Synthesis and Characterization of Novel Nanoporous Metals

采用模板法制备了比表面积高达91m^2/g的纳米多孔金属铂。模板反应由四个步骤组成：1)铂化合物在二氧化硅表面的包覆反应，2)铂化合物的还原，3)通过碱处理溶解二氧化硅，以及4)通过热处理去除纳米孔铂中的残余碳。因此，可以通过相对方便的合成工艺成功地获得由少量碳稳定的纳米多孔金属铂。该材料的电极是以玻碳为衬底制备的：纳米铂/GC。纳米铂/炭电极对甲醇氧化的电催化活性与商品铂黑电极相近，且对CO中毒有更强的抵抗能力。将PVA膜浸泡在Pd(NO3)2水溶液中，通过超声波将Pd离子浸渍到PVA膜的网络结构中。由于侧链上的羟基导致钯离子同时还原为金属钯，因此在此过程中不需要额外的还原过程。在氮气气氛下进行热处理，脱除了含碳成分，但残留了大量的碳。用扫描电子显微镜和X射线衍射仪对Pd进行了表征，结果表明，Pd的粒径约为10 nm。对于此类含碳成分的脱除，应采用中等氧化处理。

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.