Electrocatalytic hydrogen evolution by metal organic complexes fe co and ni

Abstract

Non-noble transition metal-organic complexes were synthesized by a simple one-step process. In this work metals such as Ni, Fe, and Co were used as metal sources. The ligands that are commercially available, stable, and do not oxidize easily were used to prepare metal-organic complexes. In this study, quinazoline thione, benzimidazole, benzothiazole, and curcumin-based compounds were used as ligand sources. The complexes are fabricated onto the Ni foam and glassy carbon electrode (conductive substrate), which act as an electrocatalyst during the electrochemical water splitting process. Linear sweep voltammetry (LSV) was carried out to find the negative reduction potential at which the hydrogen gas evolves. The LSV plot is further interpreted by taking the logarithm of the current density obtained versus the reduction overpotential. The transition metal centered as prepared Ni, Fe and Co organic ligand based complexes were discussed in this work. newlineFor developing 4-(4-chlorophenyl)-3,4,5,6-tetrahydrobenzo [h] quinazoline-2(1H)-thione based nickel complex, a Biginelli type reaction was carried out by using NiCl2.6H2O as precursor. The prepared electrocatalyst was analytically characterized using UV-Vis, FT-IR, Mass, 1H and 13C NMR and SEM-EDX spectroscopy. When analyzed the HER activity of the Ni-quinazoline complex compared with Pt/C (both fabricated on glassy carbon electrode) by performing LSV experiments, a low Tafel slope of 34 mV/dec for Ni complex and 38 mV/dec for Pt/C was observed in 1 M phosphate buffer solution, respectively. In 0.5M H2SO4 acidic electrolyte, a Tafel slope of 100 mV/dec was obtained for Ni complex while Pt/C showed a Tafel slope of 50 mV/dec. newline