Platinum and palladium films obtained by low-temperature MOCVD for the formation of small particles on divided supports as catalytic materials
Platinum and palladium films obtained by low-temperature MOCVD for the formation of small particles on divided supports as catalytic materials
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DOI：
10.1021/cm990406e
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发表时间：
2000-02-01
影响因子：
8.6
通讯作者：
Kalck, P
中科院分区：
文献类型：
--
作者：
Hierso, JC;Feurer, R;Kalck, P
致力于在微电子平面衬底上沉积铂和钯的CVD研究清楚地表明，在200摄氏度以上的温度下可以获得高质量的沉积物。在约100摄氏度甚至更低的温度下制备纯金属沉积物的尝试是普遍感兴趣的，因为然后可以利用许多温度敏感的载体。本文提出了催化剂制备领域中另一个引人注目的问题。选择Pt（hfa）（2）、PtMe 2（cod）、Pd（Cp）（eta（3）-C3 H5）和Pd（eta（3）-C3 H5）（hfa）通过MOCVD在平面和分开的载体上制备铂和钯沉积物。报道了前体络合物的EI-质谱以及它们的热行为（TGA、DSC、蒸气压方程），在载气中引入氢气导致络合物的沉积温度（35-120 ° C）急剧降低。XPS和电子微探针分析表明，PtMe 2（cod）、Pd（Cp）（eta（3）-C3 H5）和Pd（eta（3）-C3 H5）（hfa）是在这些非常低的温度下制备纯薄膜的合适前体。Pt（hfa）（2）的结果很差，因为沉积物被氟、氧和主要是碳污染。在减压条件下在流化床中使用CVD方法允许在多孔分开的基底上沉积金属。在非常温和的温度（低于120摄氏度）下可以制备在二氧化硅上的钯和铂的高度分散的金属颗粒。TEM显微照片显示纳米颗粒的窄尺寸分散（平均尺寸1-3 nm）。EDX分析未显示沉积物的任何污染。一个高的过饱和度制度被确定为流化床MOCVD方法中的一个关键参数，允许良好的成核速率相对于生长速率。用该方法制备的多孔二氧化硅负载钯、铂催化剂对环己烷脱氢反应具有较高的活性。
CVD studies devoted to platinum and palladium deposition on planar substrates for microelectronics have clearly shown that it is possible to reach high-quality deposits at temperatures above 200 degrees C. Attempts to prepare pure metallic deposits at temperatures around 100 degrees C and even lower are of general interest, since a number of temperature-sensitive supports could be then exploited. An other attracting issue in the field of catalysts elaboration is presented here. Pt(hfa)(2), PtMe2(cod), Pd(Cp)(eta(3)-C3H5), and Pd(eta(3)-C3H5)(hfa) have been selected to produce by MOCVD platinum and palladium deposits on planar and on divided supports. The EI-mass spectrometry of the precursor complexes as well as their thermal behavior are reported (TGA, DSC, vapor pressure equations), introduction of hydrogen in the carrier gas results in a dramatic decrease of the deposition temperature (35-120 degrees C) of the complexes. XPS and electron microprobe analyses have shown that PtMe2(cod), Pd(Cp)(eta(3)-C3H5), and Pd(eta(3)-C3H5)(hfa) are suitable precursors to produce pure thin films at these remarkably low temperatures. Pt(hfa)(2) gave poor results since the deposits are contaminated with fluorine, oxygen, and principally carbon. Using the CVD method in a fluidized bed under reduced pressure conditions allowed the deposition of the metals on porous divided substrates. Highly dispersed metallic particles of palladium and platinum on silica can be prepared under very mild temperatures (below 120 degrees C). TEM micrographies revealed a narrow size dispersion of the nanoparticles (average size 1-3 nm). EDX analyses did not show any contamination of the deposits. A high supersaturation regime was identified to be a crucial parameter in the fluidized bed-MOCVD method, allowing a good nucleation rate with regard to the growth rate. Catalysts prepared by this method, and containing palladium and platinum on porous silica, were highly active for the dehydrogenation of cyclohexane.