Defect-rich FeOOH/FeCoAl-LDH/NF heterojunction electrocatalysts constructed via alkali-etching-induced reconstruction for enhanced oxygen evolution reaction

Developing efficient and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is essential for sustainable hydrogen production via electrochemical water splitting. However, existing catalysts suffer from limitations such as poor conductivity, insufficient structural stability, and a low density of active sites. Here, we present a two-step strategy-hydrothermal synthesis followed by controlled alkaline etching-to create a defect-rich FeOOH/FeCoAl-LDH/NF heterostructured electrocatalyst through Fe-dopant-mediated in-situ phase reconstruction. A series of Fe x Co y Al z -LDH/NF precursors with varying Fe/Co ratios were first synthesized to identify the optimal composition, and subsequent alkaline etching of the optimized Fe 1.3 Co 2 Al 3.3 -LDH/NF precursor induced selective Al 3+ leaching, in-situ FeOOH formation, and oxygen vacancy generation within the Co-O-Fe framework. The resulting E-Fe 1.3 Co 2 Al 3.3 -LDH/NF-72 catalyst integrates a low-crystallinity, defect-rich surface with enhanced interfacial charge-transfer kinetics, delivering a low overpotential of 267.8 mV at 50 mA cm −2 alongside excellent stability. This work provides a general defect-engineering strategy for high-performance non-precious metal OER electrocatalysts.