ABSTRACT Sulfite‐based gold electrodepositions are explored as a cyanide‐free route for protective and conductive coatings in proton exchange membrane (PEM) water electrolysis. Multilayered Au/Ni/Cu coatings exhibit dense microstructures, well‐defined interfaces, and typical Au reflections of the fcc crystal system. Contact resistance remains low across the relevant compaction range, reaching 9.39 mΩ cm 2 at 150 N cm −2 , consistent with the performance of commercial cyanide‐derived coatings, meeting the international standards. Corrosion testing showed similar corrosion potentials and currents for both systems, whereas chronoamperometry revealed an under 2 mA current at 2 V and a more stable course for the sulfite‐based coating. In situ cell measurements under representative PEMWE operating conditions with polarization up to 2 A cm −2 reached cell potentials of under 1.9 V and no indication of significant mass‐transport limitations. Operation exceeding 160 h showed overlapping polarization curves before and after chronoamperometry testing and a degradation rate 11.8 µV h −1 , indicating stable electrochemical behavior. Overall, the sulfite‐complexed deposition approach delivers physical characteristics and acidic electrochemical behavior consistent with established industrial gold coatings while eliminating cyanide from the process.
Kazamer et al. (Wed,) studied this question.