钴-聚吡咯-碳载PtNi燃料电池催化剂的制备及应用

采用脉冲微波辅助化学还原合成新型载体钴-聚吡咯-碳(Co-PPy-C)负载PtNi催化剂.利用透射电镜(TEM)和X射线衍射(XRD)研究了催化剂的结构和形貌,此外,利用循环伏安(CV)和线性扫描伏安(LSV)等方法测试了催化剂的电化学活性及耐久性. PtNi/Co-PPy-C催化剂的金属颗粒直径约为1.77 nm,催化剂在载体上分布均匀且粒径分布范围较窄. XRD结果显示, PtNi/Co-PPy-C中Pt(111)峰最强, Pt主要是面心立方晶格.CV结果显示,其电化学活性面积(ECSA)为72.5 m²·g^-1,明显高于商用催化剂Pt/C(JM)的56.9 m²·g^-1.为进一步考查催化剂耐久性,电化学加速5000圈耐久性测试后, PtNi/Co-PPy-C颗粒发生明显集聚, ECSA衰减率和0.9 V下比质量活性衰减率分别为38.2%和63.9%.此外,采用有效面积为50 cm²的单电池用于评价自制催化剂的性能,发现在70 ℃且背压为50 kPa时电池的性能最好,此时自制PtNi/Co-PPy-C催化剂制备膜电极(MEA)的最大功率密度达到523 mW·cm^-2.可见自制催化剂的电化学性能高于商用Pt/C(JM),在质子交换膜燃料电池(PEMFC)领域有一定的应用前景.

Preparation and Application of Pt-Ni Catalysts supported on Cobalt-Polypyrrole-Carbon for Fuel Cells

By using pulse-microwave assisted chemical reduction, we prepared a Pt-Ni alloy supported on a cobalt-polypyrrole-carbon (Co-PPy-C) catalyst. The catalyst microstructure and morphology were characterized by using transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrocatalytic performance and durability of the catalysts were measured with cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The metal particles were well dispersed on the carbon support, and the particle size of PtNi/Co-PPy-C was about 1.77 nm. XRD showed that the Pt(111) diffraction peak was strongest, so the most of the Pt in the catalysts was in a face-centered cubic lattice. The electrochemical surface area (ECSA) of PtNi/Co-PPy-C (72.5 m²·g^-1) was higher than that of Pt/C(JM) (56.9 m²·g^-1). After an accelerated durability test for 5000 cycles, the particle size of PtNi/Co-PPy-C obviously increased. The degradation rate of ECSA and the mass activity (MA) of PtNi/Co-PPY-C were 38.2% and 63.9%, respectively. We applied the PtNi/Co-PPy-C catalyst after optimizing the membrane electrode assembly (MEA) with an area of 50 cm². The fuel cell could be suitably operated at 70 ℃ with a back pressure of 50 kPa. At these conditions, the maximum power density of MEA by PtNi/Co-PPy-C was 523 mW·cm^-2. The excellent performance of PtNi/Co-PPy-C makes it a promising catalyst for proton exchange membrane fuel cells (PEMFCs).