Fabrication And Application Of Metal Oxide Nano-material Modified Electrode

Nano-materials have been found broad utility in electrochemical catalytic applications. In this paper, we fabricated several kinds of metal oxide nanomaterial and then modified them on the electrode to form different sensors. Further more, we explored the capability and application of the sensors. The main contents are listed as follows:1. Shuttle-like copper oxid (CuO) was prepared by a hydrothermal decomposition process. The resulting material was characterized by Scanning electron microscopy, X-ray diffraction and then immobilized on the surface of a glassy carbon electrode modified with a film of poly(thionine). A pair of well-defined and reversible redox peaks of Hg²⁺ on nano-CuO/PTH/GCE was observed in 0.10 M pH 7.0 phosphate buffer solutions. The anodic and cathodic peak potentials of Hg²⁺ were at 0.260 V and 0.220 V (vs. Ag/AgCl), respectively. The modified electrode displayed excellent amperometric response for Hg²⁺, with a linear range from 40 nM to 5.0 mM and a detection limit of 8.5 nM at a signal-to-noise ratio of 3. The sensor exhibited high selectivity and reproducibility and was successfully applied to determine Hg²⁺ in water samples.2. A sensitive hydrazine sensor has been fabricated using copper oxide nanoparticles modified glassy carbon electrode (GCE) to form nano-copper oxide/GCE. The nano-copper oxide was electrodeposited on the surface of GCE in CuCl2 solution at -0.4 V and was characterized by Scanning electron microscopy (SEM) and X-ray diffraction (XRD). The prepared modified electrode showed a good electrocatalytic activity toward oxidation of hydrazine. The electrochemical behavior of hydrazine on nano-copper oxide/GCE was explored. The oxidative current increased linearly with improving concentration of hydrazine on nano-copper oxide/GCE from 0.1μM to 600μM and detection limit for hydrazine was evaluated to be 0.03μM at a signal-to-noise ratio of 3. The oxidation mechanism of hydrazine on the nano-copper oxide/GCE was also discussed. The fabricated sensor could be used to determine hydrazine in real water.3. Hollow CuO/Fe₂O₃ hybrid microspheres with small uniform holes were synthesized using a convenient hydrothermal method and were applied to fabricated an amperometric sensor for kojic acid. The resulting materials were characterized by Scanning electron microscopy (SEM) and X-ray diffraction (XRD) and then were immobilized into the chitosan (Chi) matrix onto a glassy carbon electrode to obtain CuO/Fe₂O₃-Chi/GCE. The potential utility of the constructed electrodes were demonstrated by applying them to the analytical determination of kojic acid concentration. The electrochemical behavior of kojic acid on CuO/Fe₂O₃-Chi/GCE was explored. The modified electrode displayed excellent amperometric response for kojic acid with a linear range from 0.2μΜto 674μΜwith a detection limit of 0.08μΜat a signal-to-noise ratio of 3. In order to validate feasibility, the CuO/Fe₂O₃-Chi/GCE has been used for quantitative detecting kojic acid in real samples.4. Two different hydrogen peroxide sensors were constructed with Ni/Al and Co/Al layered double hydroxides (LDHs) modified glassy carbon electrodes (GCE). Ni (Co)/Al-LDHs were synthesized by electrochemical method and were characterized by scanning electron microscopy (SEM) and Energy dispersive spectrometry (EDS). The advantages and shortcoming of the two hydrogen peroxide sensors were described in detail. Compared to Co/Al-LDHs modified electrode, sensors fabricated by Ni/Al-LDHs showed quicker heterogeneous electron transfer rate constants (ks), lower detection and better reproducibility. But Co/Al-LDHs modified electrode held the advantages of wider linear range and higher sensitivity. Further more, the different catalytic redox mechanisms of hydrogen peroxide on the Ni/Al/GCE and Co/Al/GCE were firstly comparatively explored.