Preprint

PUBDB-2025-05266

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Revealing the dynamic changes of FeNC during CO$_2$RR: An integrated approach

Segura-Salas, N. ; Misra, D. ; Heppe, N.Extern* ; Azimov, P.Extern* ; Paidi, V. K. ; Haak, H.Extern* ; Theis, P.Extern* ; Jiang, L.Extern* ; Sergeev, I.XFEL.EU*DESY* ; Krewald, V. (Corresponding author) ; Kramm, U. (Corresponding author)Extern*

2025

This record in other databases:    

Please use a persistent id in citations: doi:10.26434/chemrxiv-2025-0bgj8  doi:10.3204/PUBDB-2025-05266

Abstract: We explored the electrochemical behaviour of an iron-nitrogen-carbon catalyst in the electrochemical CO$_2$ reduction reaction (CO$_2$RR). The catalyst was prepared by pyrolysis from carbon-supported iron porphyrin to ensure a high concentration of FeN$_4$ moieties and low amount of side phases. In situ X-ray absorption spectroscopy and X-ray emission spectroscopy were applied to determine average oxidation state, average spin state for the ex situ catalyst, electrode and various potential conditions. Nuclear forward scattering enabled us to determine the hyperfine interaction parameters associated with all individual iron coordination sites for different potentials as well as ex situ. Together with DFT calculations, this approach enabled us to discriminate the contributions of pyridinic and pyrrolic FeN$_4$ moieties in the catalyst. Control experiments (without CO$_2$ saturation) showed the formation of a pyrrolic ferryl FeN$_4$ moiety with an oxygen ligand, caused by the unavoidable presence of oxygen from air. This intermediate belongs to the oxygen reduction reaction cycle that we elucidated in our previous work (doi: 10.1021/jacs.2c04865). In the presence of CO$_2$, however, the main changes are associated with pyridinic FeN$_4$ moieties. Aided by the identification of different intermediates, we deduce a CO$_2$RR mechanism for the relevant pyridinic FeN$_4$ moieties.

---

Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. PETRA-S (FS-PETRA-S)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
3. DFG project G:(GEPRIS)443703006 - SFB 1487: Eisen, neu gedacht! (443703006) (443703006)
4. FS-Proposal: I-20221267 (I-20221267) (I-20221267)

Experiment(s):

1. PETRA Beamline P01 (PETRA III)

Appears in the scientific report 2025

---

Database coverage:
;

---