Ni-Al layered double hydroxide films offering corrosion protection under dark or illuminated conditions

Layered double hydroxide (LDH) films have been used to protect metal substrates because of their superior barrier performance and capability of capturing corrosive anions (such as Cl − ) by exchange with interlayer anions. In this preliminary work, we determined that some photoactive LDHs (such as NiAl-LDH) can also provide cathodic protection to metals under light illumination, stemming from the light-generated electrons of semiconducting LDHs, if the energy level of the conduction band of LDHs is higher than the Fermi level of the metal. The current experimental results prove that the corrosion resistance of stainless steel is enhanced by the attached NiAl-LDH films in the dark and is further increased under light illumination due to photogenerated cathodic protection.