Eletrodeposição e caracterização de revestimentos de Ni obtidos a partir de solvente eutético profundo aplicados para eletrocatálise de reações de evolução de hidrogênio

Abstract

Green hydrogen has gained significant attention in the global scenario due to environmental challenges and the reliance on a predominantly fossil fuel-based energy matrix. In this context, the production of green hydrogen through water electrolysis, using renewable energy sources, emerges as a viable alternative to promote a more sustainable energy transition. However, its production faces challenges, as the water electrolysis process is kinetically slow, requires high energy consumption, and depends on efficient electrocatalysts to reduce these costs. Therefore, this study aims to develop efficient and cost-effective electrocatalysts for water electrolysis processes. To achieve this, the electrodeposition of nickel (Ni) onto copper (Cu) was investigated using a deep eutectic solvent (DES) composed of calcium chloride (CaCl₂) and ethylene glycol (EG) in a 1:8 molar ratio. The methodology included electrochemical and morphological characterization techniques, such as cyclic voltammetry (CV), scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and linear polarization curves. The CV results demonstrated that the DES exhibited a stable electrochemical window in the potential range of –0.5 V to –1.25 V. The voltammograms obtained for nickel deposition indicated that the peak potential favored higher reduction efficiency, resulting in accelerated deposition kinetics, particularly at 80 °C. SEM analyses revealed the formation of Ni films with a characteristic "cauliflower-like" morphology, while EDS confirmed the presence of Ni and Cu on the deposited surface. Linear polarization curves showed that all evaluated parameters exhibited similar profiles, with the coating obtained at the peak potential (–0.76 V) demonstrating the highest catalytic activity. The results concluded that the electrodeposition of Ni onto Cu in DES is a promising approach for synthesizing efficient electrocatalysts, with potential applications in green hydrogen production, contributing to the reduction of energy costs associated with water electrolysis