Abstract:Effect of conditions of deposition of palladium onto a composite polymeric film Nafion-polyaniline on the properties of the system thus obtained is studied. It is shown that the effect of the said conditions on the character of distribution of palladium in a polymer may be used when estimating electrocatalytic potentialities of such composites.
“…Recently, extensive work has been focused on Nafion ® membranes modified with conducting polymers, such as polyaniline [22], polyaniline/silica [23] paying special attention to the methanol crossover in the composite membranes. It is worth noting that the mix of electronic conductivity of polyaniline with the ionic conductivity of cation-exchange membranes has also promoted the study of these composites for electrode modifications [24][25][26][27][28].…”
“…Recently, extensive work has been focused on Nafion ® membranes modified with conducting polymers, such as polyaniline [22], polyaniline/silica [23] paying special attention to the methanol crossover in the composite membranes. It is worth noting that the mix of electronic conductivity of polyaniline with the ionic conductivity of cation-exchange membranes has also promoted the study of these composites for electrode modifications [24][25][26][27][28].…”
“…Nevertheless, very few teams have studied the Nafion−PANI composite membranes. Nafion−PANI composites have been studied mostly for electrode modifications in order to mix the electronic conductivity of PANI and the ionic conductivity of Nafion. − 1 Structure of Nafion…”
Section: Introductionmentioning
confidence: 99%
“…Nafion-PANI composites have been studied mostly for electrode modifications in order to mix the electronic conductivity of PANI and the ionic conductivity of Nafion. [19][20][21][22][23] Prior to this work, we have demonstrated the possibility of improving the permselectivity of poly(styrene sulfonic acid) membranes for the transport of protons against bivalent cations (Zn 2+ and Cu 2+ ) by modifying these membranes with a thin layer of polyaniline. 24,25 It was also shown that the permselectivity behavior was linked to the location of the PANI layer within the membrane matrix.…”
Nafion membranes were modified by chemical polymerization of aniline using ammonium peroxodisulfate as the oxidant. The Nafion-polyaniline composite membranes were extensively characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and ion-exchange capacity measurements. The transport properties were also evaluated by conductivity and electrodialysis measurements. The data show that when a high oxidant concentration (1 M (NH4)2S2O8) is used, polyaniline is mostly formed at the surface of the Nafion membrane with a higher proportion of oligomers. On the contrary, when 0.1 M oxidant is used, polyaniline is mostly formed inside the ionic domains of Nafion, blocking the pathway to ion transport and thus reducing the transport of Zn2+ as well as the transport of H+. These data were also compared to the data obtained with poly(styrene sulfonate)-PANI composite membranes.
“…Recovery to metallic palladium occurs in the region of potentials from 0.6 to 0.25 V, and oxidation to Pd 2+ at the reverse of the potential to the anode side -from 0.6 to 0.9 V. Such a large potential difference, from 0.2 to 0.6 V, indicates that the recovered Pd 0 is on the working electrode in the form of adsorbed clusters. It should be noted that in this potential range, from 0.3 to 0.6 V, the PAN is in an electrically conductive state (in the form of emeraldine), which indicates that the polymer matrix provides conditions for charge transport [17,18].…”
Section: Features Of Obtaining a Polyaniline Electrode With Embedded ...mentioning
Results of the development of a method for immobilizing nanosized palladium into an electrochemically synthesized polyaniline (PAn) electrically conductive porous matrix to create a sensitive element of an ignition sensor are presented. Two methods of manufacturing a sensitive element in the form of an electrode are investigated. The first method consists in the co-precipitation of polyaniline and palladium on a graphitized butyl rubber substrate in a mode of cycling of potential. It was shown that this method can be used to obtain a volume-porous electrode in which palladium nanoparticles are embedded in a polyaniline matrix. The second method involves the deposition of palladium on a polyaniline film formed on graphitized butyl rubber. It was shown that micron-sized island palladium conglomerates on the surface of a polyaniline film can be obtained by this method. The conclusions made are confirmed by physical research methods and the results of scanning electron microscopy. Investigations of the electrocatalytic properties of the electrode in the sensor model showed that with a change in the H2 concentration formed upon ignition, occurs change in the hydrogen concentration on the surface of metal-catalyst (Pd) and a linear change in the current of electrochemical reaction. Comparison of a composite volume-porous polyaniline electrode with embedded palladium showed its superior efficiency compared to a compact palladium electrode and an electrode in which palladium is deposited on the surface of a polyaniline film. The possibility of using an electrochemical detector based on polyaniline with immobilized palladium nanoparticles for a gas amperometric sensor of low hydrogen concentrations and a fire hazard detector is shown.
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