碳纳米管负载的Pd-Ag-Sn催化剂对甲酸的电氧化

摘要

米用硼氢化钠还原的方法合成了碳纳米管负载的钯基纳米催化剂(Pd/CNT,Pd7Ag3/CNT,Pd7Sn2/CNT,Pd7Ag1Sn2/CNT,Pd7Ag2Sn2/CNT和Pd7Ag3Sn2/CNT).通过XRD,TEM和XPS对其进行了表征,结果表明,相比Pd/CNT和Pd-Ag(或Pd-Sn)催化剂的纳米颗粒,Pd-Ag-Sn催化剂展现出了更小的平均颗粒尺寸(2.3 nm).此外,还通过循环伏安(CV)和计时电流法(CA)测试了这些催化剂对甲酸氧化的电活性,在酸碱介质中,Pd-Ag-Sn/CNT对甲酸氧化都表现出了更高的电流密度.其中,Pd7Ag2Sn2/CNT催化剂在酸碱介质中的电流密度分别是108.8和211.3 mA·cm-2,相应的Pd质量电流密度高达1 364和2 640 mA·mg-1,远远高于商业Pd/C,表明Pd-Ag-Sn/CNT催化剂对甲酸氧化表现出了极好的电催化活性.%Carbon nanotube-supported Pd-based binary and ternary nanocatalysts (Pd/CNT,Pd7Ag3/CNT,Pd7Sn2/ CNT,Pd7Ag1Sn2/CNT,Pd7Ag2Sn2/CNT and Pd7Ag3Sn2/CNT) have been fabricated by the NaBH4 reduction method.They have been characterized by using XRD,TEM and XPS techniques.The ternary Pd-Ag-Sn nanoparticles exhibit a smaller average particle size of ca.2.3 nm compared to Pd/CNT and binary Pd-Ag (or Pd-Sn) nanoparticles.The electrocatalytic activity of these catalysts towards formic acid oxidation in both H2SO4 and NaOH solutions has been investigated using cyclic voltammetry (CV) and chronoamperometry (CA).In both acidic and alkaline media,the ternary Pd-Ag-Sn/CNT catalysts present higher anodic current density for formic acid oxidation than Pd/CNT and binary PdAg/CNT or PdSn/CNT catalysts.Among the prepared catalysts,the Pd7Ag2Sn2/CNT catalyst displays the highest HCOOH oxidation current density of 108.8 mA·cm-2 in 0.5 mol·L-1 H2SO4 solution or 211.3 mA·cm-2 in 1 mol·L-1 NaOH solution,corresponding to the Pd mass current density of 1 364 or 2 640 mA·mg-1,respectively.These currents are extremely larger than those obtained from the commercial Pd/C.Results exhibit the excellent electrocatalytic activity of the ternary Pd7Ag2Sn2/CNT catalyst towards formic acid oxidation.