直接乙醇燃料电池PtSn/C电催化剂的合成表征和性能

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

采用多元醇法制备了 n( Pt) /n( Sn)比为 2∶ 1 ,3∶ 1 ,4∶ 1的 Pt Sn/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 Pt Sn/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 ;Pt Sn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Pt4 Sn/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 Pt Sn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 40 h寿命测试前后的阳极 Pt3Sn/C催化剂的分析 ( Energy dispersive X-rayanalysis,EDX)结果表明 ,Pt Sn含量在测试前后均有所降低 ,Pt

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.