catalyst

1. Ptnanoparticles（Pt NPs） catalyst hydrogen storage media d ~ 1 - 102 nm electrodes for fuel cells Electron states of Pt atoms on the surface of Pt NPs are remarkable ! 195Pt NMR of Pt NPsdepends on ・molecular size ・chemisorbed molecules

2. Solid-state 195Pt NMR Peak positions of Pt compounds commercial Pt NPs a few MHz Pt complex bulk Pt （chemical shift） （Knight shift） The spins excited by conventional π/2 pulses （a few hundred kHz, at most） H2PtCl6 H2PtI6 (standard) [PtF6]2- 1.08 1.10 1.12 1.14 B0/ν0　（kG/MHz) Point-by-point plots of the peak area of the spin echoes on variable-field B0/ν0　（kG/MHz)

3. a home-built probe Instruments　（in Kyoto University) variable-field cryogen-free magnet controller PC amplifier OPENCORE NMR spectrometer[2][3]

4. 195Pt NMR of Pt NPs cubo-octahedral PtNPs bulk Pt (n = ∞) 195PtNMR of Pt NPs surface (n = 0) subsurface(n = 1) sub-subsurface （n = 2） K1 Kbulk K0 K2 B0/ν0　（kG/MHz)

5. The NMR layer model for Pt NPs the thickness of each Pt layer 0.23 nm phenomenological NMR layer model[4][5] healing length m×0.23 nm Kbulk: the Knight shift on bulk Pt metal K0: the Knight shift on the surface Pt atoms Kn: the Knight shift on the nth Pt layer n: layer number m: healing factor n×0.23 nm surface bulk moiety the additional effect of hybridization of 5d and 6s band core polarization by 5d conduction electron electron configuration of Pt atom: 6s25d8 →low 5d electron DOS at Fermi energy →high 5d electron DOS at Fermi energy

6. all d～ 2-3 nm 1.08 1.08 1.10 1.10 1.12 1.12 1.14 1.14 B0/ν0　（kG/MHz) B0/ν0　（kG/MHz) 195Pt NMRof Pt NPs protected by n-alkylthiols(1) C6 surface Pt-complex (H2Pt(OH)6) ? surface C10 Pt complex ?

7. C18 Pt complex ? 1.08 1.08 1.10 1.10 1.12 1.12 1.14 1.14 B0/ν0　（kG/MHz) B0/ν0　（kG/MHz) 195Pt NMRof Pt NPs protected by n-alkylthiols (2) surface C12 Pt-complex ? surface