High-Performance Oxygen Evolution Anode from Stainless Steel via Controlled Surface Oxidation and Cr Removal

Improving the water oxidation performance of abundantly available materials, such as stainless steel (SS), with notable intrinsic electrocatalytic oxygen evolution reaction (OER) activity due to the presence of Ni and Fe is highly anticipated in water splitting. A new method for promoting the corrosion of stainless steel (304) was found which assisted the uniform formation of oxygen evolution reaction (OER) enhancing NiO incorporated Fe₂O₃ nanocrystals with the simultaneous reduction in the surface distribution of OER inactive Cr. An equimolar combination of KOH and hypochlorite was used as the corroding agent at 180 °C. The effect of corrosion time on the OER activity was studied and found that better water oxidation performance was observed when the corrosion time was 12 h (SS-12). The SS-12 showed an abnormal enhancement in OER activity compared to the untreated SS and other optimized versions of the same by requiring very low overpotentials of 260, 302, and 340 mV at the current densities of 10, 100, and 500 mA cm^-2 along with a very low Tafel slope in the range of 35.6 to 43.5 mV dec^-1. These numbers have certainly shown the high-performance electrocatalytic water oxidizing ability of SS-12. The comparative study revealed that the state-of-the-art IrO₂ had failed to compete with our performance improved catalytic water oxidation anode "the SS-12". This fruitful finding indicates that the SS-12 has the potential to be an alternate anode material to precious IrO₂/RuO₂ for alkaline water electrolyzers in future.