Fabrication of bulk-modified carbon paste electrode containing alpha - PW sub(12)O sub(40) super(3-) polyanion supported on modified silica gel: Preparation, electrochemistry and electrocatalysis

alpha -PW sub(12)O sub(40) super(3-) (PW sub(12)) supported on the surface of silica gel derivatized by 3-aminopropyl(triethoxy)silane (devoted briefly as SiNH sub(3)PW sub(12)) 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 PW sub(12) and the surface amino groups of modified silica, which greatly improves the stability of SiNH sub(3)PW sub(12)-modified carbon paste electrode due to insolubility of silica gel in water. The SiNH sub(3)PW sub(12) bulk-modified carbon paste electrode not only maintains the electrochemical activity of PW sub(12), 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 IO sub(3) super(-) and hydrogen peroxide. The SiNH sub(3)PW sub(12)-CPE is successfully applied as an electrochemical detector to monitor IO sub(3) super(-) in flow injection analysis (FIA). The catalytic peak current was found to be linear with the IO sub(3) super(-) concentration in the range 5 x 10 super(-6) to 1 x 10 super(-3) mol L super(-1). The detection limit of the proposed method was found to be 3.1 x 10 super(-6) mol L super(-1) for IO sub(3) super(-) determination.