Comprehensive anti-corrosion study of electrodeposited graphene oxide-alumina composite with nickel matrix in NaCl solution

Abstract

In this work, a matrix of nickel composite coating is embedded with graphene oxide and alumina. This work developed a matrix of nickel composite coating embedded with graphene oxide and alumina (GO-Al2O3) at various concentrations using an electrodeposition process. Fourier transforms infrared spectroscopy (FTIR) and Energy-dispersive X-ray spectroscopy (EDAX) confirmed further incorporation of GO and GO-Al2O3 within nickel coating. The calculated crystal size of the nickel coating was 19.46 nm; however, it reduced to 11.58 nm in the Ni-GO-Al2O3 (1.5 g/L) coating. The surface morphology of Ni-GO-Al2O3 coating using Field emission Scanning electron microscopy (FE-SEM) showed fine grain size; however, nickel had cubic-shaped crystals and was significantly larger. Contact angle measurements reveal the hydrophobic characteristic of the Ni-GO-Al2O3 coating, which was 110.8° compared to nickel (71.4°). Tafel and electrochemical impedance showed maximum polarization resistance for Ni-GO-Al2O3 (1.5 g/L) coating. The developed Ni-GO-Al2O3 coating was put through short, long-term immersion tests and showed less weight loss than Ni and Ni-GO coating. pH change was the least for Ni-GO-Al2O3 coating due to its compact shape, which prevented the transport of corrosion-causing ions to the metal and consequently reduced metal oxidation. Ni-GO-Al2O3 coating shows the least blue spot, indicating negligible rupture after immersion. Atomic force microscopy study revealed that Ni-GO-Al2O3 has a smoother surface, which did not significantly change even after immersion. Nickel coating showed cracks, producing high corrosion products and more pits, showing its inability for long-term inhibition; however, Ni-GO-Al2O3 coating with the least cracks and pits showed negligible corrosion products on its surface even after one month of exposure. Fe and O are higher in Ni and Ni-GO after immersion and least in Ni-GO-Al2O3, making it more protective. Compared to pure Ni coatings, the composite coating electrode containing 1.5 g/L of GO-Al2O3 had the best corrosion resistance due to the abovementioned characteristics.