直接乙醇燃料电池PtSn/C电催化剂的合成表征和性能

采用多元醇法制备了n(Pt)/n(Sn)比为2:1,3:1,4:1的PtSn/C电催化剂.通过XRD,TEM、循环伏安和氢化学吸附技术对催化剂进行了表征.TEM和XRD结果表明,不同比例的PtSn/C金属粒子的平均粒径均小于4nm,且粒径分布较窄;该系列催化剂中Pt具有fcc结构;PtSn间的相互作用使Pt晶格参数增大.循环伏安和氢化学吸附实验结果表明,加入Sn可抑制Pt对氢的吸附,Pt3Sn/C对乙醇的氧化电流比Pt4Sn/C高约1倍.用不同n(Pt)/n(Sn)比的催化剂作为直接醇类燃料电池阳极电催化剂,在相同条件下,随着Sn含量的增加,单电池最大输出功率逐渐增大,当Sn含量继续增大时,单池性能反而下降.导致不同比例PtSn催化剂活性差别的原因可能是由于Sn与Pt间的合金化程度不同和催化剂粒子尺寸效应及Sn含量对电池阻抗等几方面因素所致.对40h寿命测试前后的阳极Pt3Sn/C催化剂的分析(EnergydispersiveX-rayanalysis,EDX)结果表明,PtSn含量在测试前后均有所降低,PtSn催化剂的寿命尚有待改善.

Synthesis, Characterization and Performance of PtSn/C Electrocatalyst for Direct Ethanol Fuel Cell

PtSn/C electrocatalysts(Pt 2Sn/C,Pt 3Sn/C,Pt 4Sn/C) with different n (Pt)/ n (Sn) ratios were prepared by a modified polyol process and characterized by XRD,TEM and cyclic voltammetry (CV) techniques. TEM results show that the mean size of metal particles in the catalysts prepared is smaller than \{4 nm\} with a sharp distribution. XRD results show that all the in-house catalysts have fcc crystalline structure. The crystal lattice parameter a fcc of Pt in Pt 3Sn/C is 0.394 6 nm,which implies that alloying of Pt and Sn could dilate the cell lattice parameter of Pt. CV and H 2 chemisorption results show that the unit activity of PtSn/C increased. CV results also show that Pt 3Sn/C has the highest activity for ethanol oxidation. Single cell tests with PtSn/C as the anode catalysts show that maximum output power increased with increasing Sn molar fraction,and then decreased. The difference of catalytic activity between PtSn/C with various Sn molar fractions may be caused by the particle size effect,alloying degree between Pt and Sn and the cell internal impedance. The EDX analyses of the Pt 3Sn/C catalyst before and after stabilization test show that the content of both Pt and Sn decreased. The life of PtSn/C catalysts needs to be improved further.