PNNL

Abstract

The cobalt analogue of a highly active nickel electrocatalyst for hydrogen production has been synthesized and characterized as [Co(PPh2NPh2)2(CH3CN)](BF4)2. In the presence of triflic acid in acetonitrile solution, the complex loses one cyclic diphosphine ligand to form [Co(PPh2NPh2)(CH3CN)3](BF4)2, which has been synthesized independently and stucturally characterized. The latter complex serves as an electrocatalyst for hydrogen formation with a turnover frequency of 90 sec-1 and an overpotential of 280 mV using bromoanilinium tetrafluoroborate as the acid. A similar cobalt complex with a related diphosphine ligand that does not contain a pendant base is not catalytically active, confirming an important role for the pendant amine in the catalytic reaction. This work was supported by the Chemical Sciences program of the Office of Basic Energy Sciences of the Department of Energy. The Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. Invited author, "Energy & Environmental Science", journal article.