Electrocatalytic Oxidation of Formaldehyde onto Carbon Paste Electrode Modified with Hydrogen Titanate Nanotubes, Including Nickel Hydroxide

In this study, the hydrogen titanate nanotubes (HTNs) with a high specific surface area were applied for modification of carbon paste electrode (CPE). Then, a novel, cheap and efficient catalyst for formaldehyde electrocatalytic oxidation was developed by decorating Ni²⁺ ions on the surface of the modified electrode. A sensitive oxidation peak was observed at 0.62 V vs. Ag|AgCl|KCl (3 M) in 0.1 M NaOH solution for electrocatalytic oxidation of formaldehyde. It has been observed that HTNs at the surface of CPE can improve catalytic efficiency of the dispersed Ni²⁺ ions toward oxidation of formaldehyde. The values of electron-transfer coefficient, the mean value of catalytic rate constant, and diffusion coefficient for formaldehyde and redox sites were obtained to be 0.545, 2.65 × 10⁴ cm³ mol⁻¹ s⁻¹, and 3.97 × 10⁻⁶ cm² s⁻¹, respectively. The good catalytic activity, high sensitivity, and easy in preparation rendered the Ni-HTN/CPE to be a capable electrode for electrocatalytic oxidation of formaldehyde. Graphical abstract: .