Single Crytalline Noble Metal Ultrathin-Film-Like Nanoparticle Formed in Adsorbed Micelle Film as Reaction Filed Formed at Solid-Liquid Interface, and Production Method Thereof

Abstract

It is aimed at creating noble metal nanoparticles having novel shapes, sizes, and arrangements usable for catalysts, electrodes, and the like. Micelles made into rod-like shapes having semicylindrical cross-sections are formed on a carrier substrate in a self-creating manner and immobilized thereon; noble metal ions are added and diffused in the micelles to complex the micelles with noble metal ions; and a reducing agent is subsequently caused to act thereon to progress a reductive reaction of noble metal within the immobilized micelles as reaction fields, thereby growing single crystalline noble metal ultrathin-film nanoparticles on the carrier substrate by utilizing the fixed micelles having the shapes as templates, respectively.

1 . A single crystalline noble metal ultrathin-film determinate-form nanoparticle characterized in that the single crystalline noble metal ultrathin-film determinate-form nanoparticle is produced in a solid-liquid interface two-dimensional micelle acting as a reaction field and formed of one kind or two kinds of surfactants on a carrier substrate;
 that the single crystalline noble metal ultrathin-film determinate-form nanoparticle is constituted of at least one kind of noble metal selected from a group consisting of platinum (Pt), gold (Au), silver (Ag), palladium (Pd), rhodium (Rh), iridium (Ir), and ruthenium (Ru); and   that the single crystalline noble metal ultrathin-film determinate-form nanoparticle exhibits an ultrathin film shape having a thickness in a range of 2 to 5 nm, and has an arbitrary contour selected from a shape of disk, rod, plate, and sheet.   
     
     
         2 . The single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 1 , characterized in that the carrier substrate is any one of graphite, mica, and silica. 
     
     
         3 . The single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 1 , characterized in that means for producing the noble metal nanoparticle in the micelle is provided by a reductive reaction conducted within the micelle as the reaction field. 
     
     
         4 . The single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 3 , characterized in that the reductive reaction is achieved by hydrazine. 
     
     
         5 . The single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 1 , characterized in that the noble metal nanoparticle is picked up in a state carried by the carrier, by picking up the carrier substrate after the reductive reaction followed by drying. 
     
     
         6 . The single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 5 , characterized in that the noble metal particle picked up in the state carried on the carrier is collected by separating the noble metal particle from the carrier substrate. 
     
     
         7 . The single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 1 , characterized in that the noble metal is platinum. 
     
     
         8 . A production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle, characterized in that the method comprises the steps of:
 preparing a micelle forming solution containing one kind or two kinds of surfactants at a micelle concentration;   subsequently immersing a carrier substrate into the micelle forming solution, to cause a micelle formed in a rod-like shape having a semicircle cross-section to be formed on and immobilized to the carrier substrate;   subsequently adding a solution containing a noble metal ion into the micelle to thereby contain the noble metal ion within the micelle; and   subsequently causing a reducing agent to act on the micelle containing therein the metal ion to thereby progress a reductive reaction within the immobilized micelle as a reaction field, to produce a single crystalline noble metal ultrathin-film determinate-form nanoparticle exhibiting a thin-film shape having a thickness in a range of 2 to 5 nm and having an arbitrary contour selected from a shape of disk, rod, plate, and sheet, by utilizing the immobilized micelle as a template.   
     
     
         9 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of claim  8 , characterized in that the two-dimensional micelle as the reaction field is adjusted in shape and size, to thereby adjust a shape and a size of the produced noble metal ultrathin-film determinate-form nanoparticle. 
     
     
         10 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 8 , characterized in that the noble metal ion is one kind of ion selected from platinum (Pt), gold (Au), silver (Ag), palladium (Pd), rhodium (Rh), iridium (Ir), and ruthenium (Ru) ions. 
     
     
         11 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 8 , characterized in that the surfactant for forming the two-dimensional micelle comprises one kind or two kinds of surfactants so that the noble metal thinfilm-like particle is controlled in thickness, shape, and size, by changing the kind of the surfactant, or the kinds of the surfactants and a mixing ratio therebetween. 
     
     
         12 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 8 , characterized in that the noble metal ion within the micelle is changed in concentration, to control the single crystalline platinum thinfilm-like particle in thickness, size, and the like. 
     
     
         13 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 8 , characterized in that the carrier is one kind of carrier selected from graphite, mica, and silica. 
     
     
         14 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 8 , characterized in that the reductive reaction is achieved by hydrazine. 
     
     
         15 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 8 , characterized in that the noble metal nanoparticle exhibits a single two-dimensional film shape grown to have one side dimension of 50 nm or more. 
     
     
         16 . The production method of a single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 8 , characterized in that noble metal is platinum. 
     
     
         17 . A noble metal catalyst material, characterized in that the noble metal catalyst material includes the single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 1 , to be used as an active ingredient in catalyst design. 
     
     
         18 . The noble metal catalyst material of  claim 17 , characterized in that the noble metal catalyst material is used in catalyst design for fuel cell. 
     
     
         19 . The noble metal catalyst material of  claim 17 , characterized in that the noble metal catalyst material is used for designing a vehicular exhaust gas purifying catalyst. 
     
     
         20 . A noble metal electrode material, characterized in that the noble metal electrode material includes the single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 1 , to be used as an electrode designing material for cell or electrolysis. 
     
     
         21 . A noble metal sensor material, characterized in that the noble metal sensor material includes the single crystalline noble metal ultrathin-film determinate-form nanoparticle of  claim 1 , to be used as a sensor designing material.