International Journal of Hydrogen Energy, Vol.44, No.23, 11431-11440, 2019
Hydrogen evolution reaction enhanced by water-soluble metallopyridinoporphyrazine complex adsorbed on highly oriented pyrolytic graphite
The ultrathin (similar to 2 nm) film of N,N',N '',N'''-tetramethyltetra-3,4-pyridino-porphyrazinato-cobalt(II) complex adsorbed on the basal plane of highly oriented pyrolytic graphite (HOPG/Co(I)Tmtppa) was used as a mediator for electrocatalytic hydrogen evolution reaction (HER) in a wide range of pH. The Co(I)Tmtppa film was characterized by in-situ backscattering spectroscopy, atomic force microscopy and cyclic voltammetry. Electrocatalytic measurements of HOPG/Co(I)Tmtppa electrode using voltammetric techniques showed up to 60 fold increase of current density and overpotential decreased by 300 mV, compared to the bare HOPG electrode at pH 11 and confirmed very good stability with only 8% deviation over 1000 cycles. The Tafel analysis indicated the Volmer-Heyrovsky mechanism of hydrogen evolution reaction with hydrogen adsorption rate-determining step at all pH values. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.