Novel peripheral and non-peripheral oxobenzo[d]thiazol substituted cobalt phthalocyanines: Synthesis, electrochemistry, spectroelectrochemistry, electrocatalytic hydrogen production in alkaline medium

Abstract

In this study novel oxobenzo[d]thiazol substituted cobalt phthalocyanine complexes were synthesized and characterized by FT-IR, NMR, UV-vis spectroscopy, and mass spectrometry. The redox properties of peripheral and non-peripheral substituted CoPc complexes were determined and compared via electrochemical characterization. The reduction-oxidation transitions of the metal and the ring were recorded with in-situ spectroelectrochemical measurements. Electrocatalytic activity of complexes were investigated in alkaline medium for hydrogen evolution reaction. The CoPc complexes exhibited excellent electrocatalytic activity in presence of graphene oxide. The GO/3N-CoPc and GO/4N-CoPc displayed low overpotential of 330 mV at 10 mA cm-2 with Tafel slope of 64 mV dec-1, which superior in comparison with the CoPc (overpotential of 497 mV at 10 mA cm-2). Moreover, GO/3N-CoPc and GO/4N-CoPc electrocatalysts exhibited similar to 53 times higher catalytic current density than bare GCE.