Electrodeposition of Alloy Nanostructures (Co-Ni) in the Presence of Sodium Benzene Sulfonate (SBS) and Their Application in Alkaline Hydrogen Evolution

The galvanostatic electrodeposition of cobalt-nickel alloy coatings performed out on a 304 stainless steel substrate. The electrolyte baths contained metals salts, along with boric acid and sodium benzene sulfonate (SBS) as an organic additive in the deposition process. Structural and topographic analyses were performed using SEM-EDS and AFM techniques, respectively. The findings confirm the formation of nanostructured coatings. The images depicting various stages of coating formation indicated the inhibitory role of the organic additive. The presence of SBS enabled the formation of a coating composed of grains with diverse geometries and significantly reduced surface roughness. Hydrogen evolution was conducted in an alkaline environment (1 M NaOH). Overpotentials for the different structures were recorded at 10 mA/cm², yielding 196 mV and 225 mV for the coatings deposited with and without SBS, respectively. Additionally, experiments were performed in a laboratory-designed electrolyzer, which allowed for the measurement of gas volumes (H₂ and O₂) generated under constant voltage and current conditions. The results demonstrated that the obtained coatings perform more effectively as hydrogen evolution cathodes than currently used materials, particularly under higher current densities. Electrolysis was conducted for 8 h, revealing improved stability of the coating deposited in the presence of SBS.