Electrochemical Determination Of Eu(Ⅲ) And Hydrogen Peroxide Based On Lab6Electrode

Lanthanum hexaboride (LaB6) is an extremely hard inorganic compound, with high conductivity, high melting point and chemical stability. It is widely used in modern technology as an excellent thermionic electron emission source because of its preeminent physical and chemical properties. In1968, it was first used as the electrochemical working electrode for determination of Eu3+. The first part of this paper is about the preparation of the LaB6electrode using the paraffin as a binder. The performance of the electrode was initially assessed by cyclic voltammetry (CV). Taking into account the tightness of adhesion, and the electrochemical current response, many different quality ratios of these two substances were tried, and the results showed that the quality ratio of5:1(LaB6:paraffin) was best for the electrode response signal. The electrode exhibited a high sensitivity, good linear range for the determination of the Eu3+with the0.2mol-L-1pH5.5HAc-NaAc solution as the buffer. The experimental results showed that the LaB6electrode using paraffin as a binder is not only easy to preparation but also with higher selectivity and sensitivity than previous work.The second part of the research work is about the electrochemical modified electrode. We intended to find a good modified LaB6electrode which had a better electrochemical response than pyrolytic graphite electrode. By using many different modifiers such as Nafio、GNP、PDDA、DDAB、 MWNTs and SDS, we found that SDS/MWNTs/LaB6electrode showed a good CV response to Eu3+. The performance of the modified electrode was initially assessed by CV, the charge-transfer coefficient (a) and the electron-transfer rate constant (ks) were discussed. The modified LaB6electrode exhibited a good linear dependence on the concentration of Eu3+from40μmol·L-1tol.7mmol·L-1.A novel hydrogen peroxide (H2O2) sensor based on LaB6electrode was reported in the third part. By using the catalysis of the y-Fe2O3nanoparticles, we fabricated y-Fe2O3-LaB6sensor for the determination of hydrogen peroxide. The performance of the sensor was initially assessed by CV and amperometric i-t curve methods. In phosphate buffer (pH7.0,0.1mol·L-1), the y-Fe2O3-LaB6sensor exhibited a good linear dependence (R=0.9997) on the concentration of H2O2from2.0x10-7mol·L-1to6.0x10-4mol·L-1, a high sensitivity of2.01x107μAM-1cm-2and a detection limit of6.34x10-8mol·L-1. Furthermore, the sensor was also good resistant towards typical inorganic salts and some biomolecules. Our developed electrochemical sensor provides an attractive alternative choice for the determination of H2O2.