Electrodeposition of CoFeS nanoflakes on Cu2O nanospheres as an ultrasensitive sensing platform for measurement of the hydrazine and hydrogen peroxide in seawater sample

Abstract

Nanoarchitectured design of the metal sulfides with highly available surface and abundant electroactive centers and using them as electrocatalyst for fabricate the electrochemical sensors for the detection of hydrazine (N₂H₄) and hydrogen peroxide (H₂O₂) is challenging and desirable. Herein, Cu₂O nanospheres powder is firstly prepared using chemical reduction of copper chloride and then drop-casted on the glassy carbon electrode (GCE) surface. In the next step, CoFeS nanoflakes are electrodeposited on Cu₂O nanospheres by cyclic voltammetry method to form CoFeS/Cu₂O nanocomposite as a detection platform for measuring N₂H₄ and H₂O₂. Accordingly, Cu₂O nanospheres are not only used as substrate, but also guided the CoFeS nanoflakes to adhere to the electrode surface without need to any binder or conductive additive, which enhances the electrical conductivity of the sensing active materials. As the hydrazine sensor, the CoFeS/Cu₂O/GCE displayed wide linear ranges (0.0001-0.021 mM and 0.021-1.771 mM), low detection limit (0.12 μM), very high sensitivities (103.33 and 21.23 mA mM^-1 cm^-2), and excellent selectivity. The as-made nanocomposite also exhibited low detection limit of 1.26 μM for H₂O₂ sensing with very high sensitivities (12.31 and 3.96 mA mM^-1 cm^-2) for linear ranges of 0.001-0.03 mM and 0.03-2.03 mM, respectively, and negligible response against interfering substances. The superior analytical performance of the CoFeS/Cu₂O for N₂H₄ electro-oxidation and H₂O₂ electro-reduction can be attributed to structure stability, high electroactive surface area, and good availability to analyte species and electrolyte diffusion. Moreover, to examine the potency of the prepared nanocomposite in real applications, the seawater sample was analyzed and results display that the CoFeS/Cu₂O/GCE can be utilized as a reliable and applicable platform for measuring N₂H₄ and H₂O₂.

Keywords: Amperometric sensor; Cobalt iron sulfide nanoflakes; Copper (I) oxide nanospheres; Electrodeposition; Hydrazine detection; Hydrogen peroxide detection.