Low temperature growth of carbon nanotubes using chemical bath deposited Ni(OH)2 - An efficient Pt-free counter electrodes for dye-sensitized solar cells

A simple and facile chemical bath deposition (CBD) process was employed to prepare Ni catalyst through Ni(OH)2 on fluorine-doped tin oxide (FTO) surface and CNTs were successfully grown on FTO substrate by low-temperature chemical vapor deposition (CVD) method. The formation and surface morphologies of as-fabricated Ni(OH)2/FTO and CNT/FTO substrates were analyzed by X-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscope (FE-SEM) analysis. The fabricated CNT/FTO substrate was directly applied for DSSC application as a counter electrode (CE) and the CE behavior of CNT/FTO was evaluated through the cyclic voltammetry (CV) measurements using I−/I3− redox couple. Electrochemical impedance spectroscopy (EIS) and Tafel studies were used to investigate the kinetics of electron transfer and Nernst diffusion process of CNT/FTO CE towards I−/I3− redox electrolyte. The photo conversion efficiency (PCE) of CNT/FTO (7.36%) CE based DSSC was found to be superior than that of Sputter-Pt (6.65%) and TD-Pt (6.72%) based DSSCs.