Synthesis and characterization of carbon-coated Cu-Ni alloy nanoparticles and their application in conductive films

In this paper, an efficient fabrication route is presented for carbon-coated Cu-Ni alloy nanoparticles (Cu_1-xNi_x@C NPs; x = 0–1.0) by means of electrical wire explosion under methane gas. The Cu-Ni binary system, which is considered to be an ideal isomorphous system, has carbon growth controllable by tuning the atomic fraction of Cu and Ni with largely different carbon solubility. As the Ni content increases, the average particle size and carbon layer thickness increase. It is notable that the carbon layer is very thin, <2 nm, regardless of the core size for pure Cu@C NPs. On the other hand, as the Ni content increases, the particle size dependence of the carbon-layer thickness becomes significant and the carbon layer is obviously tunable from amorphous to crystalline form. The high-temperature oxidation stability of Cu_1-xNi_x@C NPs is enhanced with increasing Ni content due to the higher thermal stability of carbon layers with greater thickness and high crystallinity. The conductive films were prepared using screen-printing of paste containing Cu_1-xNi_x@C NPs and the electrical resistivity was mapped according to the Ni content. The temperature stability of the sheet resistance and activation energy of oxidation for the conductive films increase with increasing Ni content.