11:15 〜 11:30
▲ [19a-W834-9] Electronic structural study of Pd-Pt bimetallic alloy nanoparticles
キーワード：Bimetallic nanoparticles,Electronic structures,Catalyst
Bimetallic nanoparticles (NPs) have attracted much attention due to their potential applications in numerous fields of science and technology. Pd-Pt bimetallic NPs as significant systems play an important role as effective catalysts. The hydrogen storage capacity of PdxPt1-x solid alloy NPs can be tuned by changing the composition of Pd and Pt. And it also had a higher hydrogen-storage capacity than the core/shell type NPs. Hydrogen absorption properties of metal NPs are strongly correlated with the structure and the electronic state. Therefore, to know the electronic structures of Pd-Pt alloy NPs will be helpful to understand their high activity and selectivity properties as a catalyst. The bulk electronic structures of materials can be reliably probed using hard x-ray photoelectron spectroscopy (HAXPES), which provides a long effective information depth about 15 ~ 17 nm in Pt and Pd. This value is greater than the diameter of the largest NPs. Hence, we were able to obtain information regarding the electronic structures of the NPs. XPS measurement shows two peaks at Pd 3d5/2 for Pd NPs and Pd-Pt alloy NPs. The Pd 3d5/2 binding energy of Pd0 (Pd metal atoms) is 335.0 eV and Pd/C (from carbon modified phase) is 335.6 eV. The valence band spectrum of alloy NPs was not reproduced by linear combination of Pd and Pt NPs. This difference was suggested possible unoccupied state near Fermi-edge. The capacity of hydrogen-storage of Pd-Pt alloy NPs probably correlated with the unoccupied state of d band metal. The core-levels and valence band electronic structures of Pd-Pt bimetallic alloy NPs are provide useful information of catalytic properties, to gain further development of high-efficient nanosized materials.