Fabrication and characterization of magnetic nanoporous Cu/(Fe,Cu)3O4 composites with excellent electrical conductivity by one-step dealloying

In the present study, magnetic nanoporous Cu(NPC)/(Fe,Cu)3O4 composites with tunable magnetism and excellent conductivity were fabricated by a facile one-step dealloying process. Three ternary Al-Cu-Fe alloys with different compositions were chosen as the precursors to carry out the dealloying process in a 20 wt% NaOH solution under free corrosion conditions. The microstructure of these NPC/(Fe,Cu)3O4 composites have been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM) with nanobeam-EDX (NB-EDX). These NPC/(Fe,Cu)3O4 composites are composed of a NPC matrix with ligament/channel sizes of 20-40 nm and octahedral (Fe,Cu)3O4 embedded particles of 600-800 nm. The formation of these composites has been discussed based upon the surface diffusion of Cu adatoms and oxidation of Fe/Cu adatoms during dealloying. The N2 absorption/desorption results show that the NPC/(Fe,Cu)3O4 composites have a high surface area of up to 25.24 m2 g-1. The maximum values of the magnetic parameters of these NPC/(Fe,Cu)3O4 composites can reach 27.3 emu g-1, 7.7 emu g-1 and 218.5 Oe for the saturation magnetization, remanence and coercivity, respectively. The magnetic properties and the ratio of NPC : (Fe,Cu)3O4 in the NPC/(Fe,Cu)3O4 composites can be tuned by simply changing the Cu/Fe ratio in the Al-Cu-Fe precursor alloys, while keeping their excellent electrical conductivity. These functional composites will find potential applications in sensors, information storage, medical diagnostics, and so forth.