著者

國貞 雄治

出版者

公益社団法人 日本表面真空学会

雑誌

表面と真空 (ISSN:24335835)

巻号頁・発行日

vol.65, no.11, pp.531, 2022-11-10 (Released:2022-11-10)

参考文献数

2

著者

長谷川 瞬 國貞 雄治 坂口 紀史

出版者

公益社団法人 日本表面真空学会

雑誌

表面と真空 (ISSN:24335835)

巻号頁・発行日

vol.63, no.8, pp.413-418, 2020-08-10 (Released:2020-08-10)

参考文献数

24

被引用文献数

1

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We investigated oxygen reduction reaction (ORR) activity of Pt single atoms and Pt sub-nano clusters (Pt1, Pt2 Pt3) on pristine and various light-element doped graphene using first-principles calculations based on density functional theory. We revealed that ORR activity of these systems shows so-called volcano plot with adsorption energy of an OH which is an ORR intermediate as well as bulk metal catalysts. Additionally, we note that ORR activity of Pt1 is higher than those of Pt2 and Pt3, and a support effect caused by light-elements doped graphene is more clearly observed in the cases of Pt1. Therefore, the combination of Pt1 and proper light-element doped graphene support is a promising candidate for designing a new catalyst that competes with the current fuel cell catalyst ; bulk Pt catalyst.

著者

國貞 雄治

出版者

公益社団法人 日本表面真空学会

雑誌

表面と真空 (ISSN:24335835)

巻号頁・発行日

vol.66, no.10, pp.572-573, 2023-10-10 (Released:2023-10-10)

参考文献数

2

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The division of Young Researchers was established in 2018. This division organizes interdisciplinary workshops in a format that facilitates learning for students and young researchers. In this special issue, the recent research achievements have been introduced by young researchers and lecturers at the previous workshop. The presented topics cover angle-resolved photoemission spectroscopy, water molecule networks on solid surfaces, simulation of laser processing of semiconductors, and in situ observation of electrode surfaces by high-speed atomic force electron microscopy. This special issue also contains an article on how to write a scientific paper.

著者

國貞 雄治

出版者

一般社団法人 日本真空学会

雑誌

Journal of the Vacuum Society of Japan (ISSN:18822398)

巻号頁・発行日

vol.60, no.7, pp.249-255, 2017 (Released:2017-07-15)

参考文献数

47

被引用文献数

2

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We theoretically investigated physisorption on ice Ih and ice XI surfaces, because the physisorption states of adsorbates play important roles in the chemical reaction on the interstellar medium, which generally consists of ice, with the extremely low temperature (10 K) condition. In this paper, we focused on hydrogen molecules as adsorbates because hydrogen is the most abundant element in space. At first, we briefly reviewed the way to treat the van der Waals interaction in density functional theory. We also showed the calculated adsorption states of hydrogen molecules on ice Ih and ice XI surfaces. We found the non-local correlation functional, which can treat the dispersion interaction, improved the potential energies of physisorbed hydrogen molecules on ice Ih and ice XI surfaces.

著者

國貞 雄治 坂口 紀史

出版者

公益社団法人 日本金属学会

雑誌

日本金属学会誌 (ISSN:00214876)

巻号頁・発行日

vol.80, no.9, pp.570-574, 2016 (Released:2016-08-25)

参考文献数

24

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We have investigated trapping effects of monoatomic vacancies Vmono and alloy atoms on hydrogen diffusion at Al(111) surfaces. We performed first-principles calculations based on density functional theory with generalized gradient approximation in order to obtain the hydrogen adsorption energies in the vicinity of monoatomic vacancies and alloy atoms in Al(111) subsurfaces. We considered Si, Cr, Mn, Fe, Cu, Ge, and Zn as alloy atoms. We substituted one Al atom with one monoatomic vacancy or alloy atom, which corresponds to Al0.95X0.05(111) (X=Si, Cr, Mn, Fe, Cu, Ge, Zn, Vmono) surfaces. We found that all of monoatomic vacancies and alloy atoms increase adsorption energies. We also clarified that hydrogen atoms make strong covalent bonds in Cr, Mn, Fe-alloyed Al(111) subsurfaces, while they make only weak ionic bonds in pure and Si, Cu, Ge, Zn-alloyed Al(111) subsurfaces.

著者

國貞 雄治

出版者

公益社団法人 日本表面真空学会

雑誌

表面と真空 (ISSN:24335835)

巻号頁・発行日

vol.62, no.4, pp.229, 2019-04-10 (Released:2019-04-10)

著者

長谷川 瞬 國貞 雄治 坂口 紀史

出版者

公益社団法人 日本表面真空学会

雑誌

表面と真空 (ISSN:24335835)

巻号頁・発行日

vol.62, no.6, pp.344-349, 2019-06-10 (Released:2019-06-10)

参考文献数

23

被引用文献数

1

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We investigated the adsorption states and diffusion behavior of Pt and Fe atoms on pristine and various light-element-doped graphene using first-principle calculations based on density functional theory to reveal the support that can keep particle size of metal clusters for a long time. We show a weak interaction between Pt, Fe atoms and pristine graphene. The corresponding diffusion barrier for a Pt atom on pristine graphene is only 0.14 eV, which causes rapid agglomeration of Pt clusters. However, light-element-doped graphene shows large diffusion barrier for metal atoms. Notably, O, Si and P doped graphene show large diffusion barrier for both Pt and Fe atoms. Therefore, these light-element-doped graphene is a promising support for Pt and Fe clusters.