CHRONOPOTENTIOMETRIC DEPOSITION / DISSOLUTION KINETICS AND TEXTURAL ANALYSIS OF Ni-Fe OXY ..........

Hydrogen evolution and peroxide generation reactions are used to electrochemically deposit nano oxy hydroxides of Ni and Fe from a sulfate-based solution. It can be seen through chronopotentiometric and chronoamperometric transients that charge-transfer limits cause non-faradaic, anomalous co-deposition, which increases the creation of -Ni(OH)2. During anodic dissolution, iron rich films are preferentially oxidised by two-electron-transfer with reduced coulombic charge, as opposed to the cathodic cycle. The kkl family planes are indexed along with d-spacing data using a self-designed computer simulation tool written in MS-Visual Studio 'Crystalsim.' For both Ni and Fe hydroxides, an O-H stretching signal was identified using FTIR. In the presence of NO3- rather than H+, acicular to nano-sphered morphology was seen, with an average grain size of about 25 nm. Diffusion restrictions of Ni2+ increase grain growth rate when cathodic current density increases, and e- transfer rate of Fe2+ increases. At lower cathodic current densities, deposition kinetics is controlled by charge transfer, but at higher current densities, diffusion is constrained towards the cathodic interface due to a shift in concentration overpotential.

Please see the link :- https://www.ikprress.org/index.php/JACSI/article/view/3853