High Corrosion Resistance of NiFe-Layered Double Hydroxide Catalyst for Stable Seawater Electrolysis Promoted by Phosphate Intercalation

Abstract

Sustainable production of hydrogen from seawater electrolysis has attracted much attention in recent years. Considering that Cl^- might corrode metal substrate by crossing through the covered catalyst, the conventional Ni(II)Fe(III)-layered double hydroxide (NiFe-LDH) loaded on metal substrate, as a favorable oxygen evolution catalyst, cannot be directly used for seawater electrolysis. Herein, an anti-corrosion strategy of PO₄ ^3- intercalation in NiFe-LDH is proposed, in which the highly negatively charged PO₄ ^3- in the interlayers can prevent the Ni substrate from Cl^- corrosion by electrostatic repulsion. In order to verify the anti-corrosion effect, the two electrodes of the pristine NiFe-LDH and the PO₄ ^3- intercalated NiFe-LDH are evaluated in a solution with high Cl^- concentration. PO₄ ^3- can effectively hinder the migration of Cl^- between the interlayers of NiFe-LDH, thus the corrosion life of the PO₄ ^3- intercalated NiFe-LDH is more than 100 times longer than that of the pristine NiFe-LDH. The improvement of stability is attributed to the inhibition effect of Cl^- passing through the interlayers of NiFe-LDH, leading to the protection of Ni substrate. This work provides a design strategy for the catalysts loaded on the metal substrate, which has excellent Cl^- -corrosion resistance and can be widely used in hydrogen generation from seawater electrolysis.

Keywords: Cl - corrosion; hydrogen production; phosphate intercalated layered double hydroxide (LDH); seawater electrolysis.