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 ...

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We prepared a series of graphene-like materials by thermal exfoliation/reduction of a graphite oxide (GO) at temperatures between 127ºC and 2400ºC. The extent of the exfoliation and reduction of the GO at different temperatures, as well as the impact on the resultant graphene-like materials (TRGs), were studied through their chemical/structural characterization. The main oxygen loss was observed at 127ºC during the blasting of the GO, which produced its exfoliation into monolayer functionalized TRG with hydroxyl groups and minor amounts of epoxy and carboxyl groups. Above 600ºC, the reduction continued smoothly, with oxygen and hydrogen loss and the conversion of hybridized carbon atoms from sp 3 into sp 2 . 1000ºC appears to be a critical temperature for the efficiency of the reduction process, as the resulting TRG contained less than 2% oxygen and 81.5% sp 2 -carbon atoms. The materials obtained at 2000ºC and 2400ºC were almost oxygen-free and the layers exhibited a dramatic restoration of the pristine graphite structure, as confirmed by the increase in the average size of the sp 2 -domains. The typical * Corresponding author: Fax. + 34 985 29 76 62; E-mail: rosmenen@incar.csic.es (Prof. R. Menéndez) 2 disordered stacking of TRGs increases with temperature, although they can be dispersed yielding monolayers at 127 and 300°C and stacks of up to 4-6 layers above 1000°C, as determined by AFM.

Graphene materials containing different functional groups were prepared from a natural graphite, by means of two different oxidation methods (Hummers and Brodie). It was observed that the differences in the structure of the resultant graphite oxides (GOs) greatly affect the structure of the graphenes resulting from their thermal exfoliation/reduction. Although the oxidation of the graphite was more effective with the modified Hummers method than with Brodie´s method (C/O of 1.8 vs 2.9, as determined by XPS), the former generated a lower residual oxygen content after thermal exfoliation/reduction and a better reconstruction of the 2D graphene structure (with fewer defects). This is explained by the presence of conjugated epoxy and hydroxyl groups in the GO obtained by Brodie´s method, which upon thermal treatment, lead to the incorporation of oxygen into the carbon lattice preventing its complete restoration. Additionally, graphene materials obtained with Brodie´s method exhibit, in general, a smaller sheet size and larger surface area.

The effect of the parent graphite on the structure of graphene oxide (GO) is investigated using high purity graphites with a uniform crystallite size. Our results provide direct evidence of how the size of the graphite crystal affects the oxidation process and the functionality and sheet size of the resulting GO. The important role of the crystal boundaries in the graphite with smaller crystallites is confirmed by the smaller size of the GO sheets obtained and also by the presence of carboxylic groups, located at the edges of the sheets. However, functionalization in the graphite with larger crystals mainly occurs in the vicinity of basal plane defects, as evidenced by the larger number of epoxy groups. Thus, this study leads to a better understanding of the oxidation process of graphite and provides a way to produce GOs suitable for different applications.