scispace - formally typeset
Search or ask a question
Institution

Ulsan National Institute of Science and Technology

EducationUlsan, South Korea
About: Ulsan National Institute of Science and Technology is a education organization based out in Ulsan, South Korea. It is known for research contribution in the topics: Graphene & Catalysis. The organization has 5076 authors who have published 12081 publications receiving 352045 citations. The organization is also known as: Ulsan Gwahak Gisul Daehakgyo & UNIST.


Papers
More filters
Journal ArticleDOI
TL;DR: This Review describes how the tunable electronic structure of TMDs makes them attractive for a variety of applications, as well as electrically active materials in opto-electronics.
Abstract: Ultrathin two-dimensional nanosheets of layered transition metal dichalcogenides (TMDs) are fundamentally and technologically intriguing. In contrast to the graphene sheet, they are chemically versatile. Mono- or few-layered TMDs - obtained either through exfoliation of bulk materials or bottom-up syntheses - are direct-gap semiconductors whose bandgap energy, as well as carrier type (n- or p-type), varies between compounds depending on their composition, structure and dimensionality. In this Review, we describe how the tunable electronic structure of TMDs makes them attractive for a variety of applications. They have been investigated as chemically active electrocatalysts for hydrogen evolution and hydrosulfurization, as well as electrically active materials in opto-electronics. Their morphologies and properties are also useful for energy storage applications such as electrodes for Li-ion batteries and supercapacitors.

7,903 citations

Journal ArticleDOI
30 Jun 2017-Science
TL;DR: The introduction of additional iodide ions into the organic cation solution, which is used to form the perovskite layers through an intramolecular exchanging process, decreases the concentration of deep-level defects, enabling the fabrication of PSCs with a certified power conversion efficiency.
Abstract: The formation of a dense and uniform thin layer on the substrates is crucial for the fabrication of high-performance perovskite solar cells (PSCs) containing formamidinium with multiple cations and mixed halide anions. The concentration of defect states, which reduce a cell’s performance by decreasing the open-circuit voltage and short-circuit current density, needs to be as low as possible. We show that the introduction of additional iodide ions into the organic cation solution, which are used to form the perovskite layers through an intramolecular exchanging process, decreases the concentration of deep-level defects. The defect-engineered thin perovskite layers enable the fabrication of PSCs with a certified power conversion efficiency of 22.1% in small cells and 19.7% in 1-square-centimeter cells.

4,603 citations

Journal ArticleDOI
02 Jan 2015-Science
TL;DR: Graphene and related two-dimensional crystals and hybrid systems showcase several key properties that can address emerging energy needs, in particular for the ever growing market of portable and wearable energy conversion and storage devices.
Abstract: Graphene and related two-dimensional crystals and hybrid systems showcase several key properties that can address emerging energy needs, in particular for the ever growing market of portable and wearable energy conversion and storage devices. Graphene's flexibility, large surface area, and chemical stability, combined with its excellent electrical and thermal conductivity, make it promising as a catalyst in fuel and dye-sensitized solar cells. Chemically functionalized graphene can also improve storage and diffusion of ionic species and electric charge in batteries and supercapacitors. Two-dimensional crystals provide optoelectronic and photocatalytic properties complementing those of graphene, enabling the realization of ultrathin-film photovoltaic devices or systems for hydrogen production. Here, we review the use of graphene and related materials for energy conversion and storage, outlining the roadmap for future applications.

2,850 citations

Journal ArticleDOI
Kazunori Akiyama, Antxon Alberdi1, Walter Alef2, Keiichi Asada3  +403 moreInstitutions (82)
TL;DR: In this article, the Event Horizon Telescope was used to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87.
Abstract: When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 +/- 3 mu as, which is circular and encompasses a central depression in brightness with a flux ratio greater than or similar to 10: 1. The emission ring is recovered using different calibration and imaging schemes, with its diameter and width remaining stable over four different observations carried out in different days. Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M = (6.5 +/- 0.7) x 10(9) M-circle dot. Our radio-wave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible.

2,589 citations

Journal ArticleDOI
TL;DR: The Review will consider some of the current scientific issues underpinning lithium batteries and electric double-layer capacitors.
Abstract: Energy-storage technologies, including electrical double-layer capacitors and rechargeable batteries, have attracted significant attention for applications in portable electronic devices, electric vehicles, bulk electricity storage at power stations, and “load leveling” of renewable sources, such as solar energy and wind power. Transforming lithium batteries and electric double-layer capacitors requires a step change in the science underpinning these devices, including the discovery of new materials, new electrochemistry, and an increased understanding of the processes on which the devices depend. The Review will consider some of the current scientific issues underpinning lithium batteries and electric double-layer capacitors.

2,412 citations


Authors

Showing all 5153 results

NameH-indexPapersCitations
Yi Cui2201015199725
Rodney S. Ruoff164666194902
Liming Dai14178182937
Thomas P. Russell141101280055
Philipp E. Scherer13252274300
Jacob N. Israelachvili12652079786
Meilin Liu11782752603
Kian Ping Loh10466158406
Jaephil Cho9835836280
Kwang S. Kim9764262053
Roeland J. M. Nolte9067232527
Bongsoo Kim8969826907
Jae Sung Lee8440524369
Steve Granick8135323192
Zhongping Chen8174224249
Network Information
Related Institutions (5)
Nanyang Technological University
112.8K papers, 3.2M citations

94% related

University of Science and Technology of China
101K papers, 2.4M citations

93% related

École Polytechnique Fédérale de Lausanne
98.2K papers, 4.3M citations

93% related

Georgia Institute of Technology
119K papers, 4.6M citations

92% related

Chinese Academy of Sciences
634.8K papers, 14.8M citations

92% related

Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202365
2022145
20211,571
20201,617
20191,484
20181,381