Pd-Ag/C@TiO2核壳结构纳米棒阵列的制备及对NaBH4电氧化的催化性能

摘要

通过热蒸发结合恒电位沉积法制备了具有核壳结构的Pd-Ag/C@TiO2催化剂.利用X射线衍射仪( XRD)、扫描电子显微镜( SEM)和透射电子显微镜( TEM)等对所制备样品的形貌和结构进行了表征,利用线性伏安扫描和计时电流技术研究了Pd-Ag/C@TiO2电极对NaBH4的电氧化性能.结果表明, Pd-Ag/C@TiO2电极具有三维纳米核壳结构,在电化学反应过程中有利于燃料与催化剂充分接触.催化剂中Pd与Ag的原子比为0.37：0.17的Pd-Ag(2：1)/C@TiO2催化剂的效果最佳,在3.0 mol/L NaOH+0.20 mol/L NaBH4溶液中电流密度达到672 mA/cm2,在1200 s测试时间内计时电流曲线衰减很小,说明该Pd-Ag/C@TiO2电极对NaBH4电氧化具有很高的电化学活性和稳定性.%Pd-Ag/C@TiO2 core/shell nanorods catalysts were prepared via a thermal evaporation method fol-lowed by constant potential electrodeposition. The catalysts were characterized by X-ray diffractometer( XRD) , scanning electron microscope( SEM) and transmission electron microscope( TEM) . The catalytic performance of the obtained electrodes for NaBH4 electrooxidation was evaluated by means of linear scan voltammetry and chronoamperometry. The results show that the as-prepared Pd-Ag/C@TiO2 electrode owns special three di-mensional(3D) core/shell structure, which is of benefit to the diffusion of the fuel and the contact between catalyst and fuel during the electrochemical reaction. The performance of Pd-Ag(2:1)/C@TiO2 core/shell nanorods with a Pd/Ag atomic ratio of around 0. 37:0. 17 is the best, of which a current density of 672 mA/cm2 in the solution containing 3. 0 mol/L NaOH+0. 20 mol/L NaBH4 was obtained. The chronoamperometric current densities remain nearly constant within a 1200 s test. The results indicate that Pd-Ag(2:1)/C@TiO2 core/shell nanorods has considerable electrochemical activity and stability for NaBH4 electrooxidation.