Ga-Induced Electron Pump Optimization of Fe active sites in NiFe-LDHs for Efficient Alkaline Water Electrooxidation

Abstract

The development of efficient and stable electrocatalysts for the alkaline oxygen evolution reaction (OER) is crucial for large-scale industrial application in producing green hydrogen. Herein, we propose a targeted electronic modulation strategy to enhance the OER performance of NiFe layered double hydroxides (LDHs) via Ga³⁺ doping. Preliminary theoretical analyses indicate that Ga³⁺, serving as a strong Lewis acid center with high electron-withdrawing ability, effectively optimizes the electronic structure of adjacent Fe active sites through indirect orbital interactions. As a result, the synthesized NiFeGa-LDHs anode exhibits a low overpotential of only 275 mV at 50 mA cm⁻² in 1 M KOH and, notably, maintains stable operation for over 100 hours at an industrial-level current density of 1 A cm⁻² in an anion exchange membrane (AEM) electrolyzer test (configured as NiFeGa-LDHs//Pt-C), demonstrating​overall performance superior to the commercial RuO₂//Pt-C benchmark. Through a combination of theoretical and experimental characterizations, we demonstrate that Ga³⁺ acts as an “electron pump” to effectively tune and stabilize the Fe active sites. Operando spectroscopic analyses further confirm that this electronic modulation drives an earlier and more extensive electrochemical reconstruction of the catalyst into the active γ-NiFeOOH phase, which is identified as the key structural origin of the activity enhancement. This work pioneers a targeted electronic structure engineering tactic via strong Lewis acid doping, providing a transformative pathway for designing advanced electrocatalysts beyond the OER.