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

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_xFe_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_xFe_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_xFe_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.