Dual resistance to chloride ion effects of PBA−derived self–supporting FeNi sulfide for high efficiency seawater oxidation

Abstract

Electrolysis of seawater is a promising approach to address freshwater scarcity and indirectly mitigate the energy crisis. In this context, the oxygen evolution reaction (OER) plays a crucial role as one of the half−reactions in water electrolysis. However, the development of cost−effective non−precious metal catalysts for OER remains a challenging issue. In this study, we present a facile method for synthesizing Prussian blue sulfides supported on nickel foam (NF) at ambient temperature. The resulting S−FeNi@NF catalyst demonstrates remarkable electrocatalytic performance with an overpotential of only 330 mV at a current density of 100 mA cm⁻² in simulated seawater. Notably, the catalyst exhibits excellent corrosion resistance and electrochemical stability, maintaining its effectiveness for over 120 h following vulcanization. Furthermore, we assessed the catalysts for their resistance to chloride ion corrosion in natural seawater and observed no significant signs of etching for more than 30 days. This outstanding stability of the S−FeNi@NF material can be attributed to its dual protective mechanisms against chloride ions, which encompass both corrosion resistance and the repulsion of chloride ions during electrochemical processes. Our findings offer a fresh perspective on catalyst design, particularly in the context of shielding against chloride−induced degradation in direct seawater electrolysis.