Ultra-thin layers of iridium electrodeposited on Ti2AlC support as cost effective catalysts for hydrogen production by water electrolysis
By Elezovi?, N. R.; Brankovi?, G.; Zabinski, P.; Marzec, M.; Jovi?, V. D.
Published in Journal of Electroanalytical Chemistry
Journal of Electroanalytical Chemistry
2020
Abstract
The hydrogen evolution reaction (HER) was investigated in 0.5 M H2SO4 at thin iridium layers electrodeposited on Ti2AlC substrate. Five samples, varying in thickness from 4.5 nm to 255 nm, were electrodeposited from the solution containing K3IrCl6 + Na2SO4. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were applied for morphology and chemical composition analysis. Metallic iridium was detected by X-ray photoelectron spectroscopy (XPS). The HER was investigated by polarization and electrochemical impedance spectroscopy (EIS) measurements. Polarization curves were characterized with the low Tafel slopes ?18 mV dec?1, while at higher current densities increased up to ?56 mV dec?1. The overpotential at j = ?0.1 A cm?2 was 45 mV, while at j = ?0.01 A cm?2 varied from 25.1 mV to 36.1 mV. These novel catalysts exhibited excellent activity, especially under industrial conditions of hydrogen production (j = ?0.3 A cm?2) - the determined overpotentials were between 66 and 69 mV only.