Issue 42, 2022

Axial coordination modification of M–N4 single-atom catalysts to regulate the electrocatalytic CO2 reduction reaction

Abstract

Earth-abundant Fe, Co, Ni based single-atom catalysts (SACs) show great promise in catalyzing the electrochemical CO2 reduction reaction (CO2RR) to CO, yet the reaction activity and selectivity are still unsatisfactory. Recent experiments have witnessed great activity enhancement of M–N–C SACs by axial coordination, but the reported ligands are only limited to O, Cl and N. Various organic ligands have been widely applied in stabilizing metal nanoclusters/nanoparticles, which can, in principle, be covalently grafted onto the metal SACs. Thus rationalizing this axial modification tactic is important for the design of promising CO2RR SACs. Herein, we systematically studied MN4 (M = Fe, Co, Ni) SACs modified by a series of organic ligands via density functional theory (DFT) computations. The introduction of axial ligands can significantly affect the adsorption and reaction characteristics. The *COOH and *CO adsorption are both weakened at Fe and Co, which changes the thermodynamically most sluggish step from *CO desorption at the Fe site and CO2 adsorption at the Co site to *COOH formation. By contrast, the adsorption of *COOH is greatly enhanced while the physisorbed CO has barely changed at the Ni site, leading to greatly improved *COOH formation. The CO2RR selectivity of ligand coordinated Fe and Co is enhanced, and that of Ni is well maintained by –CH3 and –NH2. The ligand-induced regulation of the reaction thermodynamics is related to the changes in the d-band center gap of the spin state and the electron density around the Fermi level. Our findings open new avenues for developing highly effective CO2RR catalysts.

Graphical abstract: Axial coordination modification of M–N4 single-atom catalysts to regulate the electrocatalytic CO2 reduction reaction

Supplementary files

Article information

Article type
Paper
Submitted
13 Jun 2022
Accepted
25 Sep 2022
First published
27 Sep 2022

J. Mater. Chem. C, 2022,10, 15948-15956

Axial coordination modification of M–N4 single-atom catalysts to regulate the electrocatalytic CO2 reduction reaction

M. Ma and Q. Tang, J. Mater. Chem. C, 2022, 10, 15948 DOI: 10.1039/D2TC02467E

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