Eletrodeposição de revestimentos de Fex-Nix-1 de alta área e avaliação de sua atividade eletrocatalítica para a reação de desprendimento de hidrogênio em meio alcalino

Abstract

This work aims to produce porous Fe, Ni and Fe-Ni electrocatalysts for the production of hydrogen from the electrolysis of water in an alkaline medium. All electrocatalysts were prepared in an acidic soluction, under constant stirring, at a temperature of 333 K and galvanostatic electrodeposition in an aqueous soluction at a current density of 5 mA cm−2. Electrolytes containing Fe and Ni at different molar ratios were used. For morphological and electrocatalytic evaluations, the following techniques were used, respectively: scanning electron microscopy (SEM), flame atomic absorption spectrometry (FAAS), cyclic voltammetry (CV), linear scanning voltammetry (LSV) and stability tests in continuous operation. As a result, all electrocatalysts obtained presented porous surface morphology. As for the electrocatalytic tests, they all presented electrochemically active area (ECSA) values between 1107 and 6245 cm², with the electrodeposits with the highest Fe content being those with the highest value. The kinetic parameters suggest that electrodeposits with higher Fe content have more positive overpotential values and charge transfer kinetics that are more favorable to the hydrogen release reaction (RDH). Finally, stability tests suggested good adhesion of the electrodeposits during an operating time of 40 hours and a temperature of 333 K, with potential values remaining stable between –200 and –400 mV.