Use of Raman Spectroscopy and Rotating Split Ring Disk Electrode for Identification of Surface Layers on Iron in 1M   NaOH

Abstract

In situ Raman spectroscopy and rotating split-ring disk electrode were used to identify products formed on iron in 1M NaOH at 22~ at various peaks of cyclic voltammograms. The peak at the most active potential of the cathodic reverse sweep has been ascribed to the reduction of Fe304 to Fe 2+ species: this peak suggested that Fe304 started to form at the first peak of anodic sweep and that it built up at nobler potentials. The Raman spectroscopy has revealed the formation of Fe304 in the wide range of potentials, of ~-FeOOH and/or Fe304 at peak III of anodic sweep, and of ~]-Fe203 after prolonged polarization at a potential of 0.27V (SCE). Rapid cycling or long exposure resulted in the formation of Fe304 and a-FeOOH. It is suggested that the passivating film on iron in 1M NaOH is composed of an inner Fe304 layer and of an outer layer containing other products.The electrochemistry and corrosion of iron and carbon steel in hydroxide solutions have been studied by many authors (1-20). Technological importance of the iron/ hydroxide system is associated with alkaline batteries, with hydrolysis of water, and with corrosion in hot alkalies. Extensive studies have been devoted particularly to the passivation and composition of passive films.Hydrolysis of soluble corrosion products on iron in alkalies leads to the formation of Fe(OH)2 (21). Eventually there are formed Fe304 (22), ~-Fe203 (23, 24), ~-FeOOH (21, 23) and other oxyhydroxides (25). ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 192.236.36.29 Downloaded on 2015-04-11 to IP

Chloride in cement

“…Hugot-Le Goff et al (1990) identified the products formed on iron in 1 M sodium hydroxide using in situ Raman spectroscopy and a rotating split ring disc electrode. A rotating ring disc electrode consists of a double working electrode which, by rotation, induces a flux of analyte to the electrode.…”

Multi-scale investigation of the formation and breakdown of passive films on carbon steel rebar in concrete

“…In-situ Raman spectroscopy and rotating split-ring disk electrode were used by Hugot-Le Goff et al (1990) to identify iron oxides that form on the surface of iron in 1 M NaOH. Fe304 started to form at the first peak of anodic polarization sweep and grew continuously at more noble potentials.…”

Monitoring Corrosion Using Vibrational Spectroscopic Techniques

“…Most of the oxide films studied were either formed by anodic polarization [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] or by exposing the metals to hydrothermal environments. A series of work has focused on in situ Raman spectroscopic identification of oxide films grown on various metal surfaces, including Fe, Ni, Co, Ag, Ti, Pb, and stainless steel.…”

“…During this process, the formation, transformation (if any), and dissolution of the oxide films could be followed using in situ Raman spectroscopy. [11][12][13]15 An outer layer consisting of goethite (α-FeOOH) or lepidocrocite (γ-FeOOH) was also detected. 3 On Cu in 0.1 M NaOH, Cu 2 O was detected for potentials from 50 to about 500 mV during anodic sweeps, but was converted to Cu(OH) 2 at more anodic potentials (>637 mV), as evidenced by the appearance of the band at ~488 cm −1 .…”