (metal d-orbital) and N2 molecule (p-orbital). The FeB2N2-(6,0) CNT also showed high NRR selectivity, inhibiting the competitive hydrogen evolution reaction. Our study provides a detailed mechanism of catalysis by the carbon-based, high-efficiency electrocatalyst for NRR and opens up the possibility for experimentalists to further explore the carbon-based one-dimensional electrocatalyst for NRR.

Graphical abstract: Tuning surface curvature in B and N co-doped CNT-derived Fe, Ru and Ir catalysts for electrochemical hydrogenation of N2 to NH3

Supplementary files

Article information

Article type
Paper
Submitted
23 Jan 2025
Accepted
28 Apr 2025
First published
16 May 2025

Phys. Chem. Chem. Phys., 2025,27, 11221-11233

Tuning surface curvature in B and N co-doped CNT-derived Fe, Ru and Ir catalysts for electrochemical hydrogenation of N2 to NH3

D. S. Teja and B. S. Mallik, Phys. Chem. Chem. Phys., 2025, 27, 11221 DOI: 10.1039/D5CP00309A

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