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

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. Safe and sound: Potentiodynamic deposition of hexagonal chromium hydride crystals on glassy carbon enables the initial stages of deposition from trivalent and hexavalent chromium electrolytes to be probed. The results highlight both similarities and differences, which, supported by literature, provide key mechanistic insights that should be considered when developing an environmentally safe trivalent substitute for the chromium electroplating industry.