Electrochemical Study of the Hydrogen Evolution Reaction using Coppe r(II) Thiacalix[4]arene-based Catalyst

Despite the interesting structure of the generic thiacalix[4]arene containing four coordinating sulfur atoms bridging four phenolic units, there are only a few reported examples of thiacalixarene-based coordination complexes that are used as electrocatalysts. Herein, we report electrocatalytic hydrogen evolution reaction (HER) by a thiacalix[4]arene-based copper(II) complex (1). As expected, two reduction waves were appeared (-0.48 V and-1.30 V vs Ag/AgCl) for Cu2+/Cu+ and Cu+/Cu reduction couples. The HER by proton reduction occurs at-1.03 V with a shift of 0.27 V compared to the second peak potential at-1.30 V. The increase in the number of acetic acid equivalents, from 0 to 17.5 with a frequency of 2.5 eq, was accompanied by an increase in the peak current that reached a maximum value of 183 mu A for 15 equivalents of acetic acid.