Here, we couple exothermic chemical reaction with a nanotube or a nanowire having high thermal conductivity. Exothermic nature of the fuel coupled with high thermal conductivity gives rise to a self-propagating reaction wave along the length of the nanotube. We have studied such waves using cyclotrimethylene trinitramine as a fuel on multiwalled carbon nanotubes conduit. The reaction waves propagate at extremely high velocities of the order of about 2 ms-1. The waves also give rise to an electrical output across the ends of the nanotube. Electrical pulses of specific power as high as 7 kW kg-1were experimentally observed. This phenomenon of a self-propagating reaction wave leading to an electrical pulse generation was identified as thermopower waves. Studies show that the specific power scales inversely with the system size. This kind of energy source could have many potential applications because of its long shelf life and rapid energy discharge.
Current work on thermopower waves covers a wide horizon of possible improvements and applications. We are working on developing a ‘fuel cell’ working on the concept of thermopower waves. It offers advantage of being able to use liquid fuels and provide ease of device reusability. Studies to increase the device efficiency and understand the physics of this phenomenon of improved electrical output because of the reaction wave are underway. The final objective would be to make a ‘battery’ that can be used as a power source for various micro and nano scale operations.
Choi, W. et al. Chemically driven carbon-nanotube-guided thermopower waves. Nat Mater 9, 423-429, (2010).