多孔碳纳米纤维负载Pd纳米颗粒用于增强电催化氧还原性能

采用溶剂热法合成了以锆为金属核心、2-氨基为配体的锆基金属有机骨架（UiO-66）纳米材料，通过静电纺丝技术制备出UiO-66自由分散的聚丙烯腈（PAN/UiO-66）纤维，可控热解得到多孔碳纳米纤维（porous carbon nanofibers，PCNFs），结合湿化学还原法在PCNFs表面沉积Pd纳米颗粒，得到PCNFs@Pd复合材料。通过扫描电子显微镜、透射电子显微镜、X射线衍射技术对其形貌、组成、结构进行表征；采用电化学工作站分别测试了PCNFs@Pd在0.1 mol·L^-1 KOH和0.1 mol·L^-1 HClO₄电解质中氧还原性能（oxygen reduction reaction，ORR）。结果表明，在PAN纤维中添加UiO-66显著提高了PCNFs@Pd（Pd负载量为0.34%）复合材料的ORR性能。相比40% Pt/C，在碱性电解质中，PCNFs@Pd复合材料展示出更低的Tafel斜率、更优异的循环稳定性和耐甲醇中毒性。在酸性电解质中也表现出类似20% Pt/C的催化活性和循环稳定性。

Pd Nanoparticles Anchored on Porous Carbon Nanofibers for Enhanced Electrocatalytic Oxygen Reduction Reaction

Zirconium-based metal-organic frameworks (UiO-66) nanomaterials with 2-amino terephthalic acid as a ligand was synthesized by the solvothermal method. PAN/UiO-66 fibers with free-dispersed UiO-66 nanoparticles were prepared by electrospinning. Porous carbon nanofibers (PCNFs) were prepared by controllable pyrolysis. Pd nanoparticles were deposited on the surface of PCNFs by the wet-chemistry reduction method to obtain PCNFs@Pd composites. The morphologies, compositions, and structures of PCNFs@Pd were characterized by scanning electron microscope, transmission electron microscope, and X-ray diffraction. The performances of oxygen reduction reaction (ORR) of PCNFs@Pd were tested by electrochemical workstations in 0.1 mol·L^-1 KOH and 0.1 mol·L^-1 HClO₄ electrolytes, respectively. It was found that adding UiO-66 into PAN fibers significantly improved the ORR performance of PCNFs@Pd (0.34% of Pd loading) composites. Compared with 40%Pt/C, PCNFs@Pd composites in alkaline electrolytes showed lower Tafel slope, better cycle stability, and methanol toxicity resistance. Moreover, the catalytic activity and cycle stability of PCNFs@Pd were comparable to that of 20%Pt/C in acidic electrolytes.