Tunability of Nickel Benzenehexathiolate Electrocatalysts for the Hydrogen Evolution Reaction

Dithiolene-based coordination polymers synthesized using earth-abundant transition metals have been rigorously explored for sustainable energy applications, such as solar-to-fuel conversion. The strategy of embedding molecular catalysts into extended frameworks is expected to improve the catalytic performance and reusability of the catalysts. Here, we investigate nickel benzenehexathiolate (NiBHT) frameworks as electrocatalysts to facilitate the hydrogen evolution reaction (HER) in acidic aqueous conditions. NiBHT coordination polymers synthesized with different morphologies and porosity were investigated to determine the essential features for developing efficient electrocatalysts for HER. The nonporous NiBHT coordination polymer in nanoparticle morphology exhibited enhanced electrochemical activity with an onset potential of -128 mV and an overpotential of 225 mV at 10 mA/cm². The 2 h controlled potential electrolysis of this electrocatalyst achieved a Faradaic efficiency of 90%, suggesting that the dithiolene-based electrode materials containing nickel ions are an efficient electrocatalyst for the hydrogen evolution reaction.