New-style Hydrogen Peroxide Sensors Based On Metal Hexacyanoferrates/Pt/Carbon Materials

Hydrogen peroxide is a chemical threat to the environment and is recognized as one of the major factors in the development of important diseases. Due to its high activity, its stability and its selectivity toward the reduction of hydrogen peroxide, PB has been described as an "artificial enzyme peroxidase" and has been extensively used in the construction of electrochemical biosensors. Up to now, most of the research on PB-based composite materials for electrochemical sensing of hydrogen peroxide has focused on developing methods for the synthesis of nanostructured PB objects and their deposition onto various conductive materials, such as carbon nanotubes, graphenes, bulk metal substrates and other substrates. However, the performance of the composite materials relies not only on the properties of the individual components, such as the electron transport ability of the substrates and the catalytic activities of the PB, but also on the effective structural integration of the two components. Therefore, it is important to develop methods improving the intimate contact between the components, which depends directly on the experimental procedure of preparation of the electrodes. The main work is as follow:1. We prepare a triple-component sensor fabricated by freestanding Graphite felt (GF), Platinum nanoparticles (Pt) and Prussian blue (PB). Pt is ultrasonically-electrodeposited on GF to render the catalysts to the chemical deposition of PB. Cyclic voltammetric and amperometric measurements show that the double porous PB@Pt/GF sensor exhibits two pairs of well-defined redox peaks and a prominent electrocatalytic activity toward hydrogen peroxide reduction. This resulting sensor displays impressive results with regards to low detection limit of1.2×10-9M and very high detection sensitivity of40.9A·cm-2·M-1, using a potential work of0.0V.2. A novel composite of cobalt hexacyanoferrate nanoparticles (CoNP) and platinum nanoparticles (Pt) on carbon nanotubes (CNTs) is obtained by ultrasonically mixing of CoNP synthesized in microemulsion with CNTs chemically modified with platinum nanoparticles (Pt/CNTs). Cyclic voltammetric and amperometric measurements on glass carbon electrode showed that the composite (called CoNP-Pt/CNTs) exhibits a well-defined pair of redox peaks and a prominent electrocatalytic activity toward hydrogen peroxide reduction. Besides, the current response of CoNP-Pt/CNTs is94times higher than the response current of CoNP,27times than the one of CoNP-Pt,14times than the one of Pt/CNTs and8times than the one of CoNP/CNTs. This higher efficiency can be attributed to a remarkable synergistic effect between CoNP, PtNP and CNTs. This sensor shows a linear response to hydrogen peroxide concentrations ranging from0.2[iM to1.25mM with a detection limit of0.1μM, a maximum sensitivity of0.744A·M-1and a fast response time below2s.3. We deposit and disperse platinum clusters on carbon nanotubes via a chemically specific nucleation mechanism to fabricate Pt/CNTs hybrid. Prussian blue (PB) was catalytically synthesized by Pt nanoparticles from ferric ferricyanide aqueous solution to form PB@Pt/CNTs composite, and it was confirmed by transmission electron microscope (TEM). The obtained PB@Pt/CNTs composite was used to modify the glassy carbon electrode (GCE), developing an electrochemical sensor for detecting H2O2. The response time and sensitivity of this sensor were determined to be below5s and0.251A·M-1, respectively.