Laser-induced immobilization of an amorphous iron-phosphate/Fe 3 O 4 composite on nickel foam for efficient water oxidation.

A laser-induced immobilization strategy is applied to prepare an amorphous iron-phosphate/Fe 3 O 4 (L-FePO) composite on a nickel foam (NF) support. By laser-irradiating an iron hydrogen phosphate (FeHP) precursor, a melting and oxidation process leads to the generation of L-FePO with hierarchical pores and an amorphous structure. L-FePO shows exceptional electrocatalytic performance for the OER in an alkaline electrolyte, demonstrating an overpotential of 256 mV at 100 mA cm -2 , a Tafel slope of 71 mV dec -1 , and good stability over 100 h. The active Fe 3 O 4 , partially dissolved phosphate, and newly formed FeOOH species provide abundant active sites, contributing to the excellent OER performance.