Samarium as a Catalytic Electron-Transfer Mediator in Electrocatalytic Nitrogen Reduction to Ammonia
Samarium diiodide (SmI<sub>2</sub>) exhibits high selectivity for N<sub>2</sub>R catalyzed by molybdenum complexes; however, it has so far been employed only as a stoichiometric reagent (0.3 equiv of NH<sub>3</sub> per Sm) combined with coordinating proton sources (e.g., H<sub>2</sub>O, ROH). The latter inhibit catalytic turnover of Sm<sup>III</sup> owing to buildup of stable hydroxide/alkoxide sinks. Here, we report a tandem Sm/Mo-catalyzed <i>e</i>N<sub>2</sub>R system that achieves the lowest overpotential and highest Faradaic efficiency (82%) reported to date for nonaqueous <i>e</i>N<sub>2</sub>R at ambient pressure. Up to 8.4 equiv of NH<sub>3</sub> is produced per Sm, representing a 25-fold increase over N<sub>2</sub>R with stoichiometric SmI<sub>2</sub>. A noncoordinating proton source enables electrochemical SmI<sub>3</sub>/SmI<sub>2</sub> cycling at the applied potential of -1.45 V vs Fc<sup>+/0</sup>.
Authors
- Hoimin Jung (ORCID: https://orcid.org/0000-0002-3026-6577)
- Jonas C. Peters (ORCID: https://orcid.org/0000-0002-6610-4414)
- Emily A. Boyd (ORCID: https://orcid.org/0000-0003-0150-5396)
Institutions
- California Institute of Technology (US)
- Division of Chemistry (US)
Publication Details
- Journal
- Journal of the American Chemical Society
- Published
- 2025-01-29
- DOI
- https://doi.org/10.1021/jacs.4c14845
- Citations
- 26
- Primary Topic
- Ammonia Synthesis and Nitrogen Reduction
- Type
- article
- Field-Weighted Citation Impact
- 10.11
Funders
- National Research Foundation of Korea
- National Institute of General Medical Sciences