Abstract
Ir oxide (IrOx) films, formed electrochemically on bulk Ir metal (Ir/IrOx) and also on sol‐gel (SG) derived non‐silica based nanoparticulate Ir, have been studied as material useful for the detection of hydrogen peroxide, with possible application as a glucose biosensor. H~2~O~2~ reduction and oxidation on Ir/IrOx and SG‐derived IrOx films, deposited on various substrates such as Pt, Ir and GC, have been compared to the H~2~O~2~ behavior at the bare substrate. It was found that H~2~O~2~ reduction proceeds on the underlying electrode substrate, while H~2~O~2~ oxidation is independent of the nature of the substrate, therefore occurring via the IrOx film. The reactivity of IrOx towards H~2~O~2~ oxidation is similar to that seen at Pt, although IrOx has the additional advantages of excellent stability, insensitivity to common interfering substances, biocompatibility and a linear range of detection, up to at least 12 mM H~2~O~2.~ At micromolar concentrations of H~2~O~2~, a second mode of detection, involving the catalyzed growth of IrOx films at Ir substrates, can be employed. These two methods of H~2~O~2~ analysis (oxidation/reduction and enhanced IrOx growth) can also be employed for glucose detection using IrOx‐based glucose biosensors.