Electrochromic and electrochemical supercapacitive properties of Room Temperature PVP capped Ni(OH)2/NiO Thin Films

• Nanosize (34.36 and 48.10 nm) PVP capped Ni(OH)2 thin films were obtained from annealed films prepared by solution growth method.
• Nano flakes of length from ∼ 850 nm for the as-deposited film at room temperature to ∼ 700 nm for the film annealed at 400 °C were obtained.
• The Ni(OH)2 thin films showed highly porous morphology between the interconnected nanoflakes.
• The Ni(OH)2 films showed a band gap energy between 2.10 and 2.80 eV which could be attributed to effect of capping agent.
• The specific capacitance value of 1154.86 F/g is obtained for the as deposited Ni(OH)2 film on stainless steel at a scan rate of 10 mV/s

Porous-structured Ni(OH)2 and NiO thin films are good materials to enhance the performance of electrochromic devices as they provide an easy pathway for electrolyte penetration required for the improvement of electrochemical (EC) activity. In this paper, we present the results of our room temperature chemical bath deposition (CBD) of highly porous nanostructured PVP-capped Ni(OH)2/NiO thin films. We investigate the effects of post-deposition thermal treatment and the contribution of the substrate surface on the morphological, structural and electrochemical properties of these films as well as the role of the capping agent during the film growth process. Randomly oriented and well interconnected nanorods of individual lengths of about 600 nm were deposited on both stainless steel and Fluorine doped tin Oxide (FTO). The incorporation of PVP helps to moderate the size and length of the nanorods in the films as well as delayed the transformation of nickel hydroxide to oxide films. The optical density and the colouration efficiency obtained for the as-deposited (Ni(OH)2 films are 0.985 and 55.89 cm2/C respectively. The highest specific capacitance of 1184.52 F/g is obtained for the as-deposited film on stainless steel. We can deduce that the incorporation of PVP in the films enhanced the electrochemical capacitive properties of the Ni(OH)2 films to a very good extent.

The Micrographs show interconnected nanoflakes. The value of 1154.86 F/g is obtained for the as deposited Ni(OH)2 film on ss at a scan rate of 10 mV/s.Figure optionsDownload as PowerPoint slide