Robust ZIF-67/AC/PDMS hybrid nanocomposite for superhydrophobic steel protection

Abstract

Abstract A superhydrophobic coating synthesized from Cobalt-based Zeolitic Imidazolate Framework (ZIF-67), Activated Carbon (AC), and Polydimethylsiloxane (PDMS) was successfully fabricated on a steel substrate. This coating was synthesized with concentration ratios S2 (1 wt% ZIF-67), S3 (3 wt% ZIF-67), S4 (5 wt% ZIF-67) and S5 (7 wt% ZIF-67), respectively. XRD and HR-TEM were applied to examine the crystalline structure and morphology of the synthesized nanocomposite. The results revealed S4 (5 wt% ZIF-67) composite as an optimized coating as it performed an exceptional surface wettability with a water contact angle (WCA) of 170° and superior chemical stability. Long-time laps of immersion tests in different pH range (3–11) nominated the S4 coating for retaining superhydrophobic integrity over 48 h, even placed in aggressive acidic or alkaline media. Electrochemical Impedance Spectroscopy (EIS) confirmed a robust corrosion protection performance of the S4 coating, as it recorded a high charge transfer resistance (R ct ) reaching 5 × 10 5 Ω⋅cm 2 . This enhanced performance is attributed to the modified roughness resulting from the ZIF-67/AC framework and the low surface energy of the PDMS matrix that stabilized a persistent Cassie-Baxter state. These results demonstrate the ZIF-67/AC/PDMS nanocomposite as a promising strategy for sustained corrosion protection of steel in severe industrial environments.