Conductive Copper Benzenehexathiol Coordination Polymer as a Hydrogen Evolution Catalyst

A graphene-like coordination polymer based on copper(II) benzenehexathiol (Cu-BHT, 1 ) with high electric conductivity (10 3 S·cm –1 ) was prepared recently. The high conductivity makes this material a good candidate for electrocatalysis, and here its catalytic activity toward hydrogen evolution reaction (HER) was evaluated. Cu-BHT shows good activity and stability for HER in acidic solutions under high current densities. By changing the preparation conditions, the morphology of Cu-BHT materials was controlled at the mesoscale, which allows the preparation of a thin film (TF- 1 ), nanocrystal (NC- 1 ), and amorphous nanoparticle (NP- 1 ) of Cu-BHT. The overpotential of Cu-BHT toward HER shows an improved activity from 760 mV (NC- 1 ) to 450 mV (NP- 1 ) at a current density of 10 mA·cm –2 . A Tafel slope of ∼95 mV·dec –1 and an exchange current density of 10 –3 mA·cm –2 were achieved under optimized conditions. Density functional theory calculations suggest that the “Cu-edge site” on the (100) surface plays an important role in improving the HER catalytic performance of Cu-BHT nanoparticles.