In-Situ Spray Synthesis of Sub-Stoichiometric Titanium Dioxide for Spray-Formed Thermoelectric Generators

The global quest for clean energy production and concurrently reduced greenhouse gas emissions is an ongoing topic, particularly motivated by the rapid acceleration of climate change and global warming. To that end, there has been tremendous emphasis on studying and enabling renewable sources (i.e., wind, solar, etc.) as primary power generation sources. However, given the technological delays in these renewable sources, alternative ‘cleaner’ energy production technologies must be considered.

A large portion of underutilized energy falls under the form of wasted heat. For instance, the exhaust gases in combustion processes (automotive, turbine, etc.). Reclaiming waste heat in the form of usable energy is a topic of constant interest in the materials and engineering communities. However, much research in this field of thermoelectric power generators (TEGs) stems from analysis of sintered bulk materials. In this presentation, the opportunity to use thermal spray manufacturing to form thermoelectric devices is proposed. Here, plasma spray processing by standard DC and cascaded arc processes is used to deposit titanium dioxide (TiO₂). The effect of hydrogen content and particle residence time on the in-flight stoichiometric decomposition of the material was studied, and its relationship to the thermoelectric properties of the material will be shown.