F‐Doped CoFe Bimetallic Heterostructure Electrocatalyst with Ultra‐Low Impedance for High‐Current‐Density Alkaline Hydrogen Evolution

Abstract The electrolysis of water for hydrogen production has gained increasing attention as a sustainable and efficient method to obtain high‐purity green hydrogen. The development of efficient catalysts for hydrogen evolution is crucial in order to achieve this target under industrial conditions. The objective of this work is to synthesize a highly efficient F‐Co x Fe y (PO n ) z /IF catalyst with ultra‐low impedance for hydrogen evolution in electrolytic water by incorporating metal phosphatides into metal oxide nanoclusters through a controlled two‐step process involving melting and electrodeposition. The nano‐heterostructure of F‐Co x Fe y (PO n ) z /IF exhibits a low overpotential of 276 mV at a current density of 1000 mA cm −1 , while having an electrochemical impedance comparable to commercial Pt/C/CP (0.41 Ω), and long‐term stability up to 200 h in 1 M KOH electrolyte. The synergistic effect of crystal/amorphous heterojunctions, F doping, and oxygen vacancies further enhances the kinetics of water cracking. Impressively, when combined with NiFeCo LDH/NiS/NF as membrane electrodes, F‐Co x Fe y (PO n ) z /IF || NiFeCo LDH/NiS/NF achieves a water decomposition voltage of 2.03 V at a current density of 1000 mA cm −2 and demonstrates stable operation for over 500 h, showing great potential for large‐scale commercial production.