Synthesis of Co3Fe7/CoFe2O4 incorporated porous carbon catalysts via 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 in situ calcination. Among the synthesized catalysts, Co₃Fe₇/CoFe₂O₄@NC-1, demonstrated outstanding catalytic reduction performance, with a reaction rate constant (k) 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 (E_onset = 0.99 V, E_1/2 = 0.83 V, J_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.