Anodic electrodeposition of iridium oxide particles on glassy carbon surfaces and their electrochemical/SEM/XPS characterization

• Anodic electrochemical deposition of IrOx on glassy carbon substrates from alkaline medium.
• Electrochemical characterization of the IrOx electrodic system.
• SEM characterization of electrodeposited iridium particles.
• XPS characterization of electrodeposited IrOx oxyhydroxide species.
• Electrocatalytic oxidation of semicarbazide in acid solutions.

In this study an electrodeposition procedure of hydrated Ir(III) and Ir(IV) oxyhydroxide species operating under anodic conditions and directly from aged alkaline solution containing 6 mM IrCl63− and 20 mM Cl− a ligand specie was defined for the surface modification of the glassy carbon electrode substrates. Optimum efficiency of iridium oxide deposition was obtained by cycling the potentials (100 mV s−1) between −0.7 V and 1.0 V vs. SCE. The SEM analysis reveals that the iridium oxide is uniformly distributed on the entire electrode surface with particles having a globular form. All particles, appear isolated or in aggregated structures with an average diameter comprised between 0.03 μm and 0.4 μm. The XPS curve fitting analysis reveals that the surface deposit is formed of hydrated Ir(III) and Ir(IV) oxyhydroxide species. The electrocatalytic activity of the GC/IrOx electrode toward the oxidation of semicarbazide under acidic condition (i.e., 50 mM HClO4) using cyclic voltammetry and chronoamperometry, was also investigated.