SELECTIVE CHEMICAL SENSORS FOR NO_2. DETECTION, USING CARBON NANOTUBE/POLYMER COMPOSITE NANOWIRES

摘要

Bare Gold electrodes modified with multi-walled carbon nanotube (MWCNT)/poly(aniline) and MWCNT/poly(pyrrole) composite nanowires were assembled for sensitive and selective detection of nitrites. Several electroanalytical parameters were investigated for the template synthesis of composite nanowires, such as different monomers; different purification and functionalisation procedures of MWCNTs. The morphology of the nanowires was investigated by Atomic Force Microscopy (AFM), and Inverted Optical Microscopy. These new chemical sensors based on nanocomposite materials were fully characterized by Differential Pulse Voltammetry (DPV) working at an applied potential of +900 mV vs. Ag/AgCl. The best analytical performances were observed working at (MWCNT)/poly(aniline) composite nanowire based electrodes, in terms of linear range of concentration (1.00×10~(-6)-1.00×10~(-3) M), limit of detection ( L.O.D. 1.70×10~(-6) M), sensitivity (31.85 A mol~(-1) L cm~(-2)), reproducibility (RSD % = 2), response time (8s), and higher selectivity towards common interfence. Finally, this nanostructured sensor prototype was tested in real samples of tap water, to which standard concentrations of nitrite were added, and subsequently evaluating the % of recovery (> 90 %). Among the sensors tested, those prepared with poly(aniline)/MWCNT composite nanowires showed the best analytical performances.