碳载体预处理对纳米Pt/C电催化性能影响

利用NaBH₄还原机制,采用经不同方法预处理的碳载体成功制备出Pt/C-HNO₃、Pt/C-H₂O₂和Pt/C 3种碳载铂纳米催化剂.通过扫描电镜(SEM)、透射电镜(HR-TEM)、循环伏安(CV)和CO_ad溶出技术进行表征.结果表明,所制备的催化剂大小分布较为均一,平均粒径约为4 nm;HR-TEM观察发现,Pt/C-HNO₃中铂纳米粒子的表面具有较高的台阶原子密度;在CO_ad溶出实验中Pt/C-HNO_3­表现出较强的抗一氧化碳毒化能力;所制备的3种催化剂及商业催化剂Pt/C JM对乙醇氧化的电催化活性顺序为:Pt/C-HNO₃ > Pt/C-H₂O₂ > Pt/C > Pt/C JM,其中Pt/C-HNO₃的电催化活性和稳定性分别为Pt/C JM的1.5倍和1.9倍.

Effect of pretreatment of carbon support on electrocatalytic properties of Pt/C nanocatalysts

Carbon supported Pt nanocatalysts (Pt/C) are widely used in fuel cells. In this work, three kinds of Pt/C catalysts were successfully prepared via a chemical reduction method by using carbon black pretreated with different methods, i.e., HNO₃-pretreated carbon (Pt/C-HNO₃), H₂O₂-pretreated carbon (Pt/C-H₂O₂) and unpretreated carbon (Pt/C). The morphologies and properties of the as-prepared Pt/C catalysts were characterized by SEM, HR-TEM, CV and CO_ad stripping. Pt nanoparticles were dispersed well in these three Pt/C catalysts with average particle size of 3.4, 3.9 and 4.5 nm respectively. HR-TEM observation indicated that Pt/C-HNO₃ possessed high-density of step atoms and CO_ad stripping experiments showed that Pt/C-HNO₃ exhibited the best anti-poisoning property. Comparing the catalytic activities of three as-prepared Pt/C catalysts toward ethanol electrooxidation with commercial Pt/C catalyst (Pt/C JM) showed that the as-prepared catalysts exhibited higher activity and stability than those of Pt/C JM and the order was Pt/C-HNO₃>Pt/C-H₂O₂>Pt/C>Pt/C JM. Especially for Pt/C-HNO₃, its activity and stability were 1.5 times and 1.9 times of those of Pt/C JM respectively.