摘要
Annealing crystallization of ultrafine NiB amorphous alloy prepared by the chemical reduction method was studied by DTA, XRD and XAFS techniques. The XRD and XAFS results have revealed that the crystallization process of ultrafine NiB amorphous alloy proceeds in two steps. First, ultrafine NiB amorphous alloy is crystallized to form metastable nanocrystalline Ni3B at an annealing temperature of 325℃. Second, the nanocrystalline Ni3B is further decomposed into crystalline Ni at 380CCC or higher tempera ture, the local structure around Ni atoms in resultant product is similar to that in Ni foil. It was found that the catalytic activity of nanocrystalline Ni3B for benzene hydro-genation is much higher than that of ultrafine NiB amorphous alloy or crystalline Ni. The result indicates that the active sites of nanocrystalline Ni3B for benzene hydrogena-tion are composed of both Ni and B with proper geometry configuration.
Annealing crystallization of ultrafine NiB amorphous alloy prepared by the chemical reduction method was studied by DTA, XRD and XAFS techniques. The XRD and XAFS results have revealed that the crystallization process of ultrafine NiB amorphous alloy proceeds in two steps. First, ultrafine NiB amorphous alloy is crystallized to form metastable nanocrystalline Ni3B at an annealing temperature of 325°C. Second, the nanocrystalline Ni3B is further decomposed into crystalline Ni at 380°C or higher temperature, the local structure around Ni atoms in resultant product is similar to that in Ni foil. It was found that the catalytic activity of nanocrystalline Ni3B for benzene hydrogenation is much higher than that of ultrafine NiB amorphous alloy or crystalline Ni. The result indicates that the active sites of nanocrystalline Ni3B for benzene hydrogenation are composed of both Ni and B with proper geometry configuration.
基金
the National NaturalScience Foundation of China (Grant No. 29673038) and "the One-hundred People Plan" of the Chinese Academy of Sciences.
