In this paper, we systematically investigated the influence of fluoride on the morphology and electrochemical property of Co₃O₄ nanostructures for hydrazine detection. The results showed that with the introduction of NH₄F during the synthesis process of Co₃O₄, both Co(CO₃)0.5(OH)·0.11H₂O and Co(OH)F precursors would be generated. To understand the influence of F on the morphology and electrochemical property of Co₃O₄, three Co₃O₄ nanostructures that were respectively obtained from bare Co(CO₃)0.5(OH)·0.11H₂O, Co(OH)F and Co(CO₃)0.5(OH)·0.11H₂O mixtures and bare Co(OH)F were successfully synthesized. The electrochemical tests revealed the sensing performance of prepared Co₃O₄ nanostructures decreased with the increase in the fluoride contents of precursors. The more that dosages of NH₄F were used, the higher crystallinity and smaller specific surface area of Co₃O₄ was gained. Among these three Co₃O₄ nanostructures, the Co₃O₄ that was obtained from bare Co(CO₃)0.5(OH)·0.11H₂O-based hydrazine sensor displayed the best performances, which exhibited a great sensitivity (32.42 μA·mM-1), a low detection limit (9.7 μΜ), and a wide linear range (0.010-2.380 mM), together with good selectivity, great reproducibility and longtime stability. To the best of our knowledge, it was revealed for the first time that the sensing performance of prepared Co₃O₄ nanostructures decreased with the increase in fluoride contents of precursors.
Keywords: cobaltosic oxide; crystallinity; electrochemical activity; fluoride; precursor.