The valence band structure of AgxRh1–x alloy nanoparticles

Yang, Anli; Sakata, Osami; Kusada, Kohei; Yayama, Tomoe; Yoshikawa, Hideki; Ishimoto, Takayoshi; Koyama, Michihisa; Kobayashi, Hirokazu; Kitagawa, Hiroshi

doi:10.1063/1.4896857

Cited by 27 publications

(41 citation statements)

References 28 publications

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“…For all NPs, the main contribution to the total DOS in the VB region is from degenerated Rh 4 d states (cumulative effect of t 2 g and e g states39), because the photoionization cross-section of Rh 4 d at 6 keV is approximately 6 times that for Cu 3 d 40. The energies of Rh 4 d triplet structure A-C are consistent with previously reported experimental data as well as theoretical calculations41424344. In addition, reported VB data for larger monometallic Rh NPs (12.2 ± 1.6 nm) prepared in a similar manner qualitatively resemble the VB spectrum of bulk Rh41.…”

Section: Resultssupporting

confidence: 89%

Electronic Structure Evolution with Composition Alteration of RhxCuy Alloy Nanoparticles

Palina

Sakata

Kumara

et al. 2017

Sci Rep

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The change in electronic structure of extremely small RhxCuy alloy nanoparticles (NPs) with composition variation was investigated by core-level (CL) and valence-band (VB) hard X-ray photoelectron spectroscopy. A combination of CL and VB spectra analyses confirmed that intermetallic charge transfer occurs between Rh and Cu. This is an important compensation mechanism that helps to explain the relationship between the catalytic activity and composition of RhxCuy alloy NPs. For monometallic Rh and Rh-rich alloy (Rh0.77Cu0.23) NPs, the formation of Rh surface oxide with a non-integer oxidation state (Rh(3−δ)+) resulted in high catalytic activity. Conversely, for alloy NPs with comparable Rh:Cu ratio (Rh0.53Cu0.47 and Rh0.50Cu0.50), the decreased fraction of catalytically active Rh(3−δ)+ oxide is compensated by charge transfer from Cu to Rh. As a result, ensuring negligible change in the catalytic activities of the NPs with comparable Rh:Cu ratio to those of Rh-rich and monometallic Rh NPs.

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Section: Resultssupporting

confidence: 89%

Electronic Structure Evolution with Composition Alteration of RhxCuy Alloy Nanoparticles

Palina

Sakata

Kumara

et al. 2017

Sci Rep

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“…2 (f) and (g) (x ¼ 0.625 and 0.75) the cases with relatively high Ag, the DOS near E F is quite small. the Comparing the DOS's of Ag x Rh 1-x alloy with that of Pd, Ag 0.5 Rh 0.5 shows a high similarity especially at the Fermi edge vicinity as reported in the preceding work [18] while those of Ag 0.125 Rh 0.875 and Ag 0.875 Rh 0.125 are apparently different from that of Pd. We can see that the similarities of other intermediate compositions lie in between.…”

Section: Density Of Statessupporting

confidence: 67%

“…While the bottom edge of the band almost keep constant just under E-E F ¼ À6 eV, the top edge becomes lower with increasing the content of Ag. In the preceding study, the valence band structure of Ag 0.5 Rh 0.5 is carefully investigated on the basis of hard X-ray photoelectron spectroscopy measurements and DFT calculations [18]. The striking similarity of electronic structure of Ag 0.5 Rh 0.5 alloy with Pd in the E-E F range of 0 to À3.5 eV was found.…”

Section: Density Of Statesmentioning

confidence: 98%

“…The correlation between the H absorption property and the electronic structure is well discussed the former literature by Klein and Papaconstantopoulos et al [14e16] To understand the origin of Pd like property observed in AgeRh alloy systems, Seo et al theoretically studied the H absorption and electronic structure of the Ag 0.5 Rh 0.5 alloy using a super cell (layered) structure [17]. We also have studied the electronic structure of Ag 0.5 Rh 0.5 alloy both experimentally and theoretically to find the similarity between AgeRh alloys and Pd in the electronic states near the Fermi level [18]. As a next step to understand the unique properties of Ag 0.5 Rh 0.5 alloy, we theoretically investigated the hydrogen absorption properties in this study.…”

Section: Introductionmentioning

confidence: 97%

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Theoretical investigation of hydrogen absorption properties of rhodium–silver alloys

Yayama

Ishimoto

Koyama

2016

Journal of Alloys and Compounds

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a b s t r a c tThe density of states and the H absorption energy of Ag x Rh 1-x alloys were theoretically investigated by the first-principles method. The electronic structure of the alloys near the Fermi edge was similar to that of Pd, which is known as hydrogen-storage metal, and this indicated the electronic state at the part plays important role to determine the H absorption property. The results showed that the H absorption into the Ag x Rh 1-x alloys was thermodynamically stable and the trend of composition dependence agreed well with the experimental observation. Considering the atomic configuration of alloys, homogeneous structure is found to be a key in the emergence of H absorption nature in this alloy system.

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“…Surprisingly, we found that the Ag 0.5 Rh 0.5 solid-solution alloy was capable of absorbing hydrogen. The hard X-ray photoelectron spectroscopy (HAXPES) indicated that the electronic structures around the Fermi energy were very similar between Ag 0.5 Rh 0.5 alloy NPs and Pd NPs,[75] indicating that Ag 0.5 Rh 0.5 solid-solution NPs can be considered as ‘artificial Pd’. Such a result was also supported by first principles calculation.…”

Section: Solid-solution Type Pd–ru Npsmentioning

confidence: 99%

Recent progress in the structure control of Pd–Ru bimetallic nanomaterials

Kusada

Kitagawa

2016

Science and Technology of Advanced Materials

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Pd and Ru are two key elements of the platinum-group metals that are invaluable to areas such as catalysis and energy storage/transfer. To maximize the potential of the Pd and Ru elements, significant effort has been devoted to synthesizing Pd–Ru bimetallic materials. However, most of the reports dealing with this subject describe phase-separated structures such as near-surface alloys and physical mixtures of monometallic nanoparticles (NPs). Pd–Ru alloys with homogenous structure and arbitrary metallic ratio are highly desired for basic scientific research and commercial material design. In the past several years, with the development of nanoscience, Pd–Ru bimetallic alloys with different architectures including heterostructure, core-shell structure and solid-solution alloy were successfully synthesized. In particular, we have now reached the stage of being able to obtain Pd–Ru solid-solution alloy NPs over the whole composition range. These Pd–Ru bimetallic alloys are better catalysts than their parent metal NPs in many catalytic reactions, because the electronic structures of Pd and Ru are modified by alloying. In this review, we describe the recent development in the structure control of Pd–Ru bimetallic nanomaterials. Aiming for a better understanding of the synthesis strategies, some fundamental details including fabrication methods and formation mechanisms are discussed. We stress that the modification of electronic structure, originating from different nanoscale geometry and chemical composition, profoundly affects material properties. Finally, we discuss open issues in this field.

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The valence band structure of AgxRh1–x alloy nanoparticles

Cited by 27 publications

References 28 publications

Electronic Structure Evolution with Composition Alteration of RhxCuy Alloy Nanoparticles

Electronic Structure Evolution with Composition Alteration of RhxCuy Alloy Nanoparticles

Theoretical investigation of hydrogen absorption properties of rhodium–silver alloys

Recent progress in the structure control of Pd–Ru bimetallic nanomaterials

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