Construction On GCE Of Multidimensional Nanocomposite And In Situ FTIR Spectroelectrochemical Study

Two subjects, construction on GCE of multidimensional nanocomposite film and in situ FTIR spectroelectrochemical study have been investigated in detail.The first part of this dissertation includes five chapters. The characterization and application of nanocomposite were reviewed in Chapter 1. Chapter 2 was experimental section. In Chapter 3, self-assembly of molybdophosphate on a GCE constructed with choline(Ch) and electrocatalytic reduction of iodate was studied. In Chapter 4 and 5, the potential applications of 3D poly(N-acetylaniline) (PAANI) nanocomposite film in fuel cell and supercapacitor were investigated, respectively. In the second part, the method, experimental technique and the applications of in situ FTIR spectroelectrochemistry were reviewed in Chapter 6, and then the in situ FTIR spectroelectrochemical study of Ch constructed GCE was preliminarily explored. The main studies are as follows:First, Keggin-type molybdophosphate anion,α-PMo₁₂O₄₀^3-, has been self-assembled on the Ch/GCE through electrostatic interactions, andΓ₀^* is 2.1×10^-10 mol/cm² monolayer molybdophosphate electrode (α-PMo₁₂/Ch/GCE) prepared. It was found that theα-PMo₁₂/Ch/GCE exhibits strong electrocatalytic activity and sensitivity toward the reduction of IO₃^-. The content of IO₃^- in a table salt was determined with satisfactory results. This displayed that the Ch/GCE is promising in the field of constructing 2D electrochemical sensor.Then, we prepared a novel nanorods 3D matrix of PAANI and about 100nm Pt spherical nanocluster consisted of 8.5 ran in average size crystalline embedded string-of-beads like structural PAANI nanorods composites (nr-PAANI/nc-Pt) by cycling voltammetry(CV) on GCE. The PAANI/Pt/GCE has enhanced electrocatalytic activity toward methanol oxidation and has significantly reduced poisoning effect. The nano-PAANI polymeric coating on Pt nano-clusters provides a nano-thickness hydrophobic and conjugative environment for accumulating methanol, stabilizing the nano-structure, extracting intermediates and poisoning species. Nanoclusters were embedded in conducting polymer constructing 3D nanocomposite film array electrode in this study for the first time, which shows prominent advantages.In the meantime, the novel nanocomposite of palladium nanoclusters (nc-Pd) / nr-PAANI (nc-Pd/nr-PAANI) was synthesized. The results showed that the 9.5nm Pd crystallines( forming 50-500 run Pd spherical nanoclusters) are mainly grown on the ends of nr-PAANI, eventually the 3D novel network structure is formed through the nc-Pd chained by the nr-PAANI. We demonstrate that the PAANI film does have certain catalytic activity toward the reduction of oxygen, to the best of our knowledge, which has not been reported in the literature up to now. The Pd/PAANI composite has much higher activity than the individual PAANI film due to the existence of highly dispersed Pd nanoparticles. The oxygen proceeds a four-electron pathway through which the molecular oxygen is directly reduced to H₂O. This suggests the potential applications in the development of high-efficiency hydrogen-oxygen fuel cells.Electrochemical method was used to prepare multi-wall carbon nanotubes( MWCNTs)-PAANI nanocomposites by in situ electrochemical deposition PAANI on the surface of the MWCNTs. The uniform and 34 nm thickness PAANI coating strengthens and stabilizes 3D MWCNTs network structure. By the galvanostatic charge/discharge measurement, the specific capacitance of MWCNTs-PAANI is 463F/g, which is 12 time than that of MWCNTs/GCE and 9 time than that of PAANI/GCE. Excellent cyclic stability of MWCNTs-PAANI indicates that it has potential applications in supercapacitors.At last, FTIR reflection accessory was reconstructed, and a simple but efficient in situ thin-layer reflection FTIR spectroelectrochemical cell was designed and characterized. The spectral results of redox couple Fe(CN)₆^3-/Fe(CN)₆^4- showed that the cell has satisfactory performances and is suitable to be applied to spectroelectrochemical studies. The modification of Ch on GCE was investigated using FTIR subtractive spectrum technology. The results display the existence of the -C-O-C- bond, proving the covalently grafting mechanism. Electrochemical oxidation process of ascorbic acid (AA) at Ch/GCE in neutral solution was preliminarily studied. The results indicate that AA nears the positive charge center of the Ch/GCE, the electron exchange and catalytic redox reaction take places.