三维多孔核壳结构PdNi@Au催化剂的制备及对甲酸的电催化氧化

以K₂PdCl₄/K₂Ni(CN)₄为前驱体制备了具有凝胶特性的氰胶(Cyanogels), 利用硼氢化钠还原氰胶得到三维多孔珊瑚状PdNi合金前驱体, 在此基础上通过原位Galvanic置换反应, 制备得到内核为PdNi合金、 表面具有不同厚度Au层的三维多孔PdNi@Au催化剂. X射线衍射(XRD)分析和透射电子显微镜(TEM)观测结果显示, 该三维网状结构由粒径约7 nm的纳米颗粒相互连接形成; 能量分散光谱(EDX)线性扫描和元素分布(Mapping)分析显示该催化剂具有典型的核壳结构. 电化学测试结果表明, 表面Au层的厚度影响PdNi@Au催化剂的性能, 当Au的含量(摩尔分数)为5.6%时, 催化剂显示出对甲酸最佳的电催化活性, 对甲酸电催化氧化的峰电流密度达到商业化铂黑催化剂的7.2倍.

Fabrication of 3D Porous Core-shell PdNi@Au Nanocatalyst for Formic Acid Electro-oxidation†

K₂PdCl₄ and K₂Ni(CN)₄ were employed as precursors to fabricate cyanogel, which was then reduced by NaBH₄ to prepare 3D porous coral-like PdNi alloy. On the basis of the synthesized PdNi alloy, 3D porous PdNi@Au catalysts with PdNi alloy as inner core and Au layers of different thickness on the surface were synthesized by in situ Galvanic replacement between PdNi alloy and HAuCl₄ aqueous solution. X-Ray diffraction(XRD) and transmission electron microscopy(TEM) indicated that the 3D network structure was composed of interconnected nanoparticles with diameter of 7 nm. Energy dispersive X-ray(EDX) line scanning and mapping could declare its typical core-shell structure. Electrochemical measurements demonstrated that the electro-catalytic performance of PdNi@Au catalysts could be affected by the thickness of Au layer. When the content of Au reached a value of 5.6%(molar fraction), PdNi@Au catalyst exhibited the best catalytic performance for formic acid electro-oxidation. In this case, the peak current density of PdNi@Au catalyst was 7.2 times that of commercial Pd black.