Bath temperature impact on morphological evolution of Ni(OH)₂ thin films and their supercapacitive behaviour

Nanostructured Ni(OH)₂ thin films were deposited over stainless steel (SS) and glass substrate via simple chemical bath deposition (CBD) method. NiCl₂:6H₂O were used as source of nickel and aqueous ammonia as a complexing agent. The coating process of Ni(OH)₂ material over substrate is based on the decomposition of ammonia complexed nickel ions at two different bath temperatures. The changes in structural, morphological and electrochemical properties are examined as an impact of bath temperature. XRD studies reveal formation of mixed phase of α and β at lower bath temperature (313 K) while, pure β phase of Ni(OH)₂ thin films deposited was observed at higher bath temperature (353 K). The morphological evolution from honeycomb structure to vertically aligned flakes over the substrate is observed as the influence of bath temperature. The supercapacitive performance based on the morphology examined by using cyclic voltammetric measurements in 1 M KOH. Themaximum specific capacitances of 610 and 460 F/g were observed for the vertical flake and honeycomb structured Ni(OH)₂ thin films, respectively.