A sensitive enzymeless hydrogen-peroxide sensor based on epitaxially-grown Fe 3O 4 thin film

Abstract

A novel and facile approach has been developed to synthesize thin films of magnetite (Fe 3O 4) 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 Fe 3O 4 at 300 °C. The as-synthesized epitaxial Fe 3O 4 was extensively characterized. The electrocatalytic activity of the epitaxial Fe 3O 4 thin-film sensor against hydrogen peroxide (H 2O 2) 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 ( R 2 = 0.996) with results obtained using a commercial HPLC-UV device. The sensor performance was robust and accurate in measuring H 2O 2 in some complex matrices. The advantages of relative simplicity and ease of mass production make the epitaxial Fe 3O 4 thin film promising candidate for use in sensing applications.