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. 2025 Apr 16;147(15):13027-13038.
doi: 10.1021/jacs.5c03121. Epub 2025 Apr 1.

Adapting Atomic Configuration Steers Dynamic Half-Occupied State for Efficient CO2 Electroreduction to CO

Jiali Wang  1 , Hui Ying Tan  1 , Chia-Shuo Hsu  2 , You-Chiuan Chu  1 , Ching-Wei Chan  1 , Kuan-Hsu Chen  1 , Xuan-Rou Lin  1 , Yi-Chun Lee  1 , Hsiao-Chien Chen  3 , Hao Ming Chen  1   2   4
Affiliations

Adapting Atomic Configuration Steers Dynamic Half-Occupied State for Efficient CO2 Electroreduction to CO

Jiali Wang et al. J Am Chem Soc. .

Abstract

Electronic structures stand at the center to essentially understand the catalytic performance and reaction mechanism of atomically dispersed transition-metal-nitrogen-carbon catalysts (ADTCs). However, under realistic electrocatalytic conditions, the dynamic electronic disturbance at metal centers originating from complicated interactions with microenvironments is commonly neglected, which makes a true structure-property correlation highly ambiguous. Here, we employ operando time-resolved X-ray absorption spectroscopy to delve deeply into dynamic electronic behaviors of a family of transition-metal centers that are observed to adaptively vary in the metal-ligand configuration during the CO2 electroreduction reaction. We identify dynamic electronic/geometric configuration and d-orbital occupation under working conditions, demonstrating an unprecedentedly precise activity descriptor, i.e., dynamic axial dz2 electron, for the CO2-to-CO conversion. Direct results validate that the half-occupied state suggests the optimum binding behaviors with intermediates, significantly promoting CO production, which has been demonstrated by a significant kinetics enhancement of 1 to 2 orders of magnitude as compared with fully occupied and unoccupied states. This work presents the first empirical demonstration for a real correlation between the dynamic electronic/geometric configuration and catalytic kinetics in ADTCs, paving a new way for modulating catalysts and designing highly efficient reaction pathways.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Structural characterizations of various ADTCs. (a) Schematic illustration of the formation of various ADTCs. (b) Fourier transformed (FT) k3-weighted metal K-edge extended X-ray absorption fine structure (EXAFS) spectra of various ADTCs. (c) N K-edge X-ray absorption near-edge structure (XANES) spectra of various ADTCs. (d) Metal L-edge XANES spectra of various ADTCs.
Figure 2
Figure 2
Dynamic structural evolutions during CO2RR. Operando time-resolved metal K-edge EXAFS spectra for (a) Mn, (b) Ni, (c) Fe, (d) Co, (e) Cu, and (f) Zn ADTCs under CO2RR conditions.
Figure 3
Figure 3
Electrocatalytic properties of CO2-to-CO conversion. (a) Correlation between the overall CN around various metal centers in ADTCs and partial current density of CO production at different applied potentials. (b) Tafel plots of various ADTCs toward CO production during CO2RR.
Figure 4
Figure 4
Dynamic electronic behaviors of various metal sites in ADTCs during CO2RR. Δμ analysis of operando time-resolved metal K-edge XANES spectra for (a) Mn, (b) Ni, (c) Fe, (d) Cu, (e) Co, and (f) Zn ADTCs under CO2RR conditions. Δμ analysis presents a subtraction methodology according to Δμ = μ(applied potential) – μ(OCV). MLCT: metal-to-ligand charge transfer, LMCT: ligand-to-metal charge transfer.
Figure 5
Figure 5
Correlation between dynamic d orbital and CO kinetics. A double volcano-shaped relationship between the electron numbers in dynamic d orbitals and CO partial current density. jCO is evaluated with progressively cathodic potentials, color-coded from light to dark. The potential range is −0.35 to −0.85 VRHE for Mn, Ni, and Zn, −0.35 to −0.65 VRHE for Fe and Co, and −0.55 to −0.85 VRHE for Cu. Potential interval: 0.1 V. The upper potential bounds chosen in this figure represent the highest potential that the atomic configuration of metal sites was able to sustain without rupture of M–N bonds and formation of metal clusters.
Figure 6
Figure 6
Dynamic orbital understandings of various transition-metal sites during CO2RR. Dynamic 3d orbital reorganization and electron filling in terms of various metal–ligand interaction configuration evolutions for ADTCs during CO2RR.
Figure 7
Figure 7
Proposed activity descriptor toward CO2RR. CO partial current density of various ADTCs as a function of the dynamic dz2 orbital occupation. The jCO data with progressively cathodic potentials, color-coded from light to dark, are extracted from Figure 5. The potential range is −0.55 to −0.85 VRHE for Mn, −0.55 to −0.65 VRHE for Fe, −0.35 to −0.65 VRHE for Co, −0.65 to −0.85 VRHE for Ni, −0.55 to −0.85 VRHE for Cu, and −0.35 to −0.85 VRHE for Zn. Potential interval: 0.1 V. The lower potential bounds represent the lowest potential that the metal sites obtain the dynamically stable oxidation/spin states and atomic configuration during CO2RR, and the upper potential bounds represent the highest potential that the atomic configuration of metal sites was able to sustain without rupture of M–N bonds and formation of metal clusters.
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