**1. Introduction**

Graphene [1–3] is the thinnest material on Earth and is commonly considered as a single layer of graphite. It has a two‐dimensional conjugated structure, good thermal stability, very high aspect ratio and specific surface area and has, as a consequence, outstanding electronic, thermal and mechanical properties. At low temperatures and high magnetic fields, quantum Hall effect has been observed in graphene layers for both electrons and holes [4, 5]. The in‐plane thermal conductivity of graphene is among the highest recorded for known materials, about 2000–4000 W m−1 K−1 at room temperature [6, 7]. A graphene sheet has theoretical elastic modulus of over 1 TPa and Young modulus of about 1060 MPa [8, 9].

In the light of such properties, impressive research activity is currently carried out for applying graphene in high‐performance materials [10], in fields such as nanoelectronics [3], energy storage and energy conversion [11]. Graphene composites allow contributing the exceptional properties of graphene to the macroscopic scale. In particular, light, flexible, robust and conductive graphene papers find a broad spectrum of applications such as electrochemical energy storage devices [12], catalyst supports and fuel cells [13], sensors and actuators [14], chemical filters and membranes [15] and structural composites [16].

Graphene and derivatives are also finding increasing applications in the field of catalysis [17, 18]. Indeed, carbocatalysis is largely used for promoting synthesis and transformation of organic or inorganic substrates: carbons favour reduction, oxidation and bond‐forming reactions [19].

All the applications mentioned above become successful if graphene or graphitic aggregates made by only few layers of graphene can be used. Large research efforts are thus made in order to prepare graphene and few‐layer graphene [3, 10, 20–23].

Moreover, high interest is on functionalization of graphene layers [24–33]. Graphene oxide is considered a stable carbon framework to be functionalized [24] and, as it will be discussed in the next paragraph, is the product of the first step of the oxidation‐reduction process aimed at preparing graphene starting from graphite. It is thus the subject of much of the research on functionalization [24–26].

In our group, research was performed with the following objectives:


In a nutshell, our main goal was the controlled functionalization of graphene layers.

The present chapter summarizes the results of such a research.
