Morphological characteristics of Ni sulfides fabricated by chemical vapor deposition

Ni sulfides were formed by reacting Ni substrates with gaseous sulfur, and then their microstructures were investigated. Ni sulfides consisted of four distinct layers, i.e., the topmost thin film layer (I), dense thick film layer (II), coarse particulate layer (III), and innermost fine particulate layer (IV). XRD and electrochemical analyses demonstrated that layers I, II and IV were NiS2, NiS and Ni3S2, respectively and layer III was a transient layer where Ni3S2 was converted into NiS by Ni3S2 + S → NiS reaction.