Overall Objectives of the Project
NGUEC aims to develop experimental protocols for controlled and reproducible functionalization, and characterization of graphene in a nanostructured fashion by using chemisorption (covalent) strategies in combination with physisorption (non-covalent) approaches, relying on the power of electrochemical control.
Noncovalent functionalization of graphene by using physisorption of organic building blocks is an attractive route as it offers the possibility of attaching functional groups without disturbing the unique electronic structure of graphene. Whereas, functionalization of graphene by chemisorption locally leads to changes in the hybridization of the C-atoms, thereby changing its chemistry and electronic properties.
Importance of society
Graphene, a material consisting of a single atom thick sheet of sp2-hybridized carbon, has recently attracted tremendous interest in both fundamental studies and potential applications due to its unique electronic, optical, mechanical and thermal properties. Despite these exceptional qualities however, some inherent characteristics of graphene itself preclude its widespread usage in technological applications. A prerequisite for the use of graphene in several low- as well as high-end applications, is its controlled and reproducible functionalization in a nanostructured fashion, towards doping and band gap opening, a challenge that has not been addressed in a satisfactory way yet. The present, relatively incoherent experimental protocols suffer from following important shortcomings.
- Firstly, graphene functionalization occurs randomly in solution based methods and there is scarcity of methods that can exert precise control over how and where the reactions/interactions occur.
- Secondly, from a fundamental perspective, a molecular level understanding of the functionalization process is still lacking which precludes systematic strategies for manipulation of graphene.
- In addition, the potential of electrochemistry based functionalization protocols and electrochemistry based characterisation approaches in imaging and analysis of graphene is hardly explored.
Therefore, the fundamental understanding at the molecular level attained from this project is a firm basis for manipulating the properties of graphene in a controlled manner leaned on the power of electrochemistry. More importantly, the experimental findings open new avenues to investigate supramolecular self-assembly of doping molecules in nanoconfined spaces under electrochemical control towards bottom-up creation of nanoconfined doped 2D materials for nanoscale electronics applications.
Conclusions of the Action
The main goal of the project is to control molecular patterns on graphitic surfaces using an electrochemical approach. The project has been executed according the work packages and the following conclusions were made:
- The self-assembly of dibenzyl viologen (DBV) on graphitic surfaces was in-situ characterized by electrochemical scanning tunneling microscopy (EC-STM). A combination of Kelvin probe force microscopy (KPFM) and Raman spectroscopy and microscopy results elucidates that the reduced DBV0 adlayer leads to n-doping of graphene. The collective experimental information obtained on the interfacial structure of DBV and the influence of its adsorption phases on the electronic properties of graphene are valuable for engineering DBV/graphene interface based electronic device applications.
- DBV enables to adsorb within “nanocorrals” created by both top-down and bottom-up approaches. The level of control over the size and shape of nanocorrals will allow investigating nucleation and monolayer growth processes in nanoconfined spaces under electrochemical control. In-situ visualization of the self-assembled layer of DBV on graphitic surfaces reveals the possibility to create such nano p-n junctions based on a combination of physi- and chemi-sorption strategies.
