Electrodeposition of Fe–Co Alloys from a Glycinate Solution and Their Evaluation as Cathode Materials for the Hydrogen Evolution Reaction

The influence of the composition of a glycinate electrolyte on the formation of electrodeposited Fe–Co alloys from acidic solutions on steel and brass substrates was investigated. Alloy deposition was performed by polarizing the electrodes at current densities of 10 and 20 mA/cm2. By X‑ray fluorescence, the effects of the iron-to-cobalt ion ratio in the solution, glycine (Gly) concentration, and boric acid concentration on the chemical composition of the electrodeposited Fe–Co alloys were determined. The positive effect of glycine and boric acid on the formation of uniform Fe–Co coatings with satisfactory adhesion to the substrate was demonstrated. The electrodeposited alloys were studied by X‑ray phase analysis (XRD), gravimetric analysis, and chronovoltamperometry. For the obtained Fe–Co alloys, correlations were established between the coatings’ chemical composition and their microhardness and corrosion resistance in a 3% NaCl solution. The dependence of the physicochemical properties of the Fe–Co alloys on their phase composition was shown: the highest corrosion resistance was observed for the alloy with composition 38 wt % Fe and 62 wt % Co, containing CoFe and Fe3Co7 phases. The effect of deposition current and the concentrations of iron and cobalt ions in the electrolyte on the catalytic activity of the Fe–Co coatings for the electrochemical hydrogen evolution reaction in 1 M NaOH was studied. The stability of the Fe–Co alloy performance in alkaline solution was evaluated by chronopotentiometry.