Synthesis of ultrasmall platinum nanoparticles and structural relaxation.
We report the synthesis of ligand-protected, ultrasmall Pt nanoparticles of ∼1 nm size via a one-phase wet chemical method. Using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), we determined the mass of the nanoparticles to be ∼8 kDa. Characterization of the Pt nanoparticles was further carried out by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), optical absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). Interestingly, we observed a large structural relaxation in the 8kDa nanoparticles (i.e. lattice parameter elongation by +10%) compared to bulk platinum. XPS analysis revealed a positive shift of Pt 4f core level energy by approximately +1 eV compared with bulk Pt, indicating charge transfer from Pt to S atom of the thiolate ligand on the particle. Compared to bulk Pt, the 5d band of Pt nanoparticles is narrower and shifts to higher binding energy. Overall, the ∼1 nm ultrasmall Pt nanoparticles exhibit quite distinct differences in electronic and structural properties compared to their larger counterparts and bulk Pt.
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA 15213, USA; State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, 2699 Qianjin Street, Changchun, Jilin 130012, China. Electronic address: anna.liuchao@gmail.com.
Chao
C
Liu
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA 15213, USA. Electronic address: gaoli@andrew.cmu.edu.
Gao
G
Li
National Energy Technology Laboratory (NETL), United States Department of Energy, Pittsburgh, PA 15236, USA. Electronic address: Douglas.Kauffman@CONTR.NETL.DOE.GOV.
Douglas R
DR
Kauffman
State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, Jilin University, 2699 Qianjin Street, Changchun, Jilin 130012, China. Electronic address: panggs@jlu.edu.cn.
Guangsheng
G
Pang
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA 15213, USA. Electronic address: rongchao@andrew.cmu.edu.
Rongchao
R
Jin
8kDa; Nanoclusters; Pt; Thiolate; Ultrasmall nanoparticles