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Holey graphene

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https://www.readbyqxmd.com/read/30525431/double-holey-heterostructure-frameworks-enable-fast-stable-and-simultaneous-ultrahigh-gravimetric-areal-and-volumetric-lithium-storage
#1
Zhonghui Chen, Jiadong Chen, Fanxing Bu, Phillips O Agboola, Imran Shakir, Yuxi Xu
Deliberate design of advantageous nanostructures holds great promise for developing high-performance electrode materials for electrochemical energy storage. However, it remains a tremendous challenge to simultaneously gain high gravimetric, areal, and volumetric capacities as well as high rate performance and cyclability to meet practical requirements mainly due to the intractable insufficient ion diffusion and limited active sites for dense electrodes with high areal mass loadings. Herein we report a double-holey-heterostructure framework, in which holey Fe2O3 nanosheets (H-Fe2O3) are tightly and conformably grown on the holey reduced graphene oxide (H-RGO)...
December 10, 2018: ACS Nano
https://www.readbyqxmd.com/read/30387317/sphere-to-multipod-transmorphic-change-of-nanoconfined-pt-electrocatalyst-during-oxygen-reduction-reaction
#2
Juchan Yang, Dongwoo Kang, Yuju Jeon, Jong Hoon Lee, Hu Young Jeong, Hyeon Suk Shin, Hyun-Kon Song
An oxygen reduction reaction (ORR) catalyst/support system is designed to have Pt nanoparticles nanoconfined in a nanodimensionally limited space. Holey crumpled reduced graphene oxide plates (hCR-rGO) are used as a carbon support for Pt loading. As expected from interparticular Pt-to-Pt distance of Pt-loaded hCR-rGO longer than that of Pt/C (Pt-loaded carbon black as a practical Pt catalyst), the durability of ORR electroactivity along cycles is improved by replacing the widely used carbon black with hCR-rGO...
November 2, 2018: Small
https://www.readbyqxmd.com/read/30356956/modified-mxene-holey-graphene-films-for-advanced-supercapacitor-electrodes-with-superior-energy-storage
#3
Zhimin Fan, Youshan Wang, Zhimin Xie, Duola Wang, Yin Yuan, Hongjun Kang, Benlong Su, Zhongjun Cheng, Yuyan Liu
MXene films are attractive for advanced supercapacitor electrodes requiring high volumetric energy density due to their high redox capacitance combined with extremely high packing density. However, the self-restacking of MXene flakes unavoidably decreases the volumetric performance, mass loading, and rate capability. Herein, a simple strategy is developed to prepare a flexible and free-standing modified MXene/holey graphene film by filtration of the alkalized MXene and holey graphene oxide dispersions, followed by a mild annealing treatment...
October 2018: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
https://www.readbyqxmd.com/read/30221261/high-energy-flexible-quasi-solid-state-lithium-ion-capacitors-enabled-by-a-freestanding-rgo-encapsulated-fe-3-o-4-nanocube-anode-and-a-holey-rgo-film-cathode
#4
Tian Liang, Huanwen Wang, Dongming Xu, Ke Liao, Rui Wang, Beibei He, Yansheng Gong, Chunjie Yan
Flexible energy storage devices have become critical components for next-generation portable electronics. In the present work, a flexible quasi-solid-state lithium-ion capacitor (LIC) is developed based on graphene-based bendable freestanding films in a gel polymer electrolyte. A graphene encapsulated Fe3O4 nanocube hybrid film (rGO@Fe3O4) has been fabricated as the anode of LICs through a filtration assisted self-assembly and the subsequent thermal annealing process. In this hybrid architecture, flexible and ultrathin graphene shells uniformly enwrap the Fe3O4 within the whole film, which can effectively suppress the aggregation of Fe3O4 and also accommodate the volume change of Fe3O4 during the cycling process...
September 27, 2018: Nanoscale
https://www.readbyqxmd.com/read/30067260/c-2-n-graphene-supported-single-atom-catalysts-for-co-2-electrochemical-reduction-reaction-mechanistic-insight-and-catalyst-screening
#5
Xudong Cui, Wei An, Xiaoyang Liu, Hao Wang, Yong Men, Jinguo Wang
Single-atom catalysts (SACs) have emerged as an excellent platform for enhancing catalytic performance. Inspired by the recent experimental synthesis of nitrogenated holey 2D graphene (C2N-h2D) (Mahmood et al., Nat. Commun., 2015, 6, 6486-6493), we report density functional theory calculations combined with computational hydrogen electrode model to show that C2N-h2D supported metal single atoms (M@C2N) are promising electrocatalysts for CO2 reduction reaction (CO2 RR). M confined at pyridinic N6 cavity promotes activation of inert O[double bond, length as m-dash]C[double bond, length as m-dash]O bonds and subsequent protonation steps, with *COOH → *CO → CHO predicted to be the primary pathway for producing methanol and methane...
August 16, 2018: Nanoscale
https://www.readbyqxmd.com/read/30017701/a-simple-and-robust-procedure-for-preparing-graphene-oxide-cryo-em-grids
#6
Eugene Palovcak, Feng Wang, Shawn Q Zheng, Zanlin Yu, Sam Li, Miguel Betegon, David Bulkley, David A Agard, Yifan Cheng
Graphene oxide (GO) sheets have been used successfully as a supporting substrate film in several recent cryogenic electron-microscopy (cryo-EM) studies of challenging biological macromolecules. However, difficulties in preparing GO-covered holey carbon EM grids have limited their widespread use. Here, we report a simple and robust method for covering holey carbon EM grids with GO sheets and demonstrate that these grids can be used for high-resolution single particle cryo-EM. GO substrates adhere macromolecules, allowing cryo-EM grid preparation with lower specimen concentrations and provide partial protection from the air-water interface...
October 2018: Journal of Structural Biology
https://www.readbyqxmd.com/read/29882370/nano-ruo-2-decorated-holey-graphene-composite-fibers-for-micro-supercapacitors-with-ultrahigh-energy-density
#7
Shengli Zhai, Chaojun Wang, Huseyin Enis Karahan, Yanqing Wang, Xuncai Chen, Xiao Sui, Qianwei Huang, Xiaozhou Liao, Xin Wang, Yuan Chen
Compactness and versatility of fiber-based micro-supercapacitors (FMSCs) make them promising for emerging wearable electronic devices as energy storage solutions. But, increasing the energy storage capacity of microscale fiber electrodes, while retaining their high power density, remains a significant challenge. Here, this issue is addressed by incorporating ultrahigh mass loading of ruthenium oxide (RuO2 ) nanoparticles (up to 42.5 wt%) uniformly on nanocarbon-based microfibers composed largely of holey reduced graphene oxide (HrGO) with a lower amount of single-walled carbon nanotubes as nanospacers...
June 7, 2018: Small
https://www.readbyqxmd.com/read/29863683/using-graphene-liquid-cell-transmission-electron-microscopy-to-study-in-situ-nanocrystal-etching
#8
Matthew R Hauwiller, Justin C Ondry, A Paul Alivisatos
Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in liquid environments. This manuscript describes the process for making graphene liquid cells through the example of graphene liquid cell transmission electron microscopy (TEM) experiments of gold nanocrystal etching. The protocol for making graphene liquid cells involves coating gold, holey-carbon TEM grids with chemical vapor deposition graphene and then using those graphene-coated grids to encapsulate liquid between two graphene surfaces...
May 17, 2018: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/29695646/three-dimensional-nitrogen-and-sulfur-co-doped-holey-reduced-graphene-oxide-frameworks-anchored-with-moo-2-nanodots-for-advanced-rechargeable-lithium-ion-batteries
#9
Jie Pei, Hongbo Geng, Huixiang Ang, Lingling Zhang, Huaixin Wei, Xueqin Cao, Junwei Zheng, Hongwei Gu
In this manuscript, we synthesize a porous three-dimensional anode material consisting of molybdenum dioxide nanodots anchored on nitrogen (N)/sulfur (S) co-doped reduced graphene oxide (GO) (3D MoO2 /NP-NSG) through hydrothermal, lyophilization and thermal treatment. First, the NP-NSG is formed via hydrothermal treatment using graphene oxide, hydrogen peroxide (H2 O2 ), and thiourea as the co-dopant for N and S, followed by calcination of the N/S co-doped GO in the presence of ammonium molybdate tetrahydrate to obtain the 3D MoO2 /NP-NSG product...
July 20, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29389044/synergistically-active-nico-2-s-4-nanoparticles-coupled-with-holey-defect-graphene-hydrogel-for-high-performance-solid-state-supercapacitors
#10
Sintayehu Nibret Tiruneh, Bong Kyun Kang, Sung Hoon Kwag, YoungHun Lee, MinSeob Kim, Dae Ho Yoon
Nickel cobalt sulfide nanoparticles embedded in holey defect graphene hydrogel (HGH) that exhibit highly porous structures and uniform nickel cobalt sulfide nanoparticle sizes are successfully prepared by a facile solvothermal-hydrothermal method. As an electrode material for supercapacitors, the as-prepared NiCo2 S4 @HGH shows ultra-high specific capacitances of 1000 F g-1 and 800 F g-1 at 0.5 and 6 A g-1 , respectively, owing to the outstanding electrical conductivity of HGH and high specific capacitance of NiCo2 S4 ...
March 2, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29380891/extrusion-based-3d-printing-of-hierarchically-porous-advanced-battery-electrodes
#11
Steven D Lacey, Dylan J Kirsch, Yiju Li, Joseph T Morgenstern, Brady C Zarket, Yonggang Yao, Jiaqi Dai, Laurence Q Garcia, Boyang Liu, Tingting Gao, Shaomao Xu, Srinivasa R Raghavan, John W Connell, Yi Lin, Liangbing Hu
A highly porous 2D nanomaterial, holey graphene oxide (hGO), is synthesized directly from holey graphene powder and employed to create an aqueous 3D printable ink without the use of additives or binders. Stable dispersions of hydrophilic hGO sheets in water (≈100 mg mL-1 ) can be readily achieved. The shear-thinning behavior of the aqueous hGO ink enables extrusion-based printing of fine filaments into complex 3D architectures, such as stacked mesh structures, on arbitrary substrates. The freestanding 3D printed hGO meshes exhibit trimodal porosity: nanoscale (4-25 nm through-holes on hGO sheets), microscale (tens of micrometer-sized pores introduced by lyophilization), and macroscale (<500 µm square pores of the mesh design), which are advantageous for high-performance energy storage devices that rely on interfacial reactions to promote full active-site utilization...
March 2018: Advanced Materials
https://www.readbyqxmd.com/read/29355834/creation-of-nanosized-holes-in-graphene-planes-for-improvement-of-rate-capability-of-lithium-ion-batteries
#12
L G Bulusheva, S G Stolyarova, A L Chuvilin, Yu V Shubin, I P Asanov, A M Sorokin, M S Mel'gunov, Su Zhang, Yue Dong, Xiaohong Chen, Huaihe Song, A V Okotrub
Holes with an average size of 2-5 nm have been created in graphene layers by heating of graphite oxide (GO) in concentrated sulfuric acid followed by annealing in an argon flow. The hot mineral acid acts simultaneously as a defunctionalizing and etching agent, removing a part of oxygen-containing groups and lattice carbon atoms from the layers. Annealing of the holey reduced GO at 800 °C-1000 °C causes a decrease of the content of residual oxygen and the interlayer spacing thus producing thin compact stacks from holey graphene layers...
April 3, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29261299/two-dimensional-holey-nanoarchitectures-created-by-confined-self-assembly-of-nanoparticles-via-block-copolymers-from-synthesis-to-energy-storage-property
#13
Lele Peng, Zhiwei Fang, Jing Li, Lei Wang, Andrea M Bruck, Yue Zhu, Yiman Zhang, Kenneth J Takeuchi, Amy C Marschilok, Eric A Stach, Esther S Takeuchi, Guihua Yu
Advances in liquid-phase exfoliation and surfactant-directed anisotropic growth of two-dimensional (2D) nanosheets have enabled their rapid development. However, it remains challenging to develop assembly strategies that lead to the construction of 2D nanomaterials with well-defined geometry and functional nanoarchitectures that are tailored to specific applications. Here we report a facile self-assembly method leading to the controlled synthesis of 2D transition metal oxide (TMO) nanosheets containing a high density of holes...
January 23, 2018: ACS Nano
https://www.readbyqxmd.com/read/29181477/a-facile-synthesis-of-reduced-holey-graphene-oxide-for-supercapacitors
#14
Xinjun Hu, Dongchen Bai, Yiqi Wu, Songbo Chen, Yu Ma, Yue Lu, Yuanzhi Chao, Yongxiao Bai
Hydroxyl radicals (˙OH) generated from a UV/O3 solution reaction is used to efficiently etch graphene oxide nanosheets under moderate conditions. Reduced holey graphene oxide is directly used as a supercapacitor electrode material and exhibits high specific capacitance (224 F g-1 at a current density of 1 A g-1 ) and high volumetric capacitance (up to 206 F cm-3 ).
December 12, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29164704/holey-reduced-graphene-oxide-coupled-with-an-mo-2-n-mo-2-c-heterojunction-for-efficient-hydrogen-evolution
#15
Haijing Yan, Ying Xie, Yanqing Jiao, Aiping Wu, Chungui Tian, Xiaomeng Zhang, Lei Wang, Honggang Fu
An in situ catalytic etching strategy is developed to fabricate holey reduced graphene oxide along with simultaneous coupling with a small-sized Mo2 N-Mo2 C heterojunction (Mo2 N-Mo2 C/HGr). The method includes the first immobilization of H3 PMo12 O40 (PMo12 ) clusters on graphite oxide (GO), followed by calcination in air and NH3 to form Mo2 N-Mo2 C/HGr. PMo12 not only acts as the Mo heterojunction source, but also provides the Mo species that can in situ catalyze the decomposition of adjacent reduced GO to form HGr, while the released gas (CO) and introduced NH3 simultaneously react with the Mo species to form an Mo2 N-Mo2 C heterojunction on HGr...
January 2018: Advanced Materials
https://www.readbyqxmd.com/read/28975163/interaction-between-a-water-drop-and-holey-graphene-retarded-imbibition-and-generation-of-novel-water-graphene-wetting-states
#16
Yanbin Wang, Shayandev Sinha, Liangbing Hu, Siddhartha Das
Transport of water through a holey or nanoporous graphene structure in presence of an external force (e.g., a pressure gradient) has paved the way for a myriad of applications ranging from water desalination to water-alcohol separation. In this study, on the other hand, we employ molecular dynamics (MD) simulations to probe no-external-force imbibition/permeation of a water nanodrop through a multilayer holey graphene structure. We carry out MD simulations in a two-dimensional set up; consequently, the holes in the graphene sheets appear as lateral separations between finite-length graphene layers, while the inter-layer distances appear as vertical separations...
October 18, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28901733/preparation-of-graphene-sheets-by-electrochemical-exfoliation-of-graphite-in-confined-space-and-their-application-in-transparent-conductive-films
#17
Hui Wang, Can Wei, Kaiyi Zhu, Yu Zhang, Chunhong Gong, Jianhui Guo, Jiwei Zhang, Laigui Yu, Jingwei Zhang
A novel electrochemical exfoliation mode was established to prepare graphene sheets efficiently with potential applications in transparent conductive films. The graphite electrode was coated with paraffin to keep the electrochemical exfoliation in confined space in the presence of concentrated sodium hydroxide as the electrolyte, yielding ∼100% low-defect (the D band to G band intensity ratio, ID /IG = 0.26) graphene sheets. Furthermore, ozone was first detected with ozone test strips, and the effect of ozone on the exfoliation of graphite foil and the microstructure of the as-prepared graphene sheets was investigated...
October 4, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28848976/coherent-and-incoherent-phonon-transport-in-a-graphene-and-nitrogenated-holey-graphene-superlattice
#18
Xinyu Wang, Man Wang, Yang Hong, Zongrong Wang, Jingchao Zhang
The transition between coherent and incoherent phonon transport in a graphene (GRA) and nitrogenated holey graphene (C2 N) superlattice is investigated by non-equilibrium molecular dynamics (NEMD) simulation. We find that the thermal conductivity of the GRA-C2 N superlattice is much lower than those of graphene and C2 N, and exhibits a positive correlation with the system length. Owing to three mechanisms, i.e., phonon wave interference, phonon confinement and phonon interface scattering, the calculated thermal conductivity shows a decreasing trend at small period length scales and gradually increases at large period length scales...
September 13, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28665014/ferromagnetism-and-half-metallicity-in-atomically-thin-holey-nitrogenated-graphene-based-systems
#19
Indrani Choudhuri, Biswarup Pathak
Metal-free half-metallicity has been the subject of immense research focus in the field of spintronic devices. By using density functional theoretical (DFT) calculations, atomically thin holey nitrogenated graphene (C2 N) based systems are studied for possible spintronic applications. Ferromagnetism is observed in all the C-doped holey nitrogenated graphene. Interestingly, the holey nitrogenated graphene (C2 N) based system shows strong half-metallicity with a Curie temperature of approximately 297 K when a particular C-doping concentration is reached...
September 6, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/28605894/high-density-of-free-standing-holey-graphene-ppy-films-for-superior-volumetric-capacitance-of-supercapacitors
#20
Zhimin Fan, Jianpeng Zhu, Xinghui Sun, Zhongjun Cheng, Yuyan Liu, Youshan Wang
The volumetric performance is a vitally important metric for portable electronic and wearable devices with limited space. However, it is contradictory for the most supercapacitors in the connection between the volumetric and gravimetric capacitances. Herein, we report a simple strategy to prepare a free-standing and binder-free holey graphene/PPy film that possesses a dense microstructure but still high gravimetric capacitances. The holey graphene/PPy film own high-efficiency ion transport channels and big ion-accessible surface area to achieve high-powered supercapacitor electrodes, which have a superior volumetric capacitance (416 F cm-3 ) and high gravimetric capacitance (438 F g-1 ) at 1...
July 5, 2017: ACS Applied Materials & Interfaces
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