Synthesis Of Polyaniline Nanocomposites And Their Applications In Electrochemical Sensing

Conducting polymer nanostructures have recently received special attention in nanoscience and nanotechnology because of their highly π-conjugated polymeric chains and metal-like conductivity, and they have been applied in chemical sensor, supercapacitors and fuel cells. Among the known conducting polymers, polyaniline (PANI) is one of the mostly studied conducting polymers owing to its facile synthesis, good environmental stability, tunable conductivity switching between insulating and semiconducting materials, and potential application in many areas. Recently, PANI nanocomposites have been successfully prepared, which expected to obtain an attractive robust and advanced hybrid material. In this dissertation, we demonstrate for the first time an interfacial polymerization method for the synthesis of high-quality PANI and PANI based carbon nanomaterials. Then ultra-high loading of Pt nanoparticles are controllably deposited on the surface of PANI or PANI based carbon nanomaterials. The prepared Pt hybrids show excellent electrocatalytic activity toward methanol oxidation and oxygen reduction. H2O2and glucose were used as two representative analytes to demonstrate the sensing performance of PANI/Pt and Pt/PANI/GNs modified electrode. The details are given as follows:1. IntrodutionIn this section, the characteristics and synthesis methods of the PANI nanofiber and their composites were introduced, and their applications in biochemistry and fuel cell were summarized. At last, the works and innovations of this dissertation were presented.2. Polyaniline/Pt Hybrid Nanofibers:High-Efficiency Nanoelectrocatalysts for Electrochemical DevicesA novel interfacial polymerization is used to prepare PANI nanofibers, then ultra-high loading of Pt nanoparticles are deposited on polyaniline. The obtained PANI/Pt composites were characterized by scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. The results show that ultra-high loading of Pt nanoparticles are uniformfully dispersed on PANI nanofibers. This PANI/Pt hybrids show excellent electrocatalytic activity toward methanol oxidation and oxygen reduction, it also performed good electricity response of the H2O2and glucose under the optimized conditions.3. Controllable Deposition of Platinum Nanoparticle Ensemble-on-Polyaniline/Graphene Hybrid as a Novel Electrode Material for Electrochemical Sensing We demonstrate for the first time an interfacial polymerization method for the synthesis of high-quality polyaniline modified graphene nanosheets (PANI/GNs), which represents as a novel type of graphene/polymer heterostructure. The interfacial polymerization at liquid/liquid interface allows PANI uniformly grows onto the surface of GNs. Then ultra-high loading of Pt nanoparticles are controllably deposited on the surface of PANI/GNs forming Pt/PANI/GNs hybrids. The obtained composites were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy and thermogravimetric analysis. This Pt/PANI/GNs hybrids show excellent electrocatalytic activity toward methanol oxidation and oxygen reduction. H2O2and glucose were used as two representative analytes to demonstrate the sensing performance of Pt/PANI/GNs modified electrode. It is found that this sensing element shows a high sensitivity and low detection limit for H2O2and glucose detections. The results demonstrate that the present Pt/PANI/GNs hybrids may be an attractive and advanced hybrid electrode material with great promise for construction of electrochemical sensors and biosensors.4. Controllable deposition of platinum nanoparticles on carbon nanotube as an electrocatalyst for direct methanol fuel cellsWe demonstrate a novel and very efficient interfacial polymerization method for the synthesis of highquality polyaniline-wrapped carbon nanotube (CNT@PANI), which represents as a novel type of CNT/polymer heterostructure. The interfacial polymerization at liquid/liquid interface is prone to form uniformly core-shell CNT@PANI composite due to the presence of π-π interaction between PANI and CNT walls. Then electrocatalytically active platinum nanoparticles (Pt NPs) are loaded on carbon nanotube (CNT) through introduction of electron-conducting PANI to bridge the Pt NPs and CNT walls with the presence of platinum-nitride (Pt-N) bonding and π-π bonding. The Pt NPs with controllable loading density are uniformly dispersed onto the CNT@PANI walls. The CNT@PANI/Pt hybrids possess exceptional electrochemical activity and exhibit excellent electrochemical stability, and therefore promise potential applications in direct methanol fuel cells.