Study On Electrocatalyst In Direct Ethanol Fuel Cell

Direct ethanol fuel cell (DEFC) possesses low-temperature, start up quickly and high energy transfer efficiency, the abundant sources, cheap price, the safety for the storage and transportation of fuel. The potential application of DEFC for portable electric equipment, mobile telephone and electric car has a great importance for sovling scarcity of energy sources and environmental pollution. However, one of the most important problems is the low electrochemical activity of anodic catalysts. In addition, noble metal Pt with high price and seldom sources is still the primary catalysts for DEFC. Therefore, in order to reduce the cost of fuel cell, it is necessary for us to develope novel catalysts with low loading and high activity. In this paper, several studies has been done to solve this problem in DEFC, the main results in this paper are presented as follows:(1) The SiO₂ modified carbon nanotubes were prepared through sol-gel method and used as the catalyst support. The Pt/SiO₂-CNTs nanocatalyst was synthesized by microwave-assisted chemical reduction method. The micrograph and elemental composition of Pt/SiO₂-CNTs nanoparticles were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. The electrocatalytic properties of Pt/SiO₂-CNTs nanocatalysts for ethanol oxidation were investigated by cyclic voltammetry in acidic solution. Under the same catalyst loading mass and experimental conditions, Pt/SiO₂-CNTs nanocatalyst show higher electrocatalytic activity than PtRu/C (E-TEK) catalyst. Additionally, Pt/SiO₂-CNTs nanocatalyst possesses good anti-poisoning ability.(2) SiO₂ nanoparticles were carbonized by decompostition of ethyne at high temperature to abtain SiO₂-C and subsequently used as the support for the preparation of the Pt/SiO₂-C electrocatalyst. The micrograph of the SiO₂-C particles and the elemental composition of Pt-SiO₂-C electrocatalyst were characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. The electrocatalytic properties of Pt/SiO₂-C electrocatalyst for ethanol oxidation were investigated by cyclic voltammetry and eletrochemical impedance spectroscopy was used to test the conductivity of the Pt/SiO₂-C electrocatalyst. The results indicate that the Pt/SiO₂-C electrocatalyst shows higher catalytic activities and better conductivity. It also indicates that the conductivity of SiO₂ particles has been improved by carbonization treatment, which may be the reason for the high electrocatalystic performance of Pt/SiO₂-C electrocatalyst.(3) MnO_x-C composites were prepared by the reaction between KMnO4 and C6H12O6. The morpholog, composition and crystalline structure of the composite were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction, respectively. The electrocatalytic activity of MnO_x-C for oxygen reduction reaction (ORR) was investigated with cyclic voltammetry method in alkaline solution. The results indicate that MnO_x-C possesses high electrocatalytic activity for ORR, it would be a high efficiency, low cost cathode electrocatalyst in alkaline fuel cell.