Hydrogen Mediated Electrodeposition: A Case of ReRu Alloys

Electrochemical deposition of rhenium-ruthenium (Re-Ru) was investigated to probe the impacts of adsorbed hydrogen on the co-deposition of binary alloy. Cyclic voltammetry, chronoamperometry, and X-ray fluorescence were utilized to characterize the electrochemical system and to determine the deposition partial current densities of each element. A thickness dependent deposition rate of rhenium was observed and was further studied in conjunction with the hydrogen evolution reaction on different substrates. The results are discussed in a framework of multi-step reduction mechanism involving the adsorbed hydrogen intermediate species. While the co-deposition of Ru with Re modifies the Cu electrode surface, promoting the Re deposition rate at the initial stage, the subsequent deposition on the alloy itself reveals a mutual inhibitive interaction between the two. Preliminary studies on Re co-deposition with Cd and Zn further confirm the effect of adsorbed hydrogen intermediate, where the much weaker affinity on these metals nearly disables the Re deposition.