Nanoporous gold particles modified titanium electrode for hydrazine oxidation

A nanoporous gold particles modified titanium electrode (Au/Ti) was prepared by using a hydrothermal method. Gold nanoparticles were stably immobilized on the Ti surface from a mixture of aqueous HAuCl4/polyethylene glycol (PEG) to form a nanoporous network texture. Electrocatalytic activity of the Au/Ti towards hydrazine oxidation in 1 M NaOH solution was assessed utilizing cyclic voltammetry (CV), linear scanning voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). At the Au/Ti electrode, hydrazine oxidation in 1 M NaOH took place at a potential of −0.55 V (vs. Ag, AgCl) which was 0.53 V less than polycrystalline Au electrode. The Au/Ti electrode also presented much larger current density of hydrazine oxidation than Au electrode. Cyclic voltammetric responses of the Au/Ti electrode showed an irreversible electro-oxidation process of hydrazine. Linear plots of the reduction peak current density from the CVs of the Au/Ti vs. hydrazine concentration provided a potential detection of low concentration hydrazine. The kinetic parameters such as the number of electrons transferred in rate-determining step and total numbers of electrons involved in the hydrazine oxidation were determined using CVs and LSVs. CVs at the Au/Ti electrode also illustrated (relatively) weak interactions of hydrazine with electrode surface at all stages of the hydrazine oxidation process. Further, EIS data showed significantly high electrocatalytic activity of the Au/Ti electrode for hydrazine oxidation in alkaline solutions.