Pdn-Fe纳米合金作为Mg-H2O2半燃料电池阴极研究

摘要

Carbon-supported palladium-iron composite electrocatalysts with different Pd to Fe atom ratios (2 :1, 4 :1, 8 :1) were prepared by a chemical reduction method. The morphology and surface state of the Pdn-Fe/C and Pd/C electrocatalysts were characterized by X-ray diffractionanalysis (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicated that Fe was added to the Pd/C catalyst and reacted with Pd to form Pdn-Fe alloy, with slightly varied particle size. And the Pdn-Fe catalyst particles were homogeneously distributed on the surface of the C carrier with the average particle size between 2-3 nm. The addi-tion of Fe influenced crystal lattice structure of Pd/C catalysts. Electrochemical (CV, LSV, CA) data showed that the eletrocatalytic activity of the Pd4-Fe/C electrocatalyst for hydrogen peroxide electroreduction was much higher than that of Pd/C. The current density of Pd/C electrode for hydrogen peroxide electroreduction reaction was 17.71 mA/cm2 whenE = 0.2 V and the current density of Pd4-Fe/C electrode was up to 19.42 mA/cm2. The Mg-H2O2 semi-fuel cell performance text showed that both the open circuit potential of the two fuel cells were about 1.8 V, of which the power density of Mg-H2O2semi-fuel cell using Pdn-Fe/C as the cathode was higher 41 mW/cm2 than that using Pd/C as cathode.%通过化学还原方法制备Pd:Fe原子比(n)为2:1、4:1、8:1的Pdn-Fe/C催化剂.采用TEM、XRD和XPS技术对复合催化剂进行表征.结果显示,Fe加入Pd/C催化剂中,与Pd形成合金,Pdn-Fe/C催化剂的粒径发生变化;获得的Pd4-Fe纳米合金粒子在C载体表面分布均匀,平均粒径为2～3 nm,Fe的加入对Pd/C催化剂晶体结构有很大影响.电化学(CV,LSV,CA)测试表明:加入Fe提高了Pd/C催化剂的催化性能,Pd/Fe原子比为4:1时,Pdn-Fe/C的催化性能最好.当E=0.2 V时,Pd/C电极电流密度为17.71 mA/cm2,而Pd4-Fe/C电极电流密度可达19.42 mA/cm2.电池测试表明,以Pd4-Fe/C和Pd/C催化剂为阴极的Mg-H2O2半燃料电池的开路电势均为1.8 V左右,而当电流密度为180 mA/cm2时,以Pd4-Fe/C为阴极的电池最大能量密度比Pd/C为阴极的电池高41 mW/cm2.