Sustainable superhydrophobic coating based on in-situ electrodeposited Ni-Al layered double hydroxide for enhanced corrosion protection of steel

The development of durable superhydrophobic coatings for corrosion protection remains a significant challenge due to the weak mechanical and chemical stability of most synthetic surfaces. This work presents a highly stable, eco-friendly superhydrophobic coating fabricated on steel via a facile two-step process. Ni-Al layered double hydroxide (LDH) with a unique Micro-nano morphology was first grown in-situ by a one-pot electrodeposition method, creating a rough hierarchical structure. This was subsequently functionalized with stearic acid, a green low-surface-energy material, to achieve superhydrophobicity. Systematic optimization of the electrodeposition parameters revealed that a 15-minute deposition at 40 mA yielded the optimum coating, which exhibited a water contact angle of 161° and a sliding angle of 3°. Extensive characterization, including SEM, AFM, XRD, and XPS, confirmed the successful formation and structure of the coating. Electrochemical tests in a solution of 0.5 M NaCl displayed that the optimized coating significantly enhanced the corrosion resistance of steel, achieving a protection efficiency of 96.5%. Crucially, the coating exhibited exceptional durability, maintaining its superhydrophobicity after 1100 mm of linear abrasion and demonstrating remarkable chemical stability against corrosive media across a wide pH range from 1 to 13. This study not only provides a novel method for constructing environmentally stable LDH-based coatings but also highlights their significant potential for real-world anti-corrosion applications in demanding environments.