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Chemisorption

About: Chemisorption is a research topic. Over the lifetime, 16298 publications have been published within this topic receiving 554989 citations.


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TL;DR: It is shown that hydrogen acts as an inhibitor for the CH(4) dehydrogenation on copper, contributing to suppress deposition onto the copper substrate, and degrades quality of graphene.
Abstract: Understanding the chemical vapor deposition (CVD) kinetics of graphene growth is important for advancing graphene processing and achieving better control of graphene thickness and properties. In the perspective of improving large area graphene quality, we have investigated in real-time the CVD kinetics using CH4–H2 precursors on both polycrystalline copper and nickel. We highlighted the role of hydrogen in differentiating the growth kinetics and thickness of graphene on copper and nickel. Specifically, the growth kinetics and mechanism is framed in the competitive dissociative chemisorption of H2 and dehydrogenating chemisorption of CH4, and in the competition of the in-diffusion of carbon and hydrogen, being hydrogen in-diffusion faster in copper than nickel, while carbon diffusion is faster in nickel than copper. It is shown that hydrogen acts as an inhibitor for the CH4 dehydrogenation on copper, contributing to suppress deposition onto the copper substrate, and degrades quality of graphene. Additionally, the evidence of the role of hydrogen in forming C–H out of plane defects in CVD graphene on Cu is also provided. Conversely, resurfacing recombination of hydrogen aids CH4 decomposition in the case of Ni. Understanding better and providing other elements to the kinetics of graphene growth is helpful to define the optimal CH4/H2 ratio, which ultimately can contribute to improve graphene layer thickness uniformity even on polycrystalline substrates.

417 citations

Journal ArticleDOI
TL;DR: In this article, a proposal is made about the nature of the metal/support interaction phenomena occurring in ceria-supported noble metal (NM/CeO2) catalysts as the reduction temperature is increased.

415 citations

Journal ArticleDOI
TL;DR: In this article, a two-dimensional precipitation from a dilute mixed fluid into a solid phase rather than a solid-solid transformation is described, which is more appropriately described to be of ''added-row'' rather than of ''missing-row''.
Abstract: Scanning tunneling microscopy investigations on nucleation and growth of the (2\ifmmode\times\else\texttimes\fi{}1)O-Cu(110) structure revealed that the new phase is formed by condensation of mobile chemisorbed O atoms with Cu adatoms evaporating from steps and diffusing across the terraces of the substrate surface. This process can be regarded as two-dimensional precipitation from a dilute mixed fluid into a solid phase rather than a solid-solid transformation. The resulting structure is more appropriately described to be of ``added-row'' rather than of ``missing-row'' type.

415 citations

Journal ArticleDOI
TL;DR: In this paper, the enhancement of CO sensitivity in the Al doped graphene is determined by a large electrical conductivity change after adsorption, where CO absorption leads to increase of electrical conductivities via introducing large amount of shallow acceptor states.

412 citations

Journal ArticleDOI
TL;DR: In this paper, the location of a half monolayer of ordered hydrogen adatoms on Ni(111) has been analyzed by Low-Energy Electron Diffraction (LEED), Thermal Desorption Spectroscopy (TDS), and Work Function (Δφ) measurements.
Abstract: The location of a half monolayer of ordered hydrogen adatoms on Ni(111) has been analyzed by Low‐Energy Electron Diffraction (LEED), Thermal Desorption Spectroscopy (TDS), and Work Function (Δφ) measurements. It is found that the hydrogen atoms are arranged in an overlayer of graphitic structure with a (2×2) unit cell with respect to the substrate unit cell. In the ordered regions, the hydrogen adatoms occupy both types of three fold hollow sites without a detectable difference in the Ni–H bond lengths between the two sites. The Ni–H bond length is found to be 1.84±0.06 A, corresponding to an overlayer‐substrate spacing of 1.15±0.1 A. The relation between this structure and its observed order–disorder phase diagram as a function of temperature and hydrogen coverage is discussed. The disorder is discussed in detail, and a novel ’’atomic band structure’’ interpretation is given.

410 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023567
20221,044
2021538
2020424
2019458
2018350