Preparation And Application Of Nano-Co₃O₄ Composite Materials

Since the 20th century,electrochemiluminescence（ECL）technology has made vigorous development.As a simple and efficient detection technology,it has a wide range of applications in environmental detection,food safety,life monitoring and other fields.In this paper,nano-Co₃O₄ and their composite materials were taken as the main research objects.Nano-Co₃O₄,Co₃O₄@Ag₂O and Co₃O₄@NiO were prepared by electrospinning technology combined with high temperature calcination.And three kinds of ECL sensors are constructed to realize sensitive detection of ascorbic acid（AA）,glucose and Hydrogen peroxide（H₂O₂）respectively.The specific contents are as follows:1.A novel ECL sensor based on Co₃O₄/Cd Te/GCE for the determination of ascorbic acidNanofibers were prepared by mixing cobalt nitrate（Co（NO₃）₂·6H₂O）with polypropylene alcohol（PVA）by electrospinning.The dried nanofibers were calcined at500℃ for 2 h to obtain nano-Co₃O₄.Co₃O₄/Cd Te/GCE ECL sensor was fabricated based on Cd Te and Co₃O₄.The ECL signal of Luminol was enhanced for two reasons.First,the larger pores of Co₃O₄ absorbed more luminol.Second,there was a synergistic interaction between Cd Te and Co₃O₄.With the increase of AA concentration,the ECL signal of Luminol gradually increased.Under optimized conditions,the logarithm of AA concentration and the ECL intensity had a linear relationship in the range of2.0×10^-10 to 1.0×10^-4mol·L^-1,and the detection limit was 6.7×10^-11mol·L^-1（S/N=3）,which provided a new method for the determination of AA in human serum.2.Determination of glucose on an ECL sensor based on TMPP-Zn/Co₃O₄@Ag₂O/Ru（bpy）₃²⁺/MWNTsCo（NO₃）₂·6H₂O,silver nitrate（Ag NO₃）,polymethyl methacrylate（PMMA）and polyacrylonitrile（PAN）were blended to prepare nano-fibers by electrospinning method.The fibers were then calcined at high temperature to prepare Nano-Co₃O₄@Ag₂O.The preparation conditions were optimized,and the nanoparticles were characterized by XRD and SEM.Ru（bpy）3²⁺was fixed on the surface of glassy carbon electrode（GCE）by MWNTs,and then Co₃O₄@Ag₂O and TMPP-Zn were modified on the GCE with Ru（bpy）3²⁺in turn.The ECL signal of Ru（bpy）3²⁺-TPr A system was enhanced due to the synergistic interaction of Co₃O₄@Ag₂O and TMPP-Zn.With the addition of glucose,the ECL signal of the system also increased.So a new method for determination of glucose content was established.The results showed that the sensor had a wide detection range(1.0×10^-9～5.0×10^-4mol·L^-1)and a low detection limit(3.3×10^-10mol·L^-1),which realized the sensitive determination of glucose in human serum.3.Co₃O₄@NiO/HRP/MWNTs ECL sensor for detection of H₂O₂Co（NO₃）₂·6H₂O,nickel acetate（Ni（CH₃COO）2·4H₂O）and PMMA,PAN were blended to prepare nano-fibers by electrospinning method.Nano-Co₃O₄@NiO was prepared by calcining the above nanofibers at high temperature,and the preparation conditions were optimized.MWNTs treated with glutaraldehyde were fixed on the surface of GCE to fix horseradish peroxidase（HRP）on the electrode surface as much as possible through the condensation of hydroxyl aldehyde and dehydration condensation of amino and carboxyl group.Nano-Co₃O₄@NiO was modified on the surface of HRP,and the ECL sensor of Co₃O₄@NiO/HRP/MWNTs was fabricated.HRP was regarded as the catalyst of Luminol-H₂O₂ system,which can amplify ECL signal.Co₃O₄@NiO had a large pore and specific surface area to facilitate electron transmission in the system.And the synergistic effect of Co₃O₄ and NiO can significantly enhance ECL signal to realize the sensitive detection of H₂O₂.The sensor had a wide detection range(9.8×10^-6～9.8×10^-3mol·L^-1)and a low detection limit(3.27×10^-6mol·L^-1),which can be applied to the accurate determination of H₂O₂ in food processing field.