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An iron complex with pendent amines as a molecular electrocatalyst for oxidation of hydrogen

Nature Chemistry volume 5, pages 228–233 (2013)Cite this article

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Abstract

The increasing energy needs of society have led to a search for technologies that can tap carbon-neutral and sustainable energy sources, such as solar and wind. Using properly designed catalysts, such sources can also be used to create fuels such as hydrogen; however, a significant barrier to the use of hydrogen as an energy carrier is the need for an inexpensive and efficient catalyst for its oxidation. The oxidation of hydrogen is the process by which electricity is produced in low-temperature fuel cells, and the best catalyst for this is platinum—a precious metal of low abundance. Here we report a molecular complex of iron (an abundant and inexpensive metal) as a rationally designed electrocatalyst for the oxidation of H2 at room temperature, with turnover frequencies of 0.66–2.0 s−1 and low overpotentials of 160–220 mV. This iron complex, , has pendent amines in the diphosphine ligand that function as proton relays.

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Figure 1: Synthetic reactions used to prepare iron complexes.
Figure 2: Molecular structures of [ (1-Cl) and [ (1-H) determined by X-ray crystallography.
Figure 3: Electrochemical studies of iron complexes at 22 °C.
Figure 4: Cyclic voltammograms of a fluorobenzene solution of 1-H (1.0 mM).
Figure 5: Proposed mechanism for electrocatalytic oxidation of H2.

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Acknowledgements

The authors acknowledge support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, for the initial parts of this work. Current work is supported by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. The authors thank J.A.S. Roberts for advice on the open-circuit potential measurements.

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  1. Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, PO Box 999, K2-57, Richland, 99352, Washington, USA

    Tianbiao Liu, Daniel L. DuBois & R. Morris Bullock

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  1. Tianbiao Liu
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D.L.D., R.M.B. and T.L. designed and interpreted the experiments and wrote the paper. All experiments were performed by T.L.

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Correspondence to R. Morris Bullock.

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Supplementary information

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Supplementary information (PDF 2958 kb)

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Crystallographic data for compound 1-CL. (CIF 57 kb)

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Crystallographic data for compound 1-H. (CIF 56 kb)

Supplementary information

Crystallographic data for compound Fe(P t Bu N Bn )Cl 2 . (CIF 56 kb)

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Liu, T., DuBois, D. & Bullock, R. An iron complex with pendent amines as a molecular electrocatalyst for oxidation of hydrogen. Nature Chem 5, 228–233 (2013). https://doi.org/10.1038/nchem.1571

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