氮掺杂有序介孔碳-Ni纳米复合材料的制备及电化学性能

以F127为模板剂,Ni Cl2为镍源,尿素为氮源,间苯二酚甲醛原位聚合树脂为碳源,分别采用均相法和两相法制备Ni-NOMC-1,Ni-N-OMC-2纳米复合材料。X射线衍射(XRD)、激光拉曼以及透射电子显微镜(TEM)等测试结果表明,复合材料具有有序介孔结构,Ni以金属微粒形式嵌于碳骨架中,提高了有序介孔碳的石墨化程度。X射线光电子能谱测试(XPS)表明尿素热解后以4种形式存在:sp3杂化与C结合的N原子,吡啶N原子,sp2杂化与C结合的N原子以及quaternary-N原子。Ni-N的共改性改变了碳载体的理化性质,有利于Pt纳米粒子的负载与分散。均相法制备的Ni-N-OMC-1复合材料微波负载Pt后,氧还原极限电流密度为5.32 m A·cm-2,氢氧化电化学活性面积高达138.53 m2·g-1,电化学催化活性优于商业20%Pt/C材料(4.49 m A·cm-2,96.98 m2·g-1)。

Synthesis and Electrocatalytic Performance of N-Doped Ordered Mesoporous Carbon-Ni Nanocomposite

Highly ordered mesoporous carbon co-modified with Ni-Ncan be prepared via homogeneous phase route as well as dual-phase route, named as Ni-N-OMC-1 and Ni-N-OMC-2 respectively. Triblock copolymer Pluronic F127 were employed as the template agent, urea as the Nprecursor, NiCl₂ as the Ni source and resorcinol-formaldehyde resin as the carbon precursor. X-ray diffraction (XRD), Raman, and transmission electron microscope (TEM) showed that nickel particles dispersed in the carbon matrix in forms of metal nickel, in situ catalyzing the graphitization of amorphous carbon. X-ray photoelectron spectroscopy (XPS) revealed that urea existed in four different Nspecies after heat treatment: sp³ nitrogen atoms bonded to carbon atoms, pyridine-like N, sp³ nitrogen atoms bonded to carbon atoms and quaternary-Natoms. The co-modification of nitrogen and nickel changed the physicochemical properties of carbon matrix, thus making for the loading and dispersing of Pt. Pt nanoparticles deposited on Ni-N-OMC-1 nanocompsite showed excellent electrocatalytic activity. The electrochemical active surface area of hydrogen oxidation was 138.53 m²·g^-1 and the limiting current density in ORRwas 5.32 mA·cm^-2, which indicated higher electrocatalytic ability than that of the commercial 20% Pt/Ccatalysts (4.49 mA·cm^-2, 96.98 m²·g^-1).