title: Unusual neutral pH assisted electrochemical polymerization of aniline on a MWCNT modified electrode and its enhanced electro-analytical features.
abstract: Unusual electropolymerization of aniline to polyaniline (PANI) in a neutral pH solution has been successfully demonstrated using a multiwalled carbon nanotube (MWCNT) modified gold electrode (Au-MWCNT@PANIpH7). The modified electrode showed highly redox active surface confined peaks corresponding to the molecular transitions of leucoemeraldine-emeraldine and emeraldine-pernigraniline in pH 7 phosphate buffered solution (PBS), along with a low capacitance behavior, in contrast to the conventional acidic solution PANI systems. Control experiments in the absence of MWCNTs (i.e., Au/PANIpH7) and in an acidic medium, pH 2 (i.e., Au-MWCNT@PANIpH2), resulted in nil and poor redox features respectively. The physicochemical characterization of the MWCNT@PANIpH7 film by TEM, Raman spectroscopy, FTIR and UV-Vis revealed the presence of polaron type PANI structures on the MWCNT surface. More interestingly, MWCNT@PANIpH7 showed a highly selective electrocatalytic signal to ascorbic acid (AA) at a low oxidation potential, -15 mV vs. Ag/AgCl, without interference from nitrite, uric acid, dopamine, glucose, cysteine and citric acid in pH 7 PBS. Extended flow injection analysis yielded an excellent AA sensing response with a detection limit (signal-to-noise ratio = 3) of 42 nM, which is better than that of the conventional acid assisted MWCNT@PANIpH2 and MWCNT systems.
authors.affiliation: Environmental and Analytical Chemistry Division, School of Advanced Sciences, Vellore Institute of Technology University, Vellore-632014, India. askumarchem@yahoo.com.
authors.forename: Nandimalla
authors.initials: N
authors.lastname: Vishnu
authors.forename: Annamalai Senthil
authors.initials: AS
authors.lastname: Kumar
authors.forename: K Chandrasekara
authors.initials: KC
authors.lastname: Pillai
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D037742:Nanotubes, Carbon / Q000737:chemistry*; D058105:Polymerization
chemical_list: D000814:Aniline Compounds; D037742:Nanotubes, Carbon; C023650:aniline