Fabrication of bulk-modified carbon paste electrode containing α-PW12O403- polyanion supported on modified silica gel:: Preparation, electrochemistry and electrocatalysis

alpha-PW12O403- (PW12) supported on the surface of silica gel derivatized by 3-aminopropyl(triethoxy)silane (devoted briefly as SiNH3PW12) was synthesized and used as bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry. There is an ionic bonding character between PW12 and the surface amino groups of modified silica, which greatly improves the stability of SiNH3PW12-modified carbon paste electrode due to insolubility of silica gel in water. The SiNH3PW12 bulk-modified carbon paste electrode not only maintains the electrochemical activity of PW12, but also exhibits remarkable advantages of renewability, as well as simple preparation and inexpensive material. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of IO3- and hydrogen peroxide. The SiNH3PW12-CPE is successfully applied as an electrochemical detector to monitor IO3- in flow injection analysis (FIA). The catalytic peak current was found to be linear with the IO3- concentration in the range 5 x 10(-6) to 1 x 10(-3) mol L-1. The detection limit of the proposed method was found to be 3.1 x 10(-6) mol L-1 for IO3- determination. (C) 2007 Elsevier B.V. All rights reserved.