直接甲醇燃料电池阳极催化剂的新体系:纳米TiO_2-CNT-PtNi复合纳米催化剂

Novel System of Direct Methanol Fuel Cell Anode Catalysts: NanoTiO_2-CNT-PtNi Complex Catalysts

采用电合成前驱体Ti(OEt)_4直接水解法和电化学扫描电沉积法制备纳米TiO_2-CNT-PtNi复合纳米催化剂.透射电镜(TEM)和X射线衍射(XRD)测试结果表明,纳米PtNi合金粒子(平均粒径8nm)均匀地分散在纳米TiO2-CNT复合膜的三维网络结构中.通过暂态电化学方法研究表明,复合纳米催化剂的电化学活性比表面积为90m^2/g,对甲醇氧化具有很高的电催化活性和稳定性,常温常压下甲醇氧化峰电位为0.67和0.44V,当温度为60℃时,氧化峰电位负移至0.64和0.30V,氧化峰电流密度高达1.38A/cm^2.复合纳米催化剂对甲醇电氧化的高催化活性和稳定性可归因于多元复合纳米组分的协同催化作用,这种作用导致CO在复合纳米催化剂上的弱吸附,从而避免了催化剂的中毒.

The nanoTiO2-CNT-PtNi complex catalysts were prepared by the direct hydrolysis of electrosynthetic precursor Ti（OEt）4 and electrochemical scan electrodepositing method. The results of XRD and SEM show that the PtNi nanoparticle of average size 8 nm was dispersed uniformly on nanoTiO2-CNT complex film surface. The electrocatalytic activity of the nanoTiO2-CNT-PtNi complex catalysts was investigated by cyclic voltammetry and chronopotentiogram. The results indicated that the nanoTiO2-CNT-PtNi complex catalysts with Pt loading of 0.32 mg/cm^2 exhibited high electrochemically active surface area of 90 m^2/g and very high electrocatalytic activity and stability for electro-oxidation of methanol. The oxidation peak potential of methanol was 0.67 and 0.44 V at room temperature in atmosphere pressure, respectively, and shifted to 0.64 and 0.30 V at 60 ℃ and the oxidation peak current of methanol was 1.38 A/cm^2. The high electrocatalytic activity and good stability can be attributed to the synergistic catalytic effect of nanocomposite, which leads to the weak adsorption of CO on complex nanostructure catalysts, avoiding poisoning of the catalysts.