Produção de hidrogênio catalisada por revestimento de Ni-Fe eletrodepositados a partir de uma mistura eutética de cloreto de colina e ureia

Abstract

The search for renewable energy sources has driven the development of clean technologies, such as the creation of green hydrogen via water electrolysis. This study focused on the production and analysis of metallic coatings of nickel (Ni) and nickel-iron alloys (Ni-Fe) by electrodeposition in a deep eutectic solvent (DES) composed of choline chloride and urea (1ChCl:2U), aiming at their use in the hydrogen production reaction (HER). Initially, the electrochemical action of Ni²􁁰 and Fe³􁁰 ions in DES solution at 60 °C was analyzed by cyclic voltammetry, followed by the deposition of the coatings on copper electrodes, with variation in the presence of iron in the electrolytic baths. The electrodeposited layers were characterized by morphological analysis using a scanning electron microscope, chemical analysis using energy dispersive spectroscopy, and electrochemistry analysis using linear polarization curves and Tafel curves. The results showed that the addition of iron promoted a normal deposition behavior, altering the surface morphology and favoring the increase of the active area. Electrodes coated with Ni-Fe combinations demonstrated superior electrocatalytic performance compared to pure nickel and copper, with emphasis on the Ni84-Fe16sample, which presented the lowest overpotential (81.91 ± 9.60 mV), and Ni92-Fe08, which exhibited the lowest Tafel slope (93.50 ± 3.98 mV dec􁁱¹), revealing more favorable kinetics for HER. The data gathered confirm the potential of using DES as an alternative and sustainable means for the creation of electrocatalysts, aiding in the production of hydrogen in a clean, efficient and economical manner, in addition to strengthening the applicability of Ni-Fe combinations in electrochemical systems focused on the energy transition