Cold H2–Ar plasma interaction with nickel α-hydroxide as a versatile nanofabrication tool for Ni@Cgr nanoparticles

Abstract

Taking advantage of its open structure and high reactivity, turbostratically disordered, single layered nickel hydroxyacetate was produced by forced hydrolysis in polyol and exposed to cold H₂–Ar (90 : 10) plasma to study its reactivity toward such reductive conditions. X-ray diffraction and transmission electron microscopy evidenced a quite complex phase transformation kinetics, with the simultaneous production of rhombohedral Ni₃C and cubic NiC_y (y ≪ 0.25), the former disappearing in favor of the latter, accompanied by a progressive carbon demixing from the cubic nanocrystals, leading to Ni@C_gr core–shell nanoparticles. These results are discussed hereafter, highlighting the role of the organic content of the hydroxide phase, mainly the intercalated acetate ions, which decomposed providing the carbon source for carbon implantation in the in situ formed metal nanoparticles.