title: Formation of Pt-Ru nanoparticles in ethylene glycol solution: an in situ X-ray absorption spectroscopy study.
abstract: The chemical state and formation mechanism of Pt-Ru nanoparticles (NPs) synthesized by using ethylene glycol (EG) as a reducing agent and their stability have been examined by in situ X-ray absorption spectroscopy (XAS) at the Pt LIII and Ru K edges. It appears that the reduction of Pt(IV) and Ru(III) precursor salts by EG is not a straightforward reaction but involves different intermediate steps. The pH control of the reaction mixture containing Pt(IV) and Ru(III) precursor salts in EG to 11 led to the reduction of Pt(IV) to Pt(II) corresponding to [PtCl4](2-) whereas Ru(III)Cl3 is changed to the [Ru(OH)6](3-) species. Refluxing the mixture containing [PtCl4](2-) and [Ru(OH)6](3-) species at 160 degrees C for 0.5 h produces Pt-Ru NPs as indicated by the presence of Pt and Ru in the first coordination shell of the respective metals. No change in XAS structural parameters is found when the reaction time is further increased, indicating that the Pt-Ru NPs formed are extremely stable and less prone to aggregation. XAS structural parameters suggest a Pt-rich core and a Ru-rich shell structure for the final Pt-Ru NPs. Due to the inherent advantages of the EG reduction method, the atomic distribution and alloying extent of Pt and Ru in the Pt-Ru NPs synthesized by the EG method are higher than those of the Pt-Ru/C NPs synthesized by a modified Watanabe method.
authors.affiliation: Nanoelectrochemistry Laboratory, Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan.
authors.forename: Loka Subramanyam
authors.initials: LS
authors.lastname: Sarma
authors.forename: Ching-Hsiang
authors.initials: CH
authors.lastname: Chen
authors.forename: Sakkarapalayam Murugesan Senthil
authors.initials: SM
authors.lastname: Kumar
authors.forename: Guo-Rung
authors.initials: GR
authors.lastname: Wang
authors.forename: Shih-Chieh
authors.initials: SC
authors.lastname: Yen
authors.forename: Din-Goa
authors.initials: DG
authors.lastname: Liu
authors.forename: Hwo-Shuenn
authors.initials: HS
authors.lastname: Sheu
authors.forename: Kuan-Li
authors.initials: KL
authors.lastname: Yu
authors.forename: Mau-Tsu
authors.initials: MT
authors.lastname: Tang
authors.forename: Jyh-Fu
authors.initials: JF
authors.lastname: Lee
authors.forename: Christina
authors.initials: C
authors.lastname: Bock
authors.forename: Kuei-Hsien
authors.initials: KH
authors.lastname: Chen
authors.forename: Bing-Joe
authors.initials: BJ
authors.lastname: Hwang