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 (103 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.