Crystal Structure‐ and Morphology‐Driven Electrochemistry of Iron Oxide Nanoparticles in Hydrogen Peroxide Detection

Abstract Various iron oxide nanoparticles with different morphologies are synthesized and subsequently tested for their conductivity and electrocatalytic activity toward hydrogen peroxide. The morphology and chemical and phase composition of iron oxide nanoparticles are evaluated employing scanning electron microscopy, X‐ray diffraction, ⁵⁷Fe Mössbauer spectroscopy, and Brunauer–Emmett–Teller specific surface area measurements. The electrochemical properties of the as‐prepared sensors are estimated by electrochemical impedance spectroscopy. It is found that α‐Fe₂O₃ nanoparticles with the sticks morphology exhibit the best conductivity response among all the tested phases and morphologies. Moreover, it is predicted that conductivity of different iron oxides can be connected with a number of vacancies in their crystal structure. Furthermore, the influence of surface area and porosity of the material on the conductivity can be omitted. Finally, the electrocatalytic activity of iron oxide nanoparticles toward hydrogen peroxide is confirmed by means of cyclic voltammetry. The obtained results perfectly reflect those derived from electrochemical impedance spectroscopy and indicate that glassy carbon electrodes modified with the sticks morphology of α‐Fe₂O₃ hold a huge potential for hydrogen peroxide detection.