Incorporation of Keggin-Type Phosphomolybdic Acid, Ionic Liquid and Carbon Nanotube Leading to Formation of Multifunctional Ternary Composite Materials: Fabrication, Characterization and Electrochemical Reduction/Detection of Iodate, Borate and Nitrite

Abstract

Single wall carbon nanotube substituted ionic liquids were synthesized successfully by esterification reaction of the carboxylated single wall carbon nanotubes (SWNTs) with hydroxyl ammonium ionic liquids (ILs) of the formula CH3N(CH2CH2OH)2(CnH2n+1)Br (n = 4, 8, 12), which subsequently reacted with molybdophosphoric acid (PMo12) to form three new ternary composite materials (SWNTs-ILCn-PMo12) (n = 4, 8, 12). The composites modified glass carbon electrodes were used to study electrochemical properties systematically through cyclic voltammetry method. The results showed that electronic conductivity of SWNTs moiety and ionic conductivity of ILs moiety in the composite materials played important roles in the electrochemistry and electrocatalysis. The length of alkyl carbon chain of the ionic liquids in the composite materials was also found to influence the electrochemical properties. The experimental results also showed that all the composites modified electrode can catalytically reduce and detect IO3−, BrO3− and NO2− with very high efficiency (low detection limit, short response time and wide linear range).