The corrosion behaviour and hydrogen evolution reaction of Fe in non-aqueous formic acid

The corrosion of Fe in de-oxygenated non-aqueous formic acid was studied by the impedance method. It was confirmed that the cathodic reaction is a hydrogen evolution reaction (h.e.r.) and that formaldehyde is not formed. The rate-determining step (r.d.s.) of the h.e.r. is the formation of adsorbed hydrogen. The presence of adsorbed hydrogen was confirmed by the appearance of the low frequency capacitive arc obtained in the cathodic Tafel region of the impedance diagram. The inductive arc regarded as being due to the anodic dissolution of Fe was seen in the potential range between E_corr and cathodic Tafel region.