Graphene, a two-dimensional, all-carbon material, has been referred to as the plastic of the XXI century. It has very high thermal and electrical conductivity, large surface per unit weight, and exceptional mechanical resistance despite its extreme thinness. These properties – mainly related to the combination of its honeycomb structure and the electronic structure of carbon – immediately suggest application in the fields of high-tech (e.g. flexible electronic devices), clean energy (e.g. hydrogen technology), environment (e.g. water and hair purification), and medicine (e.g. nano-prosthetics).
However, bare graphene is not always optimal for applications. It is a metal with high carrier mobility, but needs electronic doping to have sufficient carriers density or manipulation to transform into a semiconductor. As it is light and with a large surface to mass ratio, graphene has great potential for gas storage and catalysis. However, it has low chemical and physical reactivity. As a consequence, for most applications, graphene needs some sort of manipulation, which must be conducted at the nano-scale level to optimally exploit graphene properties. Manipulation implies the disruption of its perfect symmetry through controlled creation of different defects. One can then say that the next challenge in the graphene era is its nano-scale controlled morphing.
Because most morphing actions consist of local structural or chemical transformations (e.g. substitutional doping, defect or added atoms), control of morphing can be translated into control of local reactivity. The main aim of GRAFLEX was to achieve this task by controlling graphene local curvature. This idea stems from the following observations: (i) graphene is extremely flexible as a consequence of its symmetry and 2D nature; (ii) there are indications that reactivity depends directly on local curvature: as graphene is deformed, its electronic structure is locally disturbed and becomes more prone to interactions with other substances; and (iii) graphene curvature is sensitive to external electrostatic fields a phenomenon related to flexo-electricity. The overall objectives of GRAFLEX were therefore quantifying the dependence of reactivity on the local curvature and studying the possibility of using external electric fields to manipulate curvature and reactivity.
The project GRAFLEX was funded by Marie Skłodowska-Curie (CAR) action of EU-Horizon 2020 and hosted at the Istituto Nanoscienze (NANO-Cnr, Pisa). It supported the Georgian researcher Khatuna Kakhiani with a 2-year fellowship (2015-2017) to collaborate with NANO senior scientist Valentina Tozzini. The GRAFLEX project concluded in September 7th, 2017, but it was the beginning of a fruitful collaboration between the two scientists and their respective institutions.
