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

Abstract

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.