Corrosion-Induced Anticorrosion on Steel.

Steel corrosion, an inherent degradation of critical infrastructure, remains a pervasive global challenge. Here we report a serendipitous discovery of a corrosion-induced self-passivation strategy for steel in aqueous mixtures of polymaleic acid (PMA), phosphoric acid, and zinc phosphate (PMAPAZ) driven by the spontaneous formation of dense γ-Fe2O3/PMA nanohybrid coating. This corrosion-induced coating effectively inhibits steel corrosion under aggressive conditions, including high acidity (pH 1.5), high chloride (5 wt %), and elevated temperature (120 °C), achieving an ultraslow corrosion rate (<2 μm·year-1) in 3.5 wt % NaCl under ambient conditions. This superior anticorrosion performance can also be accomplished by directly applying PMAPAZ solutions or solution-infused dressings to a rusty steel surface without prior surface preparation, enabling simple, on-site repair and documented corrosion protection during natural outdoor atmospheric exposure for over 1 year. Our findings offer a regenerative and practical solution to a long-standing challenge in the steel industry, turning the inevitability of corrosion into a single-step opportunity for durable self-passivation.