Electrochemical hydrogen production in aqueous micellar solution by a diiron benzenedithiolate complex relevant to [FeFe] hydrogenases

The diiron hydrogenase model Fe-2(bdt)(CO)(6) (1, bdt = benzenedithiolate) was dispersed in an aqueous micellar solution prepared from sodium dodecyl sulfate (SDS). The aqueous solution of 1 showed no sign of decomposition when left in contact with air over a period of several days. Current-potential responses recorded at a dropping mercury electrode over pH 7-3 were consistent with reduction of freely diffusing species. Catalysis of proton reduction was observed at pH < 6 with current densities exceeding 0.5 mA cm(-2) at an acid-to-catalyst ratio of 17. Bulk electrolysis at -0.66 V vs. SHE of a solution of 1 at pH 3 confirmed the production of hydrogen with Faradaic efficiency close to 100%. A mechanism involving initial reduction of 1 and subsequent proton-coupled electron transfer is proposed.