一步法制备纳米铂/石墨烯及电催化甲醇的交流阻抗和扩散系数测定

Nano-Pt/Graphene: One Step Synthesis and Characterization by AC Impedance and Diffusion Coefficient for Electrocatalysis of Methanol

采用绿色还原剂抗坏血酸,一步法制备纳米铂/石墨烯。对其进行X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)形貌结构表征,铂纳米粒子均匀分散于纳米石墨烯片层褶皱间,有效减少了团聚现象。运用循环伏安法(CV)和计时电流法(CA)研究纳米铂/石墨烯对甲醇电催化氧化活性和稳定性,通过交流阻抗(EIS)定量测定,发现铂/石墨烯比铂具有更优异的电荷传输性能,电荷转移阻抗下降了34.8%。计时电量法(CC)测定得到甲醇在铂/石墨烯电极的表面扩散系数为1.42×10^(-9) cm^2·s^(-1)。与铂纳米粒子相比,纳米铂/石墨烯对甲醇电催化氧化具有更高的活性和稳定性,显著提高电极催化活性表面积和电荷传输及转移性能。

Nano-Pt/graphene was prepared by adopting ascorbic acid as environmentally friendly reductant in one-step process. The morphology and structure of the products were characterized by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscope （TEM）. The results indicate that Pt nanoparticles are well dispersed in the wrinkled graphene nanosheets, which effectively prevents the aggregation of Pt nanoparticles. The eleetrocatalytic activity and stability of the catalysts for methanol oxidation were investigated by cyclic voltammetry （CV） and chronoamperometry （CA）. AC impedance （EIS） shows that nano-Pt/graphene has superior charge transport properties than Pt nanopartieles, leading to the decrease of transfer resistance by 34.8%. Furthermore, the diffusion coefficient of methanol on Pt-G/GC is 1.42×10^-9 cm2.s-1 by chronocoulometry （CC）. The results show that the nano-Pt/graphene has higher electrocatalytic activity and stability for methanol oxidation than Pt nanoparticles, which could significantly increase the catalytic active surface area of the electrode and accelerate charge transport and transfer performance.