Boosting Oxygen Evolution Reaction Performance on NiFe-Based Catalysts Through d-Orbital Hybridization.

ABSTRACT

Anion-exchange membrane water electrolyzers (AEMWEs) for green hydrogen production have received intensive attention due to their feasibility of using earth-abundant NiFe-based catalysts. By introducing a third metal into NiFe-based catalysts to construct asymmetrical M-NiFe units, the d-orbital and electronic structures can be adjusted, which is an important strategy to achieve sufficient oxygen evolution reaction (OER) performance in AEMWEs. Herein, the ternary NiFeM (M La, Mo) catalysts featured with distinct M-NiFe units and varying d-orbitals are reported in this work. Experimental and theoretical calculation results reveal that the doping of La leads to optimized hybridization between d orbital in NiFeM and 2p in oxygen, resulting in enhanced adsorption strength of oxygen intermediates, and reduced rate-determining step energy barrier, which is responsible for the enhanced OER performance. More critically, the obtained NiFeLa catalyst only requires 1.58 V to reach 1 A cm-2 in an anion exchange membrane electrolyzer and demonstrates excellent long-term stability of up to 600 h.