Stability Study of Materials for Electrode Supports for the Hydrogen Generation from a NaCl Aqueous Solution

Abstract

The hydrogen generation by electrolysis from seawater is one of the most promising processes for this fuel production, avoiding the use of highly dangerous KOH solution as electrolyte. There are many problems associated with this process, such as the low electrochemical efficiency and the high corrosion capacity of chloride ions present in seawater. In this work, different materials proposed as possible electrodes or electrode supports in a NaCl solution are physicochemically analyzed from a comparative point of view. Corrosion studies by salt fog testing, Raman spectroscopy, X-ray diffractometry, and electrochemical analysis were carried out in this medium, and the catalytic efficiencies towards the electrochemical hydrogen generation were comparatively evaluated. Thus, samples of Ti, Ni, AISI 316L stainless steel, and Cu showed important hydrogen current in the analyzed potentials range. Their results recorded by cyclic voltammetry and electrochemical impedance spectroscopy, in addition to the Tafel plots, confirmed to be good active catalysts for hydrogen evolution reaction. On the other hand, materials as Al and carbon cloth show moderate and low corrosion in this medium and can be used as catalysts supports. It is found that nickel not only has a high tolerance to chloride ions but also presents the highest electrochemical efficiency. Its current density at −1.5 VSCE is 3.22 × 10–2 A cm−2, followed in order by AISI 316L stainless steel with high Ni content (1.33 × 10–2 A cm−2), concluding that Ni samples constitute the appropriate material for cathodes to be used in electrolyzers working with seawater.