共查询到20条相似文献,搜索用时 31 毫秒
1.
Christian E. Halbig Roman Lasch Jasmin Krüll Anna S. Pirzer Zhenping Wang Jan N. Kirchhof Kirill I. Bolotin Markus R. Heinrich Siegfried Eigler 《Angewandte Chemie (International ed. in English)》2019,58(11):3599-3603
The development of versatile functionalization concepts for graphene is currently in the focus of research. Upon oxo‐functionalization of graphite, the full surface of graphene becomes accessible for C?C bond formation to introduce out‐of‐plane functionality. Herein, we present the arylation of graphene with arylazocarboxylic tert‐butyl esters, which generates aryl radicals after activation with an acid. Surprisingly, the degree of functionalization is related to the concentration of lattice vacancy defects in the graphene material. Consequently, graphene materials that are free from lattice defects are not reactive. The reaction can be applied to graphene dispersed in solvents and leads to bitopic functionalization as well as monotopic functionalization when the graphene is deposited on surfaces. As the arylazocarboxylic tert‐butyl ester moiety can be attached to various molecules, the presented method paves the way to functional graphene derivatives, with the density of defects determining the degree of functionalization. 相似文献
2.
Fabian Grote Christoph Gruber Dr. Felix Börrnert Prof. Dr. Ute Kaiser Prof. Dr. Siegfried Eigler 《Angewandte Chemie (International ed. in English)》2017,56(31):9222-9225
Graphene production by wet chemistry is an ongoing scientific challenge. Controlled oxidation of graphite introduces oxo functional groups; this material can be processed and converted back to graphene by reductive defunctionalization. Although thermal processing yields conductive carbon, a ruptured and undefined carbon lattice is produced as a consequence of CO2 formation. This thermal process is not understood, but it is believed that graphene is not accessible. Here, we thermally process oxo-functionalized graphene (oxo-G) with a low (4–6 %) and high degree of functionalization (50–60 %) and find on the basis of Raman spectroscopy and transmission electron microscopy performed at atomic resolution (HRTEM) that thermal processing leads predominantly to an intact carbon framework with a density of lattice defects as low as 0.8 %. We attribute this finding to reorganization effects of oxo groups. This finding holds out the prospect of thermal graphene formation from oxo-G derivatives. 相似文献
3.
Highly Intact and Pure Oxo‐Functionalized Graphene: Synthesis and Electron‐Beam‐Induced Reduction 下载免费PDF全文
Dr. Benjamin Butz Christian Dolle Christian E. Halbig Prof. Dr. Erdmann Spiecker Prof. Dr. Siegfried Eigler 《Angewandte Chemie (International ed. in English)》2016,55(51):15771-15774
Controlling the chemistry of graphene is necessary to enable applications in materials and life sciences. Research beyond graphene oxide is targeted to avoid the highly defective character of the carbon framework. Herein, we show how to optimize the synthesis of oxo‐functionalized graphene (oxo‐G) to prepare high‐quality monolayer flakes that even allow for direct transmission electron microscopy investigation at atomic resolution (HRTEM). The role of undesired residuals is addressed and sources are eliminated. HRTEM provides clear evidence for the exceptional integrity of the carbon framework of such oxo‐G sheets. The patchy distribution of oxo‐functionality on the nm‐scale, observed on our highly clean oxo‐G sheets, corroborates theoretical predictions. Moreover, defined electron‐beam irradiation facilitates gentle de‐functionalization of oxo‐G sheets, a new route towards clean graphene, which is a breakthrough for localized graphene chemistry. 相似文献
4.
Single‐Step Functionalization and Exfoliation of Graphene with Polymers under Mild Conditions 下载免费PDF全文
T. Skaltsas Dr. G. Mountrichas S. Zhao Prof. H. Shinohara Dr. N. Tagmatarchis Dr. S. Pispas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(51):18841-18846
The simultaneous polymer functionalization and exfoliation of graphene sheets by using mild bath sonication and heat treatment at low temperature is described. In particular, free‐radical polymerization of three different vinyl monomers takes place in the presence of graphite flakes. The polymerization procedure leads to the exfoliation of graphene sheets and at the same time the growing polymer chains are attached onto the graphene lattice, which gives solubility and stability to the final graphene‐based hybrid material. The polymer‐functionalized graphene sheets possess fewer defects as compared with previously reported polymer‐functionalized graphene. The success of the covalent functionalization and exfoliation of graphene was confirmed by using a variety of complementary spectroscopic, thermal, and microscopy techniques, including Raman, IR and UV/Vis spectroscopy, thermogravimetric analysis, and transmission electron microscopy. 相似文献
5.
Dr. Chun Kiang Chua Prof. Zdeněk Sofer Jan Luxa Prof. Martin Pumera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8090-8095
Nitrogen functionalization of graphene offers new hybrid materials with improved performance for important technological applications. Despite studies highlighting the dependence of the performance of nitrogen‐functionalized graphene on the types of nitrogen functional groups that are present, precise synthetic control over their ratio is challenging. Herein, the synthesis of nitrogen‐functionalized graphene rich in amino groups by a Bucherer‐type reaction under hydrothermal conditions is reported. The efficiency of the synthetic method under two hydrothermal conditions was examined for graphite oxide produced by Hummers and Hofmann oxidation routes. The morphological and structural properties of the amino‐functionalized graphene were fully characterized. The use of a synthetic method with a well‐known mechanism for derivatization of graphene will open new avenues for highly reproducible functionalization of graphene materials. 相似文献
6.
7.
Graphene has recently found applications in a wide range of fields. Density functional calculations show that halide ions can be adsorbed on pristine graphene, but only F? has an appreciable binding energy (?97.0 kJ mol?1). Graphene materials, which are mainly electron donors, can be made strong electron acceptors by edge functionalization with F atoms. The binding strengths of halide ions are greatly enhanced by edge functionalization and show direct proportionality with the degree of functionalization Θ and increased charge transfer. In contrast, the adsorption strengths of metal ions on pristine graphene are clearly superior to those of halide ions but decline substantially with increasing degree of edge functionalization, and for Θ=100 %, the binding energies of ?95.7, ?44.8, and ?25.9 kJ mol?1 that are calculated for Li+, Na+, and K+, respectively, are obviously inferior to that of F? (?186.3 kJ mol?1). Thus, the electronic properties of graphene are fundamentally regulated by edge functionalization, and the preferential adsorption of certain metal ions or anions can be facilely realized by choice of an appropriate degree of functionalization. Adsorbed metal ions and anions behave differently on gradual addition of water molecules, and their binding strengths remain substantial when graphene materials are in the pristine and highly edge functionalized states, respectively. 相似文献
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.