Probing the vertical profiles of potential in a thin layer of solution closed to electrode surface during localized corrosion of stainless steel

Based on a home-built integrated system of scanning reference electrode technique and scanning tunneling microscope (SRET/STM), a method for in situ measurement of vertical potential in the thin layer of solution closed to electrode surface during localized corrosion of stainless steel has been successfully established in this work. An obviously different vertical profile of potential over corrosion active sites and passive sites were firstly observed. The reason for this different was discussed taking into account the distribution of electric field and concentration of Fe3+/Fe2+ in a thin layer solution closed to electrode surface, due to the occurrence of localized corrosion.

► We develop a method for measuring vertical potential by combining SRET with STM.
► At corrosion active sites, the vertical potential profile exhibits a V-shape.
► At the passive area, the vertical potential profile decreases monotonously.
► The species distribution at corrosion active is different from at passive areas.