Electrochemical CO₂Reduction over Metal-/Nitrogen-Doped Graphene Single-Atom Catalysts Modeled Using the Grand-Canonical Density Functional Theory

Electrochemical CO₂Reduction over Metal-/Nitrogen-Doped Graphene Single-Atom Catalysts Modeled Using the Grand-Canonical Density Functional Theory

Brimley, Paige (University of Colorado)
Almajed, Hussain (University of Colorado)
Alsunni, Yousef (University of Colorado; King Fahd University of Petroleum and Minerals)
Alherz, Abdulaziz W. (University of Colorado; Kuwait University)
Bare, Zachary J.L. (University of Colorado)
Smith, W.A. (TU Delft ChemE/Materials for Energy Conversion and Storage; University of Colorado)
Musgrave, Charles B. (University of Colorado)

2022

Renewably driven, electrochemical conversion of carbon dioxide into value-added products is expected to be a critical tool in global decarbonization. However, theoretical studies based on the computational hydrogen electrode largely ignore the nonlinear effects of the applied potential on the calculated results, leading to inaccurate predictions of catalytic behavior or mechanistic pathways. Here, we use grand canonical density functional theory (GC-DFT) to model electrochemical CO2 reduction (CO2R) over metal- and nitrogen-doped graphene catalysts (MNCs) and explicitly include the effects of the applied potential. We used GC-DFT to compute the CO2 to CO reaction intermediate energies at -0.3, -0.7, and -1.2 VSHE catalyzed by MNCs each doped with 1 of the 10 3d block metals coordinated by four pyridinic nitrogen atoms. Our results predict that Sc-, Ti-, Co-, Cu-, and Zn-N4Cs effectively catalyze CO2R at moderate to large reducing potentials (-0.7 to -1.2 VSHE). ZnN4C is a particularly promising electrocatalyst for CO2R to CO both at low and moderate applied potentials based on our thermodynamic analysis. Our findings also explain the observed pH independence of CO production over FeN4C and predict that the rate-determining step of CO2R over FeN4C is not *CO2- formation but rather *CO desorption. Additionally, the GC-DFT-computed density of states analysis illustrates how the electronic states of MNCs and adsorbates change non-uniformly with applied potential, resulting in a significantly increased *CO2- stability relative to other intermediates and demonstrating that the formation of the adsorbed *CO2- anion is critical to CO2R activation. This work demonstrates how GC-DFT paves the way for physically realistic and accurate theoretical simulations of reacting electrochemical systems.

COreduction
DFT calculations
electrochemistry
grand canonical density functional theory
single-atom catalysts
surface chemistry

http://resolver.tudelft.nl/uuid:6309e961-5491-49bd-96bc-43e5089bd31c

https://doi.org/10.1021/acscatal.2c01832

2023-07-01

2155-5435

ACS Catalysis, 12 (16), 10161-10171

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2022 Paige Brimley, Hussain Almajed, Yousef Alsunni, Abdulaziz W. Alherz, Zachary J.L. Bare, W.A. Smith, Charles B. Musgrave