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Holey graphene

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 1, 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...
July 11, 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
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
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
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
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
Zhong-Jie Jiang, Zhongqing Jiang, Xiaoning Tian, Lijuan Luo, Meilin Liu
Sulfonated holey graphene oxides (SHGOs) have been synthesized by the etching of sulfonated graphene oxides with concentrated HNO3 under the assistance of ultrasonication. These SHGOs could be used as fillers for the sulfonated aromatic poly(ether ether ketone) (SPEEK) membrane. The obtained SHGO-incorporated SPEEK membrane has a uniform and dense structure, exhibiting higher performance as proton exchange membranes (PEMs), for instance, higher proton conductivity, lower activation energy for proton conduction, and comparable methanol permeability, as compared to Nafion 112...
June 14, 2017: ACS Applied Materials & Interfaces
Long Qie, Yi Lin, John W Connell, Jiantie Xu, Liming Dai
Metal-air batteries, especially Li-air batteries, have attracted significant research attention in the past decade. However, the electrochemical reactions between CO2 (0.04 % in ambient air) with Li anode may lead to the irreversible formation of insulating Li2 CO3 , making the battery less rechargeable. To make the Li-CO2 batteries usable under ambient conditions, it is critical to develop highly efficient catalysts for the CO2 reduction and evolution reactions and investigate the electrochemical behavior of Li-CO2 batteries...
May 16, 2017: Angewandte Chemie
Hongtao Sun, Lin Mei, Junfei Liang, Zipeng Zhao, Chain Lee, Huilong Fei, Mengning Ding, Jonathan Lau, Mufan Li, Chen Wang, Xu Xu, Guolin Hao, Benjamin Papandrea, Imran Shakir, Bruce Dunn, Yu Huang, Xiangfeng Duan
Nanostructured materials have shown extraordinary promise for electrochemical energy storage but are usually limited to electrodes with rather low mass loading (~1 milligram per square centimeter) because of the increasing ion diffusion limitations in thicker electrodes. We report the design of a three-dimensional (3D) holey-graphene/niobia (Nb2 O5 ) composite for ultrahigh-rate energy storage at practical levels of mass loading (>10 milligrams per square centimeter). The highly interconnected graphene network in the 3D architecture provides excellent electron transport properties, and its hierarchical porous structure facilitates rapid ion transport...
May 12, 2017: Science
Lele Peng, Pan Xiong, Lu Ma, Yifei Yuan, Yue Zhu, Dahong Chen, Xiangyi Luo, Jun Lu, Khalil Amine, Guihua Yu
Transition metal oxide nanomaterials are promising electrodes for alkali-ion batteries owing to their distinct reaction mechanism, abundant active sites and shortened ion diffusion distance. However, detailed conversion reaction processes in terms of the oxidation state evolution and chemical/mechanical stability of the electrodes are still poorly understood. Herein we explore a general synthetic strategy for versatile synthesis of various holey transition metal oxide nanosheets with adjustable hole sizes that enable greatly enhanced alkali-ion storage properties...
April 26, 2017: Nature Communications
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