Researchers at MIT have discovered a new fuel that can store solar energy as heat. While they are yet to develop an efficient process to convert the heat to electricity, the scientists predict that these solar-fueled nanotubes could outdo lithium batteries in energy production.
When a photoactive molecule absorbs sunlight, it undergoes a conformational change, moving from the ground energy state into a higher energy state. The higher energy state is metastable (stable for the moment, but highly susceptible to energy loss), so a triggerâ€”voltage, heat, light, etc.â€”will cause the molecule to fall back to the ground state. The energy difference between the higher energy state and the ground state (termed Î”H) is then discharged. A useful photoactive molecule will be able to go through numerous cycles of charging and discharging.
Kolpak and Grossman managed to find the right balance between Î”H and activation energy when they examined computational models of azobenzene (azo) bound to carbon nanotubes (CNT) in azo/CNT nanostructures. According to their calculations, placing azobenzene on carbon nanotubes will stabilize both the ground and higher energy states.