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Acidic ionic liquid/water solution as both medium and proton source for electrocatalytic H₂ evolution by [Ni(P₂N₂)₂]²⁺ complexes
- Pool, Douglas H., Stewart, Michael P., O’Hagan, Molly, Shaw, Wendy J., Roberts, John A. S., Bullock, R. Morris, DuBois, Daniel L.
- Proceedings of the National Academy of Sciences of the United States of America 2012 v.109 no.39 pp. 15634-15639
- acetonitrile, aqueous solutions, bromine, catalysts, evolution, hydrogen, hydrogen production, hydrophobicity, ionic liquids, nickel, protons
- The electrocatalytic reduction of protons to H ₂ by [Formula] (where [Formula] in the highly acidic ionic liquid dibutylformamidium bis(trifluoromethanesulfonyl)amide shows a strong dependence on added water. A turnover frequency of 43,000–53,000 s ⁻¹ has been measured for hydrogen production at 25 °C when the mole fraction of water (χ H₂O) is 0.72. The same catalyst in acetonitrile with added dimethylformamidium trifluoromethanesulfonate and water has a turnover frequency of 720 s ⁻¹. Thus, the use of an ionic liquid/aqueous solution enhances the observed catalytic rate by more than a factor of 50, compared to a similar acid in a traditional organic solvent. Complexes [Formula] (X = H, OMe,CH ₂P(O)(OEt) ₂, Br) are also catalysts in the ionic liquid/water mixture, and the observed catalytic rates correlate with the hydrophobicity of X .