Anodic Treatment of Ni-Cu Alloy in a Deep Eutectic Solvent to Improve Electrocatalytic Activity in the Hydrogen Evolution Reaction

Abstract

The quality of the Souss-Massa Daraa (S-MD) aquifer is influenced by natural and anthropogenic contaminations. Indeed, geological formations are the main sources of mineralization in the aquifer, which compromises the potential irrigation, and threatens the sustainability of agricultural activities. In this context, hydrochemical and statistical studies were carried out on the major and secondary elements of water, based on different physico-chemical parameters, such as T °C, pH, EC (electric conductivity), NO3 -(nitrate), Cl -(chloride), HCO3 -(bicarbonate), SO4 2-(sulfate), Ca 2+ (calcium ions), Mg 2+ (magnesium ions), K+ (potassium ion), Na + (sodium), Na%, Mg% and SAR (sodium adsorption ratio). The sampling was carried out in 2018, over two seasons (winter and summer), by analyzing 26 wells distributed over the studied plain. According to the water classification based on EC, it was found that 80% of the samples show very high mineralization, and 96.66% are very hard and unfit for human consumption. Also, Clvalues of most of the samples were within limits inappropriate for irrigation, but some estimated parameters, such as Na% and SAR, were within appropriate levels. In addition, according to the piper diagram, the waters are characterized by a geochemical facies of 86.66% NaCl (sodium chloride), 13.33% CaSO 4 (sulphated calcium) and Mg. Thus, the principal component analysis (PCA) shows that the region waters mineralization is of natural origin.

Application of Deep Eutectic Solvents to Prepare Electrocatalysts for Green Hydrogen Production

“…The experimental results demonstrated that the anodic modification of the Cu-Ni alloy surface in DESs induces notable alterations in its electrocatalytic behaviour towards the HER in an aqueous alkaline solution [4][5][6]. As is known, the exchange current density of an electrochemical reaction is a measure of electrocatalytic activity.…”

“…Two representatives of DESs were used: ethaline and reline (eutectic mixtures of choline chloride with ethylene glycol and urea, respectively). The methods for the ethaline and reline preparation have been described in numerous literature sources, including our previous publications [4][5][6][7][8][9][10].…”

“…A copper-nickel alloy (45 wt.% Cu) was used as an object for anodic treatment in DESs [4][5][6]. To perform cathodic modification of the nickel-based electrocatalyst surfaces, their chemical composition was modified (micromodified) through the incorporation of alloying components during electrodeposition.…”

“…Salts of nickel (II), iron (II), molybdenum (VI), cerium (III), and lanthanum (III) were dissolved in either ethaline or reline to fabricate the plating electrolytes. Detailed information regarding the preparation of electrolytes and the electrochemical deposition procedures can be found in publications [4][5][6][7][8][9][10]. The electrocatalytic activity of the resulting catalysts was assessed for the HER in an alkaline aqueous solution of 1 M NaOH at a temperature of 298 K. The evaluation was performed using techniques such as linear/cyclic voltammetry and electrochemical impedance spectroscopy.…”

A Comparison between Porous to Fully Dense Electrodeposited CuNi Films: Insights on Electrochemical Performance

“…This is due to the surface composition and spatial arrangement exerting a remarkable influence on the hydrogen adsorption and desorption. Protsenko and coworkers demonstrated that the surface inhomogeneity of CuNi alloy will lead to unexpected HER behaviors and it is revealed that the structure and morphology are the reasons for improving the hydrogen evolution performance of the anodic-treated Ni-Cu alloy [ 33 , 34 ]. Despite the numerous studies performed regarding the beneficial effect of porous structure on HER performance, the reported data are, in some cases, inconsistent across different investigations.…”