Anticorrosion and antibiofouling performance of in-situ prepared layered double hydroxide coating modified by sodium pyrithione on aluminum alloy 7075

• In-situ growth layered double hydroxide (LDH) coating modified by sodium pyrithione (SPT) is prepared. • Co-Al LDHs-SPT coating possesses a high anticorrosion effect. • Co-Al LDHs-SPT coating can effectively inhibit the adhesion of Pseudomonas aeruginosa and spirulina . • The existing forms of SPT in LDH include anion-layer, physisorption, and chemisorption. The anticorrosion and antibiofouling of marine engineering equipments have strong demands, especially for antibiofouling. In this work, an in-situ growth layered double hydroxide (LDH) coating on aluminum alloys (AA) 7075 was prepared and then modified by sodium pyrithione (SPT) to increase the anticorrosion and antibiofouling performance. Results indicated that CoAl-LDHs and CoAl-LDHs-SPT coatings had been successfully prepared according to TEM, XRD, XPS, Raman spectra, and SEM analysis results. The (0 1 2) plane of LDHs with a interplanar spacing of 0.26 nm was recognized from TEM images. The content of SPT in CoAl-LDHs-SPT is 38.79 wt.%. Electrochemical impedance spectroscopy (EIS) and polarization curvies demonstrate that the corrosion resistance of AA 7075 was largely improved in the presence of CoAl-LDHs and CoAl-LDHs-SPT coatings while the anticorrosion performance of CoAl-LDHs-SPT coating was better. The corrosion resistance of Co-Al LDHs-SPT coating increased by about two orders of magnitude compared with the bare AA 7075. The surface analysis results show that only a few Pseudomonas aeruginosa and Spirulina cells attached to the CoAl-LDHs coating surface, and no biofouling cells were observed for the CoAl-LDHs-SPT coating. Co-Al LDHs-SPT coating possessed the best anticorrosion and antibiofouling properties due to the presence of SPT compared with the CoAl-LDHs coating.