Corrosion Inhibition Mechanism of Typical Inorganic Inhibitors on Stainless Steel in a Simulated Electrolytic Seawater Environment

• • V2O5 at 0.05 mol/L achieved inhibition efficiencies of 79.90% for 316L SS and 89.58% for 2205 DSS in 6.0 mol/L NaOH + 2.0 mol/L NaCl at 90 °C, demonstrating its superior performance in extreme alkaline chloride environments; this translates to a potential 5–10× extension of component service life in industrial electrolyzers, reducing maintenance downtime and replacement costs. • • Na3PO4 delivered 83.33% inhibition efficiency for 2205 DSS, positioning it as a viable secondary option; however, its performance on 316L SS was lower, indicating alloy-specific compatibility that must be considered in material selection for electrolyzer components. • • EIS data for 316L SS with 0.05 mol/L V2O5 showed Rct = 29,770 Ω·cm² and Rf = 923.50 Ω·cm², with CPEf parameter Y0 at its lowest and n = 1, signifying a dense, uniform film with minimal dispersion; this directly correlates with reduced charge-transfer kinetics and a more effective barrier against corrosive species. • • XPS analysis detected V4+ and V5+ states in the V2O5 system and PO4³− in the Na3PO4 system, confirming the formation of a vanadium/phosphate composite film that modifies the Fe 2p binding energy and suppresses metal dissolution; this mechanistic insight enables the design of tailored inhibitor formulations for specific stainless steel grades.