Indigo carmine dye enables durable alkaline seawater oxidation over NiFe LDH

Abstract

Seawater electrolysis is highly promising for green hydrogen production, while the anode suffers from inferior stability due to chlorine corrosion. Here, indigo carmine (IC) dye is proposed as a dianionic modifier for NiFe layered double hydroxide nanoarrays on nickel foam to create an anionic passivation layer. Fourier-transform infrared spectroscopy analysis confirms the introduction of IC molecules. As an anti-chlorine corrosion catalyst for alkaline seawater oxidation (ASO), the resulting IC@NiFe LDH/NF demands an overpotential of 367 mV to deliver an industrial-level current density of 1000 mA cm⁻², much lower than that for its unmodified counterpart (412 mV). Impressively, when operated under such high current density, IC modification prolongs the operating lifespan from 110 h to 1200 h with negligible performance decay and almost no detectable active chlorine in the post-electrolysis electrolyte. In situ Raman spectroscopy analysis further verifies that IC modification accelerates the surface reconstruction of NiFe LDH, promoting the formation of catalytically active Ni^III–O species during the ASO process.