碳纳米管表面修饰程度对其载Pd纳米粒子的电催化氧化水合肼性能的影响

Effect of Modification Extent of Carbon Nanotubes on Electrocatalytic Performance of Pd Nanoparticles for Hydrazine Oxidation

比较了未氧化处理与经浓硝酸或混酸(浓硫酸与浓硝酸体积比为1∶1)处理后的不同多壁碳纳米管(MWNTs)为载体的Pd催化剂(Pd/MWNTs)对水合肼氧化的电催化性能.光谱表征和电化学测试结果表明,MWNTs表面不修饰或修饰程度过大都不利于金属Pd纳米粒子的沉积.浓硝酸处理使MWNTs表面修饰的含氧基团适中,能够促进负载的Pd纳米粒子均一分布,因此提高Pd/MWNTs催化剂对水合肼的电催化性能.相反,混酸处理使MWNTs表面产生的含氧基团过多,导致金属Pd纳米粒子部分聚集,从而降低Pd/MWNTs催化剂对水合肼的电催化性能.

Purified multi-walled carbon nanotubes（MWNTs） were treated with concentrated HNO3 or mixed acid [V（HNO3）∶V（H2SO4）=1∶1],respectively.When MWNTs were treated in concentrated HNO3 solution,suitable amount of hydrophilic O-containing surface groups would be formed.So the average size of the Pd nanoparticles deposited on the surface of the pretreated MWNTs is small and uniform,leading to the good electrocatalytic performance of the resulting Pd/MWNTs catalyst for the hydrazine electrooxida-tion.If purified MWNTs were untreated,the pristine surface of MWNTs prevented deposition of Pd nanoparticles on the surface of MWNTs,which lead to the aggregation of Pd nanoparticles.When MWNTs were treated in mix acid solution,the amount of the hydrophilic O-containing surface groups formed on MWNTs was abundant,which also resulted in the agglomeration of Pd nanoparticles.Consequently,the re-sulting Pd/MWNTs catalysts displayed the low electrocatalytic performance for the hydrazine electrooxida-tion.