Nickel (II) lignosulfonate as precursor for the deposition of nickel hydroxide nanoparticles on a glassy carbon electrode for oxidative electrocatalysis

We demonstrate, for the first time, the chemical/electrochemical synthesis of uniformly dispersed nickel hydroxide nanoparticles (Ni(OH)2-NPs) embedded in an adsorbed lignosulfonate layer (LS) deposited on a glassy carbon (GC) electrode. This approach is based on the oxidative deposition of Ni(II) lignosulfonates (Ni-LS) followed by Ni(OH)2-NP precipitation in alkaline electrolyte. The morphology of this composite was investigated by scanning electron microscopy (SEM). The SEM results show that the NPs have a nano-globular structure in the range ca. 50–200 nm. The composite displays reversible electrochemical transition due to a Ni(II)/Ni(III) redox couple and electrocatalytic activity leading to the oxidation of methanol in alkaline solution. The electrochemical properties of the resulting material deposited as a redox film were investigated by cyclic voltammetry and chronoamperometry techniques. Using Laviron'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 = 2.5 × 10−9 mol cm−2) in 0.1 M sodium hydroxide electrolyte. Chronoamperometric studies were used to determine the catalytic rate constant for the catalytic reaction of the tested modifier with methanol (kch = 1.0 × 104 cm3 mol−1 s−1). The dependence of the methanol oxidation current on alcohol concentration is discussed. The modified electrode for methanol oxidation offers simple preparation, good stability and reproducibility.