We present an overview of the main techniques for production and processing of graphene and related materials (GRMs), as well as the key characterization procedures. We adopt a ‘hands-on’ approach, providing practical details and procedures as derived from literature as well as from the authors’ experience, in order to enable the reader to reproduce the results. Section is devoted to ‘bottom up’ approaches, whereby individual constituents are pieced together into more complex structures. We consider graphene nanoribbons (GNRs) produced either by solution processing or by on-surface synthesis in ultra high vacuum (UHV), as well carbon nanomembranes (CNM). Production of a variety of GNRs with tailored band gaps and edge shapes is now possible. CNMs can be tuned in terms of porosity, crystallinity and electronic behaviour. Section covers ‘top down’ techniques. These rely on breaking down of a layered precursor, in the graphene case usually natural crystals like graphite or artificially synthesized materials, such as highly oriented pyrolythic graphite, monolayers or few layers (FL) flakes. The main focus of this section is on various exfoliation techniques in a liquid media, either intercalation or liquid phase exfoliation (LPE). The choice of precursor, exfoliation method, medium as well as the control of parameters such as time or temperature are crucial. A definite choice of parameters and conditions yields a particular material with specific properties that makes it more suitable for a targeted application. We cover protocols for the graphitic precursors to graphene oxide (GO). This is an important material for a range of applications in biomedicine, energy storage, nanocomposites, etc. Hummers’ and modified Hummers’ methods are used to make GO that subsequently can be reduced to obtain reduced graphene oxide (RGO) with a variety of strategies. GO flakes are also employed to prepare three-dimensional (3d) low density structures, such as sponges, foams, hydro- or aerogels. The assembly of flakes into 3d structures can provide improved mechanical properties. Aerogels with a highly open structure, with interconnected hierarchical pores, can enhance the accessibility to the whole surface area, as relevant for a number of applications, such as energy storage. The main recipes to yield graphite intercalation compounds (GICs) are also discussed. GICs are suitable precursors for covalent functionalization of graphene, but can also be used for the synthesis of uncharged graphene in solution. Degradation of the molecules intercalated in GICs can be triggered by high temperature treatment or microwave irradiation, creating a gas pressure surge in graphite and exfoliation. Electrochemical exfoliation by applying a voltage in an electrolyte to a graphite electrode can be tuned by varying precursors, electrolytes and potential. Graphite electrodes can be either negatively or positively intercalated to obtain GICs that are subsequently exfoliated. We also discuss the materials that can be amenable to exfoliation, by ...
Copolymerization of epoxides and CO(2) with heterogeneous zinc dicarboxylates is prominent since the early days of this area of chemistry. However, in over 30 years of research, the efficiency of this catalyst system could not be improved significantly. Furthermore, a huge activity difference between zinc glutarate and its lower homologue zinc succinate exists, which could not be explained so far. A detailed investigation of the underlying copolymerization mechanisms on heterogeneous catalysts is therefore necessary. Such investigations are so far lacking, which renders logical improvements of the catalysts difficult. We therefore decided to conduct a detailed investigation on the different zinc-dicarboxylic catalysts, their copolymerization efficiency, solid state structure and supplemented the results with theoretical calculations. The results imply that the widely discussed bimetallic mechanism (for homogeneous catalysts) is in place for heterogeneous zinc dicarboxylates as well. Theoretical calculations conducted to identify an "ideal" Zn-Zn distance suggest an optimal separation of Zn atoms in the range of 4.3-5.0 Å. The combined copolymerization experiments and calculated models give a consistent explanation for the difference in activity of the different zinc-dicarboxylate catalysts and give a hint why the activity of the heterogeneous zinc-dicarboxylate system is limited.
Growth of interest to a field of materials chemistry such as the metal‐organic frameworks (MOFs) demands the comprehensible surveying of new results, and the reviews systematizing and highlighting one or another trend in the MOF research appear periodically. Structural peculiarities of coordination polymers constructed by zinc paddle‐wheel clusters and the investigation of their microporosity are reviewed in detail to emphasize those features of the materials, which are interesting both for the pure and applied chemists.
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