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Holey graphene

Suping Li, Ying Huang, Ding Ling, Na Zhang, Meng Zong, Xiulan Qin, Panbo Liu
In this study, an Fe-Co alloy is coated with carbon and decorated on a holey reduced graphene oxide nanosheet (FeCo@C/HRGO) composite. The structure is synthesized using liquid-phase reduction and hydrothermal processes followed by high-temperature calcination. The FeCo@C/HRGO composite is identified and characterized using XRD, XPS, Raman spectroscopy, TEM, and SEM. This novel composite exhibits excellent electromagnetic-wave absorption properties. The maximum reflection loss for FeCo@C/HRGO reaches -76.6 dB at 16...
February 10, 2019: Journal of Colloid and Interface Science
Dandan Li, Xiangang Hu, Suyan Zhang
The extensive use of graphene-family nanomaterials (GFNs) in biomedicine and other fields has intentionally or unintentionally resulted in their introduction into the blood circulation system, but the effects of the biotransformation of GFNs in blood plasma on their biocompatibility, organ targeting, drug delivery and antitumor ability remain unclear. The present work discovered that GFN sheets were degraded in human blood plasma to holey sheets and aromatic hydrocarbons. The carbon atoms connected with oxygen-containing groups in the planes of GFNs were the initial attack sites for active substances (e...
February 21, 2019: Biomaterials
Donghai Wu, Baocheng Yang, Eli Ruckenstein, Houyang Chen
Electron transfer plays a crucial role in energy storage materials such as metal-ion batteries (MIBs). Numerous approaches are developed to facilitate the electron transfer for MIBs, and most of them are extended the special surface areas, which promote the contact between metal ions and the electrodes. Herein, we report the formation of intramolecular channels for electron transfer to open/close intermolecular channels in sodium-ion batteries (SIBs) through functionalization, modulating the cell performance of two-dimensional (2D) nitrogenated holey graphene C2N anodes...
January 29, 2019: Journal of Physical Chemistry Letters
Aihua Jing, Gaofeng Liang, Yixin Yuan, Wenpo Feng
The quantification of ascorbic acid (AA), dopamine (DA), and uric acid (UA) has been an important area of research, as these molecules' determination directly corresponds to the diagnosis and control of diseases of nerve and brain physiology. In our research, graphene oxide (GO) with nano pores deposited with gold nanoparticles were self-assembled to form three-dimensional (3D) Au/holey-graphene oxide (Au/HGO) composite structures. The as-prepared 3DAu/HGO composite structures were characterized for their structures by X-ray diffraction, Raman spectrum, scanning electron microscopy, and transmission electron microscopy coupled with cyclic voltammograms...
January 24, 2019: Micromachines
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
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
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)
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
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
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
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
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
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
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
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
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
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
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
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
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
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