Electrocatalytic Performance of Thiacalix[4]arene-based Co(II) Complex in Hydrogen Evolution Reaction

Abstract

The generic electron-rich thiacalix[4]arene bearing sulfur and oxygen coordinating donor atoms in the lower rim is underestimated as a pre-catalyst for the Hydrogen Evolution Reaction (HER). In addition, cobalt is a promising metal ion for many electrocatalytic applications, including HER. Herein, we report the electrocatalytic activity of a cobalt(II) compound based on thicalix[4]arene that was characterized by cyclic voltammetry (CV). The CV using the glassy carbon as a working electrode versus Ag/AgCl, show two reduction peaks at -0.582 V and -1.270 V for the two redox couples Co2+/Co+ and Co+/Co, respectively. The two-electron proton reduction into hydrogen in the presence of the catalyst and 5 equivalents (12.5 mM) of acetic acid show a noticeable shift of about 780 mV compared to the catalyst-free reaction and 200 mV compared to the second wave observed for the acid-free solution. Moreover, a maximum anodic peak current of 32 µA was observed upon adding 30 equivalents (75 mM) of acetic acid.