Ni2P@CoP3核壳纳米球的制备、表征及其用于超级电容器性能

利用水热技术先后获得Ni纳米球和Ni@Co(OH)_2海胆状核壳纳米球前驱体,通过高温煅烧法获得NiO@CoO核壳纳米球,再以次磷酸钠为原料,通过高温磷化法最终获得Ni_2P@CoP_3核壳纳米球。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高角度环形暗场像扫描透射电子显微镜(HAADF-STEM)、X射线粉末衍射仪(XRD)、能谱仪(EDS)及X射线光电子能谱(XPS)对产物的形貌、结构和组成进行表征。采用循环伏安(CV)、恒电流充放电(GCD)以及循环稳定性实验探索了电极材料的电化学性能。结果表明,Ni_2P@CoP_3核壳纳米球的直径约为400 nm,由六方系Ni_2P纳米核和立方相CoP_3纳米壳构成。相比单纯的Ni_2P或CoP_3纳米球,Ni_2P@CoP_3核壳纳米球发挥了复合结构的协同效应,更加有利于电解液的质子传递,促进了赝电容反应,表现出更高的比容量、稳定性和更长的循环寿命。

Synthesis and Characterization of Ni2P@CoP3 Core-Shell Nanospheres for Supercapacitors

Ni nanospheres and Ni@Co(OH)₂ nano-urchin-spheres precursor were successively fabricated with hydrothermal technique, and then the latter were changed into NiO@CoO by high temperature calcination process, and Ni₂P@CoP₃ core-shell nanospheres were finally obtained using sodium hypophoshpite as raw material by high temperature phosphating process. The morphologies, structures and compositions of the as-obtained products were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), high angle annular dark field-scanning transmission electron microscope (HAADF-STEM), X-ray powder diffractometer (XRD), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). At the same time, the electrochemical performance of the electrodes were investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and cycling stability experiments. The results showed that as-obtained Ni₂P@CoP₃ core-shell nanospheres with diameter of~400 nm were composed of hexagonal Ni₂P nanocore and cubic CoP₃ nanoshell. Compared with pure Ni₂P or CoP₃ nanospheres, Ni₂P@CoP₃ core-shell nanospheres are more conducive to the mass transfer of electrolyte and promote the pseudo capacitive reaction because of its synergistic effect of composite structure, which shows higher specific capacity, stability and longer cycle life.