Sonication assisted superior anti-corrosion properties of cathodically deposited novel nickel-graphene oxide-zinc oxide coating

Abstract

This study details the sonication-assisted synthesis and characterization of a cathodically deposited novel nickel-graphene oxide -zinc oxide (Ni-GO-ZnO) composite coating achieved through electrodeposition and its comparison with anodically deposited GO. This coating was comprehensively characterized using Fourier-transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM) coupled with Energy-dispersive X-ray spectroscopy (EDAX). Subsequently, its corrosion resistance for MS1010 mild steel in 3.5 wt % (NaCl) was evaluated via weight loss, contact angle, electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization, and surface analysis techniques. These observations suggest that graphene oxide-zinc oxide (GO-ZnO) adsorbs nickel onto the MS surface effectively and reduces defects, which helps in blocking active corrosion sites. Tafel plots and EIS revealed that the Ni-GO-ZnO coating exhibited the lowest current density (39.95 µAcm²) and the highest charge transfer resistance (1211 Ωcm²). This was further validated by long-term immersion testing, where the Ni-GO-ZnO coating exhibited significantly less weight loss (1.33 mils/Y) compared to the deposited GO coating (2.2 mils/Y). The mechanism of formation of deposited GO and Ni-GO-ZnO coating on the metallic surface is proposed. The enhanced corrosion resistance of the Ni-GO-ZnO coating is attributed to its ability to 1) form a more compact metallic layer and 2) Minimize the active surface area vulnerable to corrosion attack. 3) Diminishes the presence of holes and cracks for corrosive ion ingress.4) Functionally impedes the ingress of chloride ions, primarily liable for steel degradation. The synergistic effect of the GO-ZnO constituents within the nickel matrix significantly enhances the long-term durability and integrity of the protective layer, a phenomenon hitherto unexplored. The empirical outcomes advocate for the advanced application of GO-ZnO-nickel coatings in safeguarding infrastructural materials against corrosive degradation.