A highly active NiCe(Fe)OxHy electrocatalyst for the oxygen evolution reaction with ultralow Fe leaching

Abstract

Nickel–iron hydroxide (NiFeO_xH_y) is a promising electrocatalyst for alkaline water oxidation but suffers from phase segregation and Fe dissolution under OER conditions. Here, we integrate cerium oxide (CeO_x) into NiFe hydroxide, forming a NiCe(Fe)O_xH_y electrocatalyst. Detailed characterization reveals that the introduction of Ce triggers a phase transition of Fe species from crystalline Fe₂NiOOH to dispersed states in Ni(OH)₂–CeO₂ domains. The dispersed Fe–O species modulate charge distribution across the Ni(Fe)(OH)₂–Ce(Fe)O₂ interface, generating two types of Ni–O sites, instead of being directly involved in the OER cycle. This improves Fe's stability and suppresses Fe leaching. Mechanistic investigations confirm that interfacial dual Ni–O sites synergistically participate in the oxygen evolution reaction (OER), especially under low applied potentials. The optimized NiCe(Fe)O_xH_y catalyst exhibits a mentionable performance with a low overpotential of only 303 mV at 500 mA cm⁻², 98 mV lower than that of NiFeO_xH_y. Meanwhile, Fe leaching from the optimized NiCe(Fe)O_xH_y electrode is suppressed over 98% under industrial conditions (80 °C, 30 wt%), highlighting its superior structural stability.