Facile design of graphene oxide-ZnO nanorod-based ternary nanocomposite as a superhydrophobic and corrosion-barrier coating

Abstract

We reported a facile design of ternary nanocomposites of polydimethylsiloxane (PDMS)/graphene oxide nanosheets decorated with ZnO nanorods (GO-ZnO NRs) as an outstanding superhydrophobic and anticorrosion coating material for steel substrates. GO-ZnO hybrid nanofiller was synthesized using a one-step chemical bath deposition, and the ternary nanocomposite was fabricated by solution casting. Hierarchical ZnO NRs were single crystals with 40–50 nm average width, < 1 μm average length, wurtzite structure, and exposed site in the [0001] crystal orientation. These NRs were decorated on < 2 nm-thick sheets of GO with nanoscale sizes, morphologies, and geometries. The PDMS/GO-ZnO ternary nanocomposite was dried through hydrosilation curing. The effects of different concentrations of GO-ZnO hybrid nanofiller dispersed in the PDMS resin on the barrier and anticorrosion properties were investigated. Surface features, including free energy, superhydrophobicity, chemical heterogeneity, and micro-nano roughness of the nanocomposite coatings were also studied. Electrochemical experiments including determination of Tafel polarization, electrochemical impedance spectra, and open circuit potential were conducted over carbon steel as the relatively immersed surface in a solution of 3.5% NaCl. Salt spray test was performed on the coated specimens for 500 h to study their corrosion protection. Results indicated that the silicone composite with 1 wt.% of GO-ZnO hybrid nanofillers exhibited excellent coating performance. This composite showed enhanced superhydrophobicity and roughness with water contact angle of 151° and corrosion protection. Hence, the designed PDMS/GO-ZnO ternary nanocomposite possesses outstanding superhydrophobic and anticorrosion features and could be used to design next-generation anticorrosive coatings.