A sequential dual-passivation strategy for designing stainless steel used above water oxidation

Stainless steel is critical material used in a wide variety of industries. Unfortunately, current development of stainless steel has reached a stagnant stage due to the fundamental limitation of the conventional Cr-based single-passivation mechanism. Here, we show that, by using a sequential dual-passivation mechanism, substantially enhanced anti-corrosion properties can be achieved in Mn-contained stainless steel, with a high breakdown potential of ∼1700 mV (saturated calomel electrode, SCE) in a 3.5 wt% NaCl solution. Specifically, the conventional Cr-based and counter-intuitive Mn-based passivation is sequentially activated during potentiodynamic polarization. The Cr-based passive layer prevents corrosion at low potentials below ∼720 mV(SCE), while the Mn-based passive layer resists corrosion at high potentials up to ∼1700 mV(SCE). The present “sequential dual-passivation” strategy enlarges the passive region of stainless steel to high potentials above water oxidation, enabling them as potential anodic materials for green hydrogen production via water electrolysis.