• Calorimetry
• Functionalization
• Graphene
• Hydrogen Storage
• Titanium

This thesis reports the research work on the calorimetric detection and analysis of hydrogen adsorption on titanium-decorated graphene. The entire investigation has been realized at the facilities of Laboratorio NEST. The sample preparation has been done in clean and controlled conditions (cleanroom), and the measurements have been performed in an Ultra-High Vacuum environment (UHV chamber of a RHK Technology Scanning Tunneling Microscope).
This study is inserted in a wider research context on hydrogen storage systems.
In fact, because of the variety of environmental problems in burning fossil fuels (coal, oil, and gas) as the massive release of carbon dioxide or the contribution in acid rain and air pollution, the research of new sustainable alternative energies has been very active recently. However, while solar and wind energy production are mature technologies already developed, the problem of energy storage is still unsolved.
In this direction one of the most promising energy carriers is hydrogen, which, once produced, can be stored for a long period. When energy is requested, the same amount of energy that has been provided for its production will be released during its use in fuel cells. Actually, the major drawback in the use of hydrogen as energy carrier is the lack of effocient storage systems.
For that reason, solid-state graphene-based devices are extensively investigated for their application in the hydrogen storage field. In particular, functionalized mono-layer graphene has shown interesting properties such as stable hydrogen storage, fast adsorption and desorption, desorption energies in a range useful for practical application, and in perspective high storage density.
In this thesis work an original thermometric technique to monitor hydrogen storage has been utilized. We focus on the functionalization of mono-layer graphene with titanium, which is a widely investigated system and can be used as a reference material. The first direct detection of the exothermic adsorption of molecular hydrogen on Ti-decorated graphene at room temperature is presented. Then, the calorimetric analysis and the enthalpy release calculation are discussed, and future improvements and applications are presented.