Super-Anticorrosive Materials Based on Bifunctionalized Reduced Graphene Oxide

Abstract

The design of new materials with two or more functional groups must be strongly considered to achieve multifunctional coatings with outstanding properties such as active−passive protection against corrosion, low-friction, antifouling, and sensing, among others. In this sense, nanocomposites based on solvent-free epoxy resin/bifunctionalized reduced graphene oxide layers with NH 2 and NH 3 + groups (ER/BFRGO) with super-anticorrosive properties are for the first time reported here. The amine groups (−NH 2 ) act as cross-linker agents, which react with epoxy terminal groups from resin, thus closing the gap between the BFRGO layers and the polymeric matrix. Meanwhile, the ammonium ions (−NH 3 + ) are effective trapping agents of negatively charged atoms or molecules (e.g., Cl − ). This novel combination enables us to obtain nanocomposite coatings with passive−active protection against corrosion. ER/BFRGO deposited onto A36 mild steel exhibited a remarkably enhanced barrier against corrosion into a saline medium (1 M NaCl; 58.4 g/L), wherein the corrosion current density (i corr ) was diminished 6 orders of magnitude (i corr = 5.12 × 10 −12 A/ cm 2 ), with respect to A36 mild steel coated only with ER (i corr = 2.34 × 10 −6 A/cm 2 ). Also, the highest polarization resistance R p = 6.04 × 10 7 Ω/cm 2 was obtained, which represents the lowest corrosion rate and corresponds to 3 orders of magnitude higher than A36 mild steel coated with ER (R p = 1.43 × 10 4 Ω/cm 2 ). The strategy of bifunctionalization proposed herein to obtain bifunctionalized reduced GO with NH 2 and NH 3 + groups has not been disclosed in the literature before; in consequence, this work opens a new pathway toward the design of smart materials based on multifunctional nanomaterials.

A Simple and Expeditious Route to Phosphate-Functionalized, Water-Processable Graphene for Capacitive Energy Storage

“…It can be observed that the peak for the different PFG-acid or PFG-salt samples is located between 260 and 270 nm, as shown in Figure S1a,b (Supporting Information). This absorption peak corresponds to π → π* transitions from electronically conjugated domains in carbon materials, 16,21 and its position at 260−270 nm is associated to graphitic/graphene materials with low to moderate oxidation levels. 37 These results are thus consistent with the O/C ratios obtained by XPS for the present graphene samples (Table 1).…”

“…It is worth noting that anodic exfoliation is considered a greener and environmentally respectful process, due to the use of water as the electrolyte which leads to a high yield of exfoliated layers; nevertheless, it can produce oxygen-centered radicals from the anodic oxidation of water that attack the exfoliated layers. 16 On the other hand, the chemical surface modification of graphene prevents the restacking of the exfoliated layers and can potentially improve their electrochemical performance, 21,22 since the new functional groups promote localized effects on the graphene layer, thus enhancing their physicochemical properties. In particular, several heteroatoms, including N, P, S, and B, have been incorporated into the graphene lattice 23−26 (doping), and nitrogen-, sulfur-, and phosphorus-based functional groups (i.e., -NO x , -SO x , and -PO x ) have been used to chemically functionalize the graphene nanosheets.…”

“…On the other hand, the chemical surface modification of graphene prevents the restacking of the exfoliated layers and can potentially improve their electrochemical performance, , since the new functional groups promote localized effects on the graphene layer, thus enhancing their physicochemical properties. In particular, several heteroatoms, including N, P, S, and B, have been incorporated into the graphene lattice − (doping), and nitrogen-, sulfur-, and phosphorus-based functional groups (i.e., -NO x , -SO x , and -PO x ) have been used to chemically functionalize the graphene nanosheets. ,,, Among them, phosphorus-based functional groups are highly desirable for electrochemical energy-storage devices since they possess an excellent electron-donating ability improving the band gap of the functionalized layers.…”

Reduced Graphene Oxide Nanoplatelets Functionalized with Nonpolar Aliphatic Groups for High-Performance Coatings against Corrosion

“…The polarization resistance for Propyl-rGO showed stable values of 3.7 × 10 8 Ω/cm 2 (Table ), 4 orders of magnitude higher than the values obtained for the neat epoxy. It is worth highlighting that, according to the results obtained from PCCs, the use of an aliphatic-functionalized GO allows competitive nanocomposite coatings in comparison with the coatings reported in the literature using graphene, GO, rGO, polar functionalized GO, ,− polar functionalized rGO, among others, − as shown in Figure c. Nevertheless, when the aliphatic-functionalized GO was structurally restored (elimination of the oxidized carbon species), a high-performance nanocomposite material against corrosion for A36SS in a saline medium was obtained.…”

On the Effect of Ultralow Loading of Microwave-Assisted Bifunctionalized Graphene Oxide in Stereolithographic 3D-Printed Nanocomposites

“…Surface functionalization of graphene oxide (GO) is one of the most facile ways to ensure homogeneous dispersions of GO layers in polymeric matrices. − The suitable choice of the functional groups prevents the reagglomeration of the GO layers, promoting excellent compatibility with the polymeric matrix, thus obtaining polymer nanocomposites with enhanced macroscopic properties. − In particular, many previous studies have reported the monofunctionalization of GO using silane coupling agents (SCAs), as well as their incorporation into the polymeric matrices to improve the thermal, , mechanical, − electronic, tribological, and anticorrosion ,, properties, among others, of the resulting nanocomposites. In most of these reports, monofunctionalized GO with one type of SCAs and degree of functionalization has been used.…”