脉冲微波辅助化学还原合成Pt/C 催化剂及其电催化氧还原性能

采用脉冲微波辅助化学还原法制备了质子交换膜燃料电池(PEMFC)用Pt/C 催化剂. 通过透射电镜(TEM)和X射线衍射(XRD)等分析技术对催化剂的微观结构和形貌进行了表征, 并利用循环伏安(CV)、线性扫描(LSV)和恒电位测量等方法评价了催化剂催化氧还原性能. 在此基础上制备了膜电极(MEA)并组装成单电池, 考察了制备的Pt/C 催化剂作为阴极催化剂材料的电催化性能. 结果表明, 脉冲微波辅助化学还原法是一种制备PEMFC催化剂的有效方法, 溶液pH值和微波功率对Pt 颗粒直径和分散有重要影响. TEM和XRD结果显示, 当溶液pH值为10 且微波功率为2 kW时, Pt 纳米粒子较均匀地分散在碳载体上, 粒径分布在1.3-2.4 nm之间, 平均粒径为1.8 nm. CV、LSV和恒电位测试结果表明, 该催化剂电化学比表面积(ESA)为55.6 m²·g^-1, 具有良好的催化氧还原反应活性和稳定性. 单电池测试结果表明, 在溶液pH值为10条件下, 微波功率为2 kW时制备的催化剂作阴极催化剂时, 单电池最高功率密度为2.26 W·cm^-2·mg^-1, 高于微波功率为1 kW时的最高功率密度(2.15 W·cm^-2·mg^-1)和Johnson Matthey催化剂的最高功率密度(1.89 W·cm^-2·mg^-1).

Pulse-Microwave Assisted Chemical Reduction Synthesis of Pt/C Catalyst and Its Electrocatalytic Oxygen Reduction Activity

We prepared a Pt/C catalyst for use in proton exchange membrane fuel cells(PEMFCs) by pulse-microwave assisted chemical reduction synthesis.The microstructure and morphology of the as-prepared catalyst was characterized by transmission electron microscopy(TEM) and X-ray diffraction(XRD).The catalyst’s electrocatalytic performance in the oxygen reduction reaction(ORR) was measured by cyclic voltammetry(CV),linear sweep voltammetry(LSV),and constant potential polarization.The results indicate that pulse-microwave assisted chemical reduction synthesis is an efficient method to prepare PEMFC catalysts and that the pH and the microwave power largely influence the size and dispersion of Pt nanoparticles.At pH 10 and at a microwave power of 2 kW,the Pt nanoparticles were found to be uniform in size and the Pt nanoparticles size ranged between 1.3 and 2.4 nm with an average size of 1.8 nm.Additionally,the Pt nanoparticles were found to be highly dispersed on the surface of the carbon support.The electrochemical measurements showed that the electrochemical surface area(ESA) of the catalyst was 55.6 m2·g-1 and the catalyst exhibited superior performance and stability in the ORR.The maximum power density of the single cell was 2.26 W·cm-2·mg-1 for the catalyst prepared at a microwave power of 2 kW and a pH of 10 as the cathode material.The maximum power density was higher than that of the catalyst prepared using a microwave power of 1 kW(2.15 W·cm-2·mg-1) and also higher than that of the catalyst from Johnson Matthey(1.89 W·cm-2·mg-1).