Electrocatalytic Hydrogen Evolution by Cobalt Complexes with a Redox Non-Innocent Polypyridine Ligand

Liu J, Liao RZ, Heinemann FW, Meyer K, Thummel RP, Zhang Y, Tong L (2021)


Publication Type: Journal article

Publication year: 2021

Journal

DOI: 10.1021/acs.inorgchem.1c02539

Abstract

Novel cobalt and zinc complexes with the tetradentate ppq (8-(1″,10″-phenanthrol-2″-yl)-2-(pyrid-2′-yl)quinoline) ligand have been synthesized and fully characterized. Electrochemical measurements have shown that the formal monovalent complex [Co(ppq)(PPh3)]+ (2) undergoes two stepwise ligand-based electroreductions in DMF, affording a [Co(ppq)DMF]-1 species. Theoretical calculations have described the electronic structure of [Co(ppq)DMF]-1 as a low-spin Co(II) center coupling with a triple-reduced ppq radical ligand. In the presence of triethylammonium as the proton donor, the cobalt complex efficiently drives electrocatalytic hydrogen evolution with a maximum turnover frequency of thousands per second. A mechanistic investigation proposes an EECC H2-evolving pathway, where the second ligand-based redox process (E), generating the [Co(ppq)DMF]-1 intermediate, initiates proton reduction, and the second proton transfer process (C) is the rate-determining step. This work provides a unique example for understanding the role of redox-active ligands in electrocatalytic H2 evolution by transition metal sites.

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APA:

Liu, J., Liao, R.Z., Heinemann, F.W., Meyer, K., Thummel, R.P., Zhang, Y., & Tong, L. (2021). Electrocatalytic Hydrogen Evolution by Cobalt Complexes with a Redox Non-Innocent Polypyridine Ligand. Inorganic Chemistry. https://doi.org/10.1021/acs.inorgchem.1c02539

MLA:

Liu, Jiale, et al. "Electrocatalytic Hydrogen Evolution by Cobalt Complexes with a Redox Non-Innocent Polypyridine Ligand." Inorganic Chemistry (2021).

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