title: Pt3Ti nanoparticles: fine dispersion on SiO2 supports, enhanced catalytic CO oxidation, and chemical stability at elevated temperatures.
abstract: A platinum-based intermetallic phase with an early d-metal, Pt(3)Ti, has been synthesized in the form of nanoparticles (NPs) dispersed on silica (SiO(2)) supports. The organometallic Pt and Ti precursors, Pt(1,5-cyclooctadiene)Cl(2) and TiCl(4)(tetrahydrofuran)(2), were mixed with SiO(2) and reduced by sodium naphthalide in tetrahydrofuran. Stoichiometric Pt(3)Ti NPs with an average particle size of 2.5 nm were formed on SiO(2) (particle size: 20-200 nm) with an atomically disordered FCC-type structure (Fm3m; a = 0.39 nm). A high dispersivity of Pt(3)Ti NPs was achieved by adding excessive amounts of SiO(2) relative to the Pt precursor. A 50-fold excess of SiO(2) resulted in finely dispersed, SiO(2)-supported Pt(3)Ti NPs that contained 0.5 wt % Pt. The SiO(2)-supported Pt(3)Ti NPs showed a lower onset temperature of catalysis by 75 degrees C toward the oxidation reaction of CO than did SiO(2)-supported pure Pt NPs with the same particle size and Pt fraction, 0.5 wt %. The SiO(2)-supported Pt(3)Ti NPs also showed higher CO conversion than SiO(2)-supported pure Pt NPs even containing a 2-fold higher weight fraction of Pt. The SiO(2)-supported Pt(3)Ti NPs retained their stoichiometric composition after catalytic oxidation of CO at elevated temperatures, 325 degrees C. Pt(3)Ti NPs show promise as a catalytic center of purification catalysts for automobile exhaust due to their high catalytic activity toward CO oxidation with a low content of precious metals.
authors.affiliation: National Institute for Materials Science, Sengen 1-2-1, Tsukuba, Ibaragi 305-0047, Japan. SARAVANAN.Govindachetty@nims.go.jp
authors.forename: Govindachetty
authors.initials: G
authors.lastname: Saravanan
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
authors.forename: Ya
authors.initials: Y
authors.lastname: Xu
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Sekido
authors.forename: Hirohito
authors.initials: H
authors.lastname: Hirata
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamabe-Mitarai