非晶态合金纳米管的制备及其催化性能研究进展

Progress of the Study on the Synthesis and Catalytic Property of Noncrystalline Alloy Nanotubes

在Tween系列非离子/阴离子混合型表面活性剂与过渡金属盐所形成的溶致液晶体系中加入NaBH4,制备了过渡金属(M)与B的非晶态合金纳米管M-B(M=Fe,Co,Ni);制备时若在含Ni盐溶液中添加第三种组分(可为P,Co或Cu的化合物),则还可得到相应的NiPB,NiCoB或NiCuB三元非晶态合金纳米管.讨论了这类反应的机制,指出层状液晶相模板的存在是获得纳米管的关键,层中过渡金属离子被NaBH4还原的同时析出H2,导致层状液晶相解离并卷曲形成纳米管.在这一基础上通过微调实验条件并添加适当的稳定剂,可得到稳定的二元或三元过渡金属非晶态合金纳米管,并可在一定范围内调控其管径.在某些加氢反应中,非晶态纳米管具有比相应的非晶态纳米颗粒更好的催化性能,而且管径小的纳米管的催化性能比管径大的更好.由于非晶具有与结晶材料迥异的特性,非晶态合金纳米管可能具有独特的性能和应用前景.

Binary noncrystalline alloy nanotubes M-B （M=Fe,Co,and Ni） were prepared using NaBH4 as the reducing agent for the reduction of transition metal ions located in the layer structure of lytropic liquid crystals of mixed nonionic-anionic surfactants.By adding P-,Co-,or Cu-containing compound during the preparation of Ni alloy samples,ternary noncrystalline alloy nanotube,i.e.,NiPB,NiCuB,or NiCoB,can be obtained.It has been argued that the presence of the lytropic liquid crystals is the key for the formation of noncrystalline nanotubes.The reduction of transition metal ions located in the layer structure of the liquid crystal accompanied by the formation of H2 results in the cleavage and curl of the layer structure leading to the formation of nanotubes.The catalytic properties of some hydrogenation reactions have shown that the noncrystalline nanotubes are superior to the corresponding noncrystalline nanoparticles.Due to the well known unique properties of the noncrystalline materials,it is expected that the noncrystalline nanotubes,as a new type of nanotubes,might possess exciting prospects for their future application.