Thin Composite Films of Mussel Adhesive Proteins and Ceria Nanoparticles on Carbon Steel for Corrosion Protection

Abstract

Thin composite films of the mussel adhesive proteins (Mefp-1) and ceria nanoparticles were deposited on substrate surfaces by alternating immersions. The film formation was studied by quartz crystal microbalance with dissipation (QCM-D) monitoring. Both the changes in frequency and dissipation recorded by QCM-D demonstrate buildup of a composite film of Mefp-1 and nanoceria. Micro-and nanostructure and composition of the film on carbon steel were characterized by optical and atomic force microscopy (AFM), electron probe micro analyzer (EPMA) and confocal Raman microspectroscopy (CRM). Optical and EPMA observations of the film show micron-sized aggregates and AFM imaging of the compact and smooth areas reveal the nanostructure. EPMA elemental mapping indicates that the micron-sized aggregates are rich in ceria and Mefp-1, whereas CRM analysis shows the presence of Mefp-1-Fe complexes in the film. Corrosion protection of the composite film on carbon steel was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements in NaCl solution, and compared with Mefp-1 added in the solution as an inhibitor. The measurements show that the composite film provides a higher corrosion resistance compared with Mefp-1 added as inhibitor. The corrosion resistance increases with exposure time and approaches a high level. Corrosion inhibitors are widely used to control corrosion of metallic materials that causes huge economic cost to our society, and even catastrophes due to unexpected failure of metallic constructions and devices. In the past decade, extensive efforts have been devoted to developing new "green" corrosion inhibitors to replace traditional ones that are harmful to human health and ecological systems.1 Filmforming inhibitors based on organic substances that are more "green" for human and environment have attracted considerable attention in recent years. For example, a mussel adhesive protein (MAP), derived from marine mussel Mytilus edulis, has shown a certain inhibition effect on stainless steel.2 In our previous study, Mefp-1, the type of MAP that has been most studied, was shown to exhibit interesting inhibiting properties on carbon steel in NaCl solutions. However, the inhibition efficiency of Mefp-1 is limited since the adsorbed film is not sufficiently compact, and this is particularly a problem for the initial period during which Mefp-1 does not give a significant inhibition effect. 3The adhesive and cohesive properties of MAP are generally attributed to the high content of di-hydroxyphenylalanine (DOPA), 4 which has been reported to form complexes with metal ions 5,6 and metal oxides. Waite et al. have concluded that the DOPA moiety in the proteins serves two important roles in MAP adhesion to many surfacesthe formation of interfacial complexes promoting chemisorption and cross-links. 8,9 In another study of adsorption and corrosion protection of polydopamine based surface films on aluminum alloys, it was concluded that these self-assembled surface films can provide a c...

In situ confocal Raman micro-spectroscopy and electrochemical studies of mussel adhesive protein and ceria composite film on carbon steel in salt solutions

“…2a, shows that the Mefp-1 related spectrum is almost identical to the one obtained in air [24]. This indicates very limited corrosion product formation within this short exposure period.…”

“…In this regard, it was reported that ceria nanoparticles are not cytotoxic but instead protect cells from oxidation insult [23]. In our previous study [24], a thin composite film of Mefp-1 and ceria nanoparticles was shown to exhibit significant corrosion protection for carbon steel in NaCl containing phosphoric acid. A combination of both ex situ and in situ techniques has been used to investigate the film formation, structure and corrosion inhibition performance.…”

“…The morphology, composition, and micro-and nano-structure of the Mefp-1/ceria composite film deposited on a carbon steel surface have previously been characterized ex situ by using optical microscopy, SEM and AFM, as well as WDS/EDS and CRM analysis [24]. However, identification of the ceria and iron oxide compounds in the thin composite film was not possible due to limitations of the surface sensitivity of the applied techniques.…”

“…However, identification of the ceria and iron oxide compounds in the thin composite film was not possible due to limitations of the surface sensitivity of the applied techniques. The XPS technique, with a measuring depth of several nm, enables the analysis of the outmost surface layer, close to the thickness of the composite film ≈10 nm [24]. In this case, the detected XPS signal mostly originates from the Mefp-1/ceria composite film, whereas the surface oxide formed on the steel surface below the composite film only provides weak signals.…”

Investigations of Mussel Adhesive Proteins as Flash Rust Inhibitors

“…7 Previous investigations have indicated that DOPA-containing proteins are capable of inhibiting corrosion to various degrees on some metals. 1,[8][9][10][11][12][13] In addition to this, DOPA can participate in crosslinking reactions as a result of chemical or enzymatic oxidation. When oxidized, DOPA forms a quinone-intermediate, which can in turn react further with catechol groups or nucleophiles present elsewhere in the protein to form a crosslinked protein.…”