A sensitive enzymeless hydrogen-peroxide sensor based on epitaxially-grown Fe3O4 thin film

A novel and facile approach has been developed to synthesize thin films of magnetite (Fe3O4) with epitaxial needle-like columnar grains on titanium nitride (TiN) buffered substrate using DC magnetron reactive sputtering. TiN buffer layer was first sputtered onto a substrate at 550 °C as a preferable substrate for growth following sputtering of epitaxial crystalline Fe3O4 at 300 °C. The as-synthesized epitaxial Fe3O4 was extensively characterized. The electrocatalytic activity of the epitaxial Fe3O4 thin-film sensor against hydrogen peroxide (H2O2) reduction was rapid with a response time less than 5 s. The sensor also exhibited an acceptable stability, a satisfying sensitivity of 432.2 μA mM−1 cm−2, good specificity to the substrate, a dynamic working range of up to 0.7 mM and a low detection limit of 1.0 μM. The sensor performance correlated well (R2 = 0.996) with results obtained using a commercial HPLC-UV device. The sensor performance was robust and accurate in measuring H2O2 in some complex matrices. The advantages of relative simplicity and ease of mass production make the epitaxial Fe3O4 thin film promising candidate for use in sensing applications.

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► Simple material synthesis, easy preparation and conducive for mass production.
► High sensitivity (432.2 μA mM−1 cm−2) and low detection limit (1.0 μM at S/N = 3).
► Fast response (≤5 s), good specificity, stability, and accuracy in real samples.