The ability to efficiently and cost-effectively convert solar energy into molecular hydrogen through water splitting is necessary for meeting rising energy demands and to mitigate the adverse effects of carbon-based fuels on the environment. Earth-abundant homogeneous and hetereogeneous electrocatalysts for the hydrogen evolution reaction (HER) have been developed as alternatives to platinum, the state of the art HER catalyst whose high cost and scarcity limit wide-spread use. Hydrogenase enzymes, which catalyze reversible hydrogen production and oxidation in nature near the thermodynamic potential, have served as models for designing biomimetic catalysts for HER based on earth abundant materials. [NiFeSe] hydrogenases, a subclass of [NiFe] hydrogenase enzymes with a selenocysteine (Sec) replacing a cysteine (Cys) residue terminally bound to the Ni center, display higher activities for HER and greater O2-tolerance than the conventional sulfur only [NiFe] hydrogenases. However, the role selenium plays in these [NiFeSe] hydrogenases is currently unclear. We have recently synthesized cobalt and nickel selenolate coordination polymers based on benzene-1,2,4,5-tetraselenolate (BTSe) that catalyze HER in acidic aqueous media. The cobalt selenolate catalyst displayed ~200 mV reduction in the overpotential to reach 10 mA/cm2 in comparison to the cobalt coordination polymer based on benzene-1,2,4,5-tetrathiolate that was previously investigated in our laboratory. Mechanistic studies on the corresponding molecular complex, cobalt bis(benzenediselenolate), have allowed for further understanding into the unique role of selenium in improving HER activity. This insight will lead to the continued development of earth-abundant catalysts for practical solar to hydrogen converting devices.

Investigation of electrochemical hydrogen evolution by metal-selenolate catalysts and related mechanistic studies

254th National Meeting (2017)

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