Trojan strategy assisted phase-pure Fe-NiCo2S4 for industrial anion-exchange membrane water electrolyzer

Precise doping into phase-pure structure is very challenging for industrial electrocatalysts keeping high activity and stability. Herein, a facile molten salt method is adopted to synthesize Fe-NiCo2S4 @NIF with a pure phase structure using NiFe foam (NIF) as substrate, achieving controllable Fe doping assisted by inner Fe element in NIF through trojan strategy. Physical characterizations and density functional theory (DFT) calculations reveal that Fe doping not only maintains mechanical strength but also optimizes the electronic structure and reduces *OOH adsorption energy barrier. Consequently, Fe-NiCo2S4 @NIF only needs a low overpotential of 325 mV to reach the industrial current density of 1000 mA cm−2 and run stably for 1000 h for oxygen evolution reaction (OER). The anion exchange membrane (AEM) water electrolyzer (Fe-NiCo2S4 @NIF//(Pt/C)) reaches the current density of 1000 mA cm−2 at a cell voltage of 1.83 V, which operates at the average energy efficiency of 72% for 100 h.