Deposition of Nickel Hydroxide Nanoparticles Derivatized from Nickel Chitosan Complex on Glassy Carbon Electrode for Oxidative Electrocatalysis

We demonstrate, for the first time, the chemical/electrochemical synthesis of uniformly dispersed nickel hydroxide nanoparticles (NPs) embedded in a chitosan (CH) membrane deposited on a glassy carbon (GC) electrode. The morphology of this composite was investigated by scanning electron microscopy (SEM). The SEM results show that NPs have a nano-globular structure in the range 10 ÷ 100 nm. This composite displays electrocatalytic activity toward oxidation of methanol in alkaline solution. The electrochemical properties of the resulting material deposited as a redox film have been investigated by cyclic voltammetry and chronoamperometric techniques. Using Lavirin’s theory the electron-transfer rate constant and the transfer coefficient were determined to be ks = 4.1 s–1 and α = 0.42, respectively, for a modifier film (ΓNi = 7.1 x 10–10 mol cm–2) on a GC electrode in 0.1 M sodium hydroxide solution. Chronoamperometric studies were also used to determine the catalytic rate constant for the catalytic reaction of the tested modifier with methanol (kch = 1.7 x 104 cm3 mol–1 s–1). The dependence of the methanol oxidation current on alcohol concentration is discussed. The modified electrode for methanol oxidation is characterized by simple preparation, good stability and good reproducibility.