Study of the electrodeposition of rhenium thin films by electrochemical quartz microbalance and X-ray photoelectron spectroscopy

Rhenium thin films were prepared by electrodeposition from an aqueous solution containing 0.1 M Na2SO4+H2SO4, pH 2 in presence of y mM HReO4. As substrates polycrystalline gold (y=0.75 mM HReO4) and monocrystalline n-Si(100) (y=40 mM HReO4) were used. The electrochemical growth of rhenium was studied by cyclic voltammetry and electrochemical quartz microbalance on gold electrodes. The results found in the potential region before the hydrogen evolution reaction (her) showed that ReO3, ReO2 and Re2O3 with different hydration grades can be formed. In the potential region where the her is occurring, either on gold or n-Si(100) the electrodeposition of metallic rhenium takes place. On both substrates, rhenium films were formed by electrolysis at constant potential and X-ray photoelectron spectroscopy technique was used to characterise these deposits. It was concluded that the electrodeposited films were of metallic rhenium and only the uppermost atomic layer contained rhenium oxide species.