Potentiodynamic Chromium Deposition from Trivalent and Hexavalent Systems on Glassy Carbon Electrodes: Initial Stages and Mechanistic Insights

Abstract

Developing a functional Cr(III) electrolyte to replace carcinogenic and toxic Cr(VI) electroplating requires a deeper understanding of the deposition mechanisms. Hence, this study investigates and compares the growth of chromium on inert glassy carbon (GC) electrodes from low-concentration Cr(III) and Cr(VI) electrolytes, using a novel potentiodynamic deposition scheme. This allows the initial stages of deposition to be probed, which are crucial for determining the overall deposition mechanism. Scanning electron microscopy shows that, for both systems, micrometer-sized hexagonal chromium hydride crystals could be deposited on GC, thus serving to be the first reporting of such structures. In addition, by increasing the deposition time, the changes in a particle structure for both systems were tracked; therefore, possible areas of similarity as well as key differences could be identified, which, when addressed may provide a more viable, environmentally friendly trivalent electrolyte for chromium electroplating.

Electrodeposition of Cu onto Au(111) from Deep Eutectic Solvents: Molar Ratio of Salt and Hydrogen Bond Donor

“…The electrodeposition of these metals is impossible or at least very difficult from aqueous electrolytes and often, e. g . in the case of chromium, toxic and environmentally harmful deposition baths are used [9,10] . A promising and rather new class of electrolytes are deep eutectic solvents (DESs).…”

“…[5][6][7][8] The electrodeposition of these metals is impossible or at least very difficult from aqueous electrolytes and often, e. g. in the case of chromium, toxic and environmentally harmful deposition baths are used. [9,10] A promising and rather new class of electrolytes are deep eutectic solvents (DESs). DESs typically consist of a hydrogen bond donor in combination with an organic or inorganic salt, which is referred to as DES type III and DES type IV, respectively.…”

Low-frequency pulse plating for tailoring the optical appearance of chromium layers for decorative applications

“…The aim is to achieve a process-stable hue in the blue range of the color spectrum, as close as possible to the appearance of parts from hexavalent baths. The latter are still considered as benchmarks in decorative chromium plating [11].…”