A robust & weak-nucleophilicity electrocatalyst with an inert response for chlorine ion oxidation in large-current seawater electrolysis

Abstract

Seawater splitting into hydrogen, a promising technology, is seriously limited by the durability and tolerance of electrocatalysts for chlorine ions in seawater at large current densities due to chloride oxidation and corrosion. Here, we present a robust and weak-nucleophilicity nickel–iron hydroxide electrocatalyst with excellent selectivity for oxygen evolution and an inert response for chlorine ion oxidation which are key and highly desired for efficient seawater electrolysis. Such a weak-nucleophilicity electrocatalyst can well match with strong-nucleophilicity OH− compared with the weak-nucleophilicity Cl−, resultantly, the oxidation of OH− in electrolyte can be more easily achieved relative to chlorine ion oxidation, confirmed by ethylenediaminetetraacetic acid disodium probing test. Further, no strongly corrosive hypochlorite is produced when the operating voltage reaches about 2.1 V vs. RHE, a potential that is far beyond the thermodynamic potential of chlorine ion oxidation. This concept and approach to reasonably designing weak-nucleophilicity electrocatalysts that can greatly avoid chlorine ion oxidation under alkaline seawater environments can push forward the seawater electrolysis technology and also accelerate the development of green hydrogen technique.