Multimetallic layered double hydroxides as efficient and durable oxygen evolution catalysts for anion exchange membrane water electrolysis at high current densities

Abstract

The development of efficient and durable electrocatalysts for the oxygen evolution reaction (OER) is critical for advancing anion exchange membrane water electrolysis (AEMWE) technology for sustainable hydrogen production. Herein, we report the synthesis of multimetallic NiCrFeMo layered double hydroxides (LDHs) via a facile microwave-assisted hydrothermal approach, engineered as high-performance OER catalysts for AEMWE operating at industrially relevant current densities. Advanced X-ray absorption spectroscopy (XAS) studies demonstrate that the interplay of Ni, Cr, Fe, and Mo tailors the electronic structure and coordination environment. Consequently, the NiCrFeMo LDHs exhibit remarkable OER performance, achieving overpotentials of 236 and 387 mV at 10 and 500 mA cm⁻², respectively, in 1.0 M KOH, as well as outstanding durability at 500 mA cm⁻² for 1000 hours with negligible degradation. In situ differential electrochemical mass spectroscopy (DEMS) and density functional theory (DFT) analyses reveal that the OER taking place on NiCrFeMo LDHs follows the adsorbate evolution mechanism, with minimal lattice oxygen involvement, contributing to the catalyst's longevity. When integrated into a prototype AEM electrolyzer cell as the anode catalyst, the cell demonstrates a current density of 1 A cm⁻² at a relatively low voltage of 1.87 V and operates at 0.5 A cm⁻² for 100 hours without decay, highlighting the potential of NiCrFeMo LDHs for practical applications. This work elucidates the synergistic effects of multimetallic compositions in LDHs, offering a strategy for designing cost-effective, high-efficiency OER catalysts to support green hydrogen production on scale.