电沉积铂铋纳米颗粒在甲酸电化学氧化中的催化性能

Electrodeposited PtBi Nanoparticles for Electrocatalytic Oxidation of Formic Acid

在直接甲酸燃料电池的研究中,催化剂的选择、制备和性能研究依然是探索的重点。虽然PtBi合金已被报道用于甲酸的电化学催化氧化且具有良好的催化性能,但由于这些物理或化学制备方法耗时而且烦琐的操作,探索更加简便的制备方法已经成为一种必要。采用恒电势沉积手段在玻碳电极上制备了均匀分散的球形PtBi纳米颗粒,PtBi纳米颗粒的平均直径为(63±20)nm,Pt∶Bi的原子比为1.18,非常接近于溶液中[PtCl6]2-∶Bi3+的摩尔比(1.11),表明恒电势电沉积适于作为一种简单而有效的方法用于制备粒径较为均匀、符合预定化学成分的PtBi纳米颗粒。采用循环伏安法和计时安培法考察了该催化剂对甲酸电化学氧化的催化性能。结果显示,在0.5 mol·L-1H2SO4溶液中,甲酸在PtBi纳米颗粒所修饰电极上的氧化起始电势较之在PtRu纳米颗粒所修饰电极上的氧化起始电势至少负移了200 mV;在1.0 mol·L-1NaOH溶液中,PtBi和PtRu纳米颗粒上的起始电势之差更扩大到了大约400 mV。而且,无论是在酸性还是碱性溶液中,PtBi纳米颗粒上的甲酸电氧化具有更高的电流密度。实验结果表明,所制备的PtBi纳米颗粒都展现了较PtRu纳米颗粒更高的催化活性。

In the studies of direct formic acid fuel cells,the choice,preparation and performance of catalysts are still at the central position.PtBi alloy was used as the catalyst for formic acid electrooxidation and showed good performance.However,neither physical melting nor chemical reduction was convenient to fabrication and electrochemical characterization because of their fussy and time-consuming operations.It was necessary to explore new and simple preparation methods.In the present work,well-distributed spherical PtBi nanoparticles were deposited on glassy carbon surface by a potentiostatic technique.The average size of PtBi nanoparticles was（63±20） nm in diameter.The atomic ratio of Pt to Bi（1.18） was close to the molar ratio of 2-to Bi3＋ ions in electrolyte（1.11）.These results proved that potentiostatic electrodeposition could act as a simple and effective method to produce spherical PtBi nanoparticles with uniform size and preset chemical composition.Their catalytic performances toward formic acid electrooxidation were studied with cyclic voltammetry and chronoamperometry.The experimental results showed that,in 0.5 mol · L-1 H2SO4 solution,the onset potential for formic acid electrooxidation at PtBi nanoparticles was more negative than that at PtRu nanoparticles by at least 200 mV.In 1.0 mol · L-1 NaOH solution,the difference between the onset potentials for formic acid electrooxidation at PtBi nanoparticles and at PtRu nanoparticles was about 400 mV.Besides,either in acid media or in alkaline media,the formic acid electrooxidation had higher current on PtBi nanoparticles than on PtRu nanoparticles.All these results displayed that PtBi nanoparticles had better catalytic activities toward formic acid electrooxidation than PtRu nanoparticles.