Electrocatalytic activity of a hybrid ormosil film containing phosphomolybdic acid toward prometon herbicide

ABSTRACT Organically modified silicate (whose abbreviation is ormosil) can be used to immobilize chemical species of interest for applications such as sensors and optical devices. Polyoxometalates (POMs) can be immobilized to the pores of the ormosil network to investigate their electroactive properties since they are widely used as electrocatalysts. However, few studies have explored the electrocatalytic properties of immobilized POMs in ormosil networks toward triazinic herbicides, which are extensively used in agriculture in the cultivation of grains and sugar cane. The work reported here describes the electrocatalytic activity of a hybrid film formed by an organically modified silica (ormosil) with 3-cyanopropyltriethoxysilane containing a POM, phosphomolybdic acid, toward prometon, a triazinic herbicide. Cyclic voltammetry and differential pulse voltammetry experiments were performed using as supporting electrolyte an aqueous solution of sulfuric acid at pH 1,0 and showed that this hybrid ormosil film deposited on gold electrode electroreduced prometon in a concentration range of 3,6 x 10-6 to 18 x 10-6 mol L-1. The potential value where the herbicide reduction ocurred was around 0,0 V vs. Ag / AgCl, lower than those found in the literature as for example + 0,75 V or -1,0 V vs. Ag/AgCl. With these features, the resulting film can be used for novel applications of environmental interest.