The Keggin-type Polyoxometalates Embedded In Sba-15 Mesoporous Molecular Sieve And Application

In the last years, the polyoxometalates have received increasing interests in the field of materials and catalysis, ensuring safer use and a more general applicability. SBA-15 is a very attractive member in mesoporous molecular sieve,which was made in 1998 due to its easy synthesis, adjustable pore size (in the range of 4.6-30.0 nm), thick pore walls (3.1-6.4 nm), great specific surface area and remarkable thermal stabilities. These properties make SBA-15 materials among the best candidates for a wide range of applications in the fields of catalysis and host-guest chemistry. In this paper, it is reported that polyoxometalates with Keggin structure are successfully immobilized on chemically modified mesoporous silica SBA-15. POM/SBA-15m is characterized by FT-IR spectroscopy, 31P MAS NMR, X-ray powder diffractometer, transmission electron microscopy and Thermogravimetric/Differential Thermal Analyzer, which show that the framework of SBA-15 and the Keggin structure of polyoxometalates are retained and herteropolyacid anions are finely dispersed on the pore wall of SBA-15. Upon leaching in ethanol at 60 oC for 7 hours, the loss of PW12O403-anions is not found. And we also describe the preparation and electrochemical behaviour of GCE modified with POM/SBA-15m complexes thin film. Cyclic Voltammetry has been used to characterize the chemically modified electrodes. The experimental results show that the modified electrodes have high stability and good recurence in aqueous acidic medium. The high stability results from the static interaction between polyoxometalates and the pore wall of SBA-15. After the modified electrodes of PW12/SBA-15m and PV2Mo10/SBA-15m infuse in 0.25 mol/L Na2SO4~H2SO4 for days, they are still kept the excellent electrochemical response. It is also found that modified electrodes are able to electrocatalytize the reduction of NO2-and ClO3-.