Studies On Electrocatilytic Activity Of Conducting Polymers/metal Composites

With the energy becoming less and less and the pollution of the environmentbecoming more and more serious, people are looking for new energy to add or replacethe normal energy. Direct fuel cells as new-style energy devices have attracted greatattention because of their high-energy conversion efficiency and low pollutant emission.Direct fuel cells belong to a new green energy that burn hydrogen, methanol and formicetc as fuels, which produce electricity by chemical action the mainly production is water.However, direct fuel cells have not been widespread used due to the high cost of Pt.Therefore, how to raise the utilization rate of Pt is the key. For example, to reduce thesize and increase the dispersity and homogeneity of Pt on the support surface. Catalystsupports are very important for improving the efficiency of catalysts. The most commonCps presently used as fuel cell catalyst supports are conjugated polymers withheteroatoms in the main chain (heterocyclic polymers) as polyaniline (PAni),polypyrrole (PPy), polythiophene (PTh) and their derivatives.In this paper, conducting polymer/noble metals composite catalysts have beenfabricated. As-prepared composite catalysts were characterized by SEM, EDX andelectrochemical methods，and the electro-catalytic activities of composite catalyststowards methanol and formic acid oxidation have been investigated.(1) A poly(o-methoxyaniline)(POMA) film has been prepared by a simplepotentiostatic electrodeposition method in sulfuric acid solution. Pt and its alloy Pt-M(M=Ru, Au, Pd) have also been successfully electrodeposited on the POMA films. Theresults of SEM show that POMA is a three-dimensional porous network structure, metalnanoparticles were dispersed uniformly on the POMA surface and the morphologies ofmetal nanoparticles were similar. The results showed that POMA and Pt-M bimetalmodified GC electrode improved significantly the catalytic activity of Pt nanoparticlesfor methanol electrooxidation. Additionally, the activity of methanol oxidation on thesecomposite electrodes followed the order: Pt-Ru/POMA/GC> Pt/POMA/GC> Pt-Au/POMA/GC> Pt/GC.(2) The Pt/POMA/GC electrode material was prepared under the same conditionand used for the electrooxidation of formic acid in acidic media. Compared with Pt/GC,Pt/POMA/GC had higher catalytic activity and stronger poisoning resistance. At thesame time, the effects of different parameters related to the formic oxidation reactionkinetics, such as Pt loading, thickness of POMA film, concentration of formic andpotential scan rate, have been investigated in detail. The results of the strippingvoltammograms of CO show that POMA can largely weaken the interference of CO oncatalysts and electro-oxidize COadseasily.(3) Poly(o-dihydroxybenzene)(PoDHB) films were synthesized by aelectrochemical polymerization of biphenyl in pure boron trifluoride diethyl etherate onglassy carbon electrode (GC). The Pt nanoparticles were dispersed onto PoDHB(Pt/PoDHB/GC) and the electro-catalytic activities towards formic acid and methanoloxidation have been investigated respectively. Compared with Pt/GC, Pt/PoDHB/GChad higher catalytic activity and stronger poisoning resistance. The improvedelectrocatalytic performance of Pt/PoDHB/GC may be attributed to the roughness of thePoDHB film and the synergistic effect between PoDHB and Pt nanoparticles. Factorssuch as platinum loading, polymer mass, methanol/formic acid concentration andH2SO4concentration influencing on the anodic current of electro-oxidation of methanoland formic acid on the Pt/PoDHB/GC electrode have been evaluated in detail.