High-Interface Alkalinity Induced by Intercalated Squaric Acid Anions for 700 Hours of Oxygen Evolution at 3 A cm−2

The corrosive acidic interfacial microenvironment caused by rapid multistep deprotonation of the alkaline oxygen evolution reaction (OER) in industrial high-current water electrolysis is one of the key problems limiting activity and stability. Some functional anions derived from electrocatalysis exhibit special functionalities in modulating the catalytic interface microenvironment, but this matter has not received adequate attention in academic discussions. The coordinated squaric acid molecule is revealed to undergo a dissolve-reintercalation process in the alkaline OER, leading to its eventual stabilization within the Fe-doped NiOOH interlayer in the form of squaric acid anions (Sq ²⁻ ) (NiFe-SQ/NF-R). This intercalated Sq ²⁻ stabilizes OH ⁻ through multiple hydrogen bond interactions, which is conducive to maintaining high catalytic interface alkalinity. Hence, the interfacial acidification of the prepared NiFe-SQ/NF-R in the alkaline OER process is significantly inhibited, resulting in a tenfold increase in its catalytic durability (from 65 to 700 hours) when exposed to a high current density of 3.0 A cm ^− 2 , as opposed to traditional NiFe-LDH/NF-R materials. This derived functional anion guarantees the enduring performance of the NiFe-derived electrocatalyst under high current densities by controlling the interfacial alkalinity.