Novel polymeric zinc phthalocyanine for electro-oxidation and detection of ammonia

Abstract

The design and development of new catalysts with low cost, high selectivity, and sensitivity for the electrochemical sensor applications is of huge interest. In this report, novel zinc tetra [4-[2-(1H-benzimidazol-2-yl) phenoxy]] phthalocyanine (ZnTBImPc) is prepared in a pure state with 87% yield. The characterization of the ligands and complex is carried out by combination of techniques like elemental analysis, ultraviolet-visible (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), mass spectral, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and electrochemical techniques. FTIR is useful in monitoring the progress of the reaction. The benzimidazole moiety of ZnTBImPc undergoes electropolymerization and thin, uniform polymeric layer deposits on the glassy carbon surface. The polymeric film was characterized by impedance spectra and charge transfer studies. The fabricated polymeric film electrode is applied for voltammetric sensing of ammonia which showed linear characteristics in 0.1 to 1.0 mu M concentration range. The LOD was 30 nM with sensitivity of 237.25 mu A mu M-1 cm(-2). The efficiency and sensitivity of ammonia oxidation at the poly(ZnTBImPc) are compared with the composite hybrid electrode of poly(ZnTBImPc) and carbon nanoparticle (CNP). The amperometric sensing of ammonia showed linear behavior in 50 to 500 nM concentration range. The RDE experiment revealed that the number of electrons involved in the ammonia oxidation is nearly 3. The polymeric electrode was subjected to the interference studies to evaluate the selectivity of the fabricated electrode and found that the co-existing molecules do not show interference during the detection of ammonia. [GRAPHICS] .