Organic template-free synthesis of Ni-ZSM-5 nanozeolite: a novel catalyst for formaldehyde electrooxidation onto modified Ni-ZSM-5/CPE

A novel modified Ni-ZSM-5 nanozeolite was fabricated via an organic template-free hydrothermal route. The average particle size of Ni-ZSM-5 nanozeolite was calculated to be 85 nm by scanning electronic microscopy. Then, Carbon paste electrode (CPE) was modified by Ni-ZSM-5 nanozeolite and Ni2+ ions were then incorporated to the nanozeolite matrix. Electrochemical behavior of this electrode was investigated by cyclic voltammetry that exhibits stable redox behavior of Ni(III)/Ni(II) couple in alkaline medium. It has been shown that Ni-ZSM-5 nanozeolite at the CPE surface can improve catalytic efficiency of the dispersed nickel ions toward formaldehyde (HCHO) electrocatalytic oxidation. The values of electron transfer coefficient, charge-transfer rate constant and the electrode surface coverage were obtained to be 0.49, 0.045 s−1 and 4.11×10−8 mol cm−2, respectively. Also, the catalytic rate constant for HCHO and redox sites of electrode and diffusion coefficient were found to be 9.064×103 cm3 mol−1 s−1 and 8.575 ×10−6 cm2 s−1, respectively.