In situ electrochemical atomic force microscopy with atomic resolution of Fe(110) in sodium sulfate aqueous solution

Abstract

In situ electrochemical atomic force microscopy (EC-AFM) was used to investigate a bare Fe(110) and an anodically formed oxide on Fe(110) in 0.05 M Na2SO4 aqueous solution under potential control. An unreconstructed Fe(110)-(1×1) structure was observed at -1.9 V in 0.05 M Na2SO4 aqueous solution by keeping the potential in hydrogen evolution region for 10 min. This is the first In situ EC-AFM image with atomic resolution of unpassivated iron electrodes under aqueous solution. We also observed Fe(OH)2(0001)-(1×1) structure of an anodic oxide layer grown on Fe(110) single crystal at -1.2 V in 0.05 M Na2SO4 aqueous solution. From these EC-AFM investigation, we have found an epitaxial relationship of Fe(OH)2(0001)[21̄1̄0]∥Fe(110)[11̄0] between the anodic oxide layer and Fe(110) substrate.