Synthesis of Co ₃ Fe ₇ /CoFe ₂ O ₄ incorporated porous carbon catalysts <i>via</i> molten salt method: applications in the oxygen reduction reaction and 4-nitrophenol reduction

Developing high-performance, multifunctional non-precious metal catalysts is essential for enhancing the efficiency of future energy utilization. In this study, four types of magnetic, recyclable Co₃Fe₇/CoFe₂O₄ incorporated porous carbon composite catalysts were synthesized using citric acid as the carbon source and ammonium chloride (NH₄Cl) as the salt medium. Iron and cobalt salts, in four different proportions, were uniformly incorporated using freeze-drying technology and subsequently processed through <i>in situ</i> calcination. Among the synthesized catalysts, Co₃Fe₇/CoFe₂O₄@NC-1, demonstrated outstanding catalytic reduction performance, with a reaction rate constant (<i>k</i>) of 0.031 min^-1, along with excellent cycle stability for 4-NP. The resulting Co₃Fe₇/CoFe₂O₄@NC-3 catalyst exhibited good ORR activity in an alkaline medium (<i>E</i> _onset = 0.99 V, <i>E</i> _1/2 = 0.83 V, <i>J</i> _L = -5.2 mA cm^-2), along with long-term durability and resistance to methanol poisoning. These hybrid materials hold promise as non-precious metal electrocatalysts for fuel cell ORRs and introduce a new class of catalytic candidates for 4-NP reduction.