Elucidating the Intrinsic CO2RR performance at MN4 sites using Morphologically Comparable M-N-Cs
- Metal- and nitrogen-doped carbons (M-N-Cs) are a promising class of low-cost electrocatalysts derived from earth-abundant elements for various electrochemical applications including ORR and CO2RR [1,2]. Traditionally, M-N-Cs containing active metals (M = Fe, Co, and Ni) are synthesized through direct pyrolysis of inorganic and organic precursors. However, this process often leads to the undesired formation of inorganic side phases via carbothermal reduction, hindering both the efficient incorporation of active metal and the intrinsic activity comparison among active sites.
To overcome these challenges, we developed an active-site imprinting strategy where active metals are introduced post-pyrolysis through ion-exchange [3-5]. In this work, we applied a Mg imprinting strategy to synthesize Co-N-Cs and Ni-N-Cs with comparable morphology and metal dopant concentrations, enabling a more direct comparison of their intrinsic activities. Notably, Ni-N-Cs produced via this method consistentlyMetal- and nitrogen-doped carbons (M-N-Cs) are a promising class of low-cost electrocatalysts derived from earth-abundant elements for various electrochemical applications including ORR and CO2RR [1,2]. Traditionally, M-N-Cs containing active metals (M = Fe, Co, and Ni) are synthesized through direct pyrolysis of inorganic and organic precursors. However, this process often leads to the undesired formation of inorganic side phases via carbothermal reduction, hindering both the efficient incorporation of active metal and the intrinsic activity comparison among active sites.
To overcome these challenges, we developed an active-site imprinting strategy where active metals are introduced post-pyrolysis through ion-exchange [3-5]. In this work, we applied a Mg imprinting strategy to synthesize Co-N-Cs and Ni-N-Cs with comparable morphology and metal dopant concentrations, enabling a more direct comparison of their intrinsic activities. Notably, Ni-N-Cs produced via this method consistently demonstrated superior activity and selectivity compared to isomorphic Co-N-Cs, achieving CO Faraday efficiencies of up to 95% at relatively low overpotentials. Furthermore, the Ni-N-C catalyst exhibited excellent stability at -0.65 VRHE, retaining 92.5% of its current density and 97.6% of its CO selectivity after 100 hours of continuous operation.
A distinct advantage of the imprinting strategy lies in the suppression of inorganic side phases, enabling an accurate local structure characterization of the porphyrin-like tetrapyrrolic MN4 coordination structure using Extended X-ray Absorption Fine Structure (EXAFS). The characterization of the tetrapyrrolic NiN4 site is especially puzzling, as density functional theory (DFT) simulations often predict these sites to be inert to both CO2RR and HER. Drawing on recent studies which highlight the crucial role of cations for CO2RR on noble metal catalysts like Cu, Ag and Au [6-7], we performed mechanistic investigations using DFT to extend the relevance of cations to the CO2RR/HER performance at the MN4 sites, and further illustrate the advantage of the pyrrolic N atoms in anchoring them near the active metals.…


| Autor*innen: | Jian Liang LowORCiD |
|---|---|
| Koautor*innen: | Tim-Patrick FellingerORCiD, Asad Mehmood, Simon Dietzmann |
| Dokumenttyp: | Vortrag |
| Veröffentlichungsform: | Präsentation |
| Sprache: | Englisch |
| Jahr der Erstveröffentlichung: | 2025 |
| Organisationseinheit der BAM: | 3 Gefahrgutumschließungen; Energiespeicher |
| 3 Gefahrgutumschließungen; Energiespeicher / 3.6 Elektrochemische Energiematerialien | |
| DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Angewandte Physik |
| Freie Schlagwörter: | Active-site imprinting; Electrochemical CO2 reduction; Metal- and Nitrogen-doped Carbon (M-N-C); Single Atom Catalyst |
| Themenfelder/Aktivitätsfelder der BAM: | Energie |
| Energie / Elektrische Energiespeicher und -umwandlung | |
| Veranstaltung: | 4th Conference of the GDCh Division of Chemistry and Energy |
| Veranstaltungsort: | Duisburg, Germany |
| Beginndatum der Veranstaltung: | 09.04.2025 |
| Enddatum der Veranstaltung: | 10.04.2025 |
| Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |
| Datum der Freischaltung: | 15.12.2025 |
| Referierte Publikation: | Nein |
| Eingeladener Vortrag (wissenschaftliche Konferenzen): | Nein |

