Elevating the photo-generated cathodic protection of corrosion product layers on electrogalvanized steel through nano-electrodeposition

The anticorrosion property of electrogalvanized steel mainly depends on the physical barrier of zinc's oxides or corrosion products to aggressive environments, which has reached a consensus for a long time. In this work, we demonstrated that the corrosion products (mainly ZnO) not only played a role of barrier layer in resisting seawater corrosion, but also provided an additional 30% of photo-generated cathodic protection for zinc coating under sunlight illumination according to the Stern-Geary resistance results. Then, we further elevated this sunlight-induced protection efficiency to approximately 100% by electrodeposition of nanocrystalline zinc, and analysed its improvement mechanism.