Synthesis and Characterization of Novel Nanoporous Metals

以无孔二氧化硅纳米粒子为模板，采用模板法合成了具有91 m^2/g高比表面积的纳米多孔金属铂。模板化反应由四个步骤构成：1）Pt化合物在二氧化硅表面上的涂覆反应，2）Pt化合物的还原，3）通过碱处理溶解二氧化硅，和4）通过热处理去除纳米多孔铂中的残留碳。因此，通过相对方便的合成方法可以成功地获得由少量碳稳定的纳米多孔金属铂。该材料的电极使用玻璃碳作为基底制备：NanoPt/GC。NanoPt/GC对甲醇的电催化活性与市售铂黑电极相似，但对CO中毒有更强的抵抗力。将PVA膜浸泡在Pd（NO_3）_2水溶液中，通过超声处理使Pd离子浸渍到PVA膜的网络结构中。由于侧链上的羟基同时导致钯离子还原为金属钯，因此在该方法中不需要额外的还原过程。在N_2气氛中热处理去除含碳组分，但仍有大量碳残留。用SEM和XRD表征了Pd的粒径约为10 nm。为了去除这些含碳组分，应进行适度的氧化处理。

Nanoporous metallic platinum with a high specific surface area of 91 m^2/g was synthesized by a templating method using nonporous silica nanoparticles. The templating reaction is constituted of four steps : 1)a coating reaction of a Pt compound on the silica surface, 2)reduction of the Pt compound, 3)dissolution of the silica by alkaline treatment, and 4)removal of residual carbon in the nanoporous platinum by heat treatment. Thus, nanoporous metallic platinum, stabilized by a small amount of carbon, can successfully be obtained by a relatively convenient synthetic process. The electrode of this material were prepared using a glassy carbon as a substrate : NanoPt/GC. The electrocatalytic activity of NanoPt/GC shows a similar activity for methanol oxidation to that of the electrode using a commercial Pt black, and stronger resistivity againt a CO poisoning effect.Nanoparticles of metallic palladium surrounded by carbonaceous components were synthesized using a polyvinyl alcohol(PVA) film. The PVA film was immersed in Pd(NO_3)_2 aqueous solution and Pd ions were impregnated into the network structure of PVA film by sonication. Since the hydroxyl group on the side chain causes reduction of palladium ions to metallic palladium simultaneously, the additional reduction process is not needed in this process. The removal of carbonaceous components was tried by heat treatment in N_2 atmosphere but much content of carbon resided. The particle size of Pd is about 10 nm, which is characterized by SEM and XRD. The moderate oxidation treatment should be applied for removal of such carbonaceous components.