Amperometric ammonium ion sensor based on polyaniline-poly(styrene sulfonate-co-maleic acid) composite conducting polymeric electrode

Two kinds of polyaniline (PANI)-poly(styrenesulfonate-co-maleic acid, sodium form) (PSSMA) composite films, PANI-PSSMA (I) and PANI-PSSMA (II), were prepared and their NH4+-sensing properties were studied. PANI-PSSMA (I) was prepared by incorporating PSSMA anions into a PANI/Au/Al2O3 plate with a cyclic voltammetry (CV) method, while electropolymerization of PANI on a PSSMA/Au/Al2O3 plate was used to prepare another composite electrode of PANI-PSSMA (II)/Au/Al2O3. Compared with PANI-PSSMA (I), PANI-PSSMA (II) exhibited high sensitivity to NH4+ due to its fibrous morphology and high porosity. The maximum sensitivity (12 μA mM−1) was obtained with a PANI-PSSMA (II)/Au/Al2O3 electrode, where PSSMA was prepared by casing 12 μl 0.5 wt.% PSSMA solution and PANI was electropolymerized with CV method for cycle number of 5.