Scalable and Environmentally Friendly MXene-Tetrahedrites for Next-Generation Flexible Thermoelectrics

Traditional thermoelectric generators (TEGs) for harvesting low waste heat energy in room-temperature environments face scalability challenges due to high-temperature, long-duration curing processes and the use of rare-earth and toxic chalcogenides like Bismuth Telluride. Additive manufacturing has been investigated as a more time-, energy- and cost-efficient method that offers greater flexibility than traditional manufacturing techniques. Additionally, tetrahedrites are promising thermoelectric materials (TE) in high-temperature applications because they are non-toxic and earth-abundant. Herein, this work demonstrates the fabrication of scalable and sustainable Cu₁₂Sb₄S₁₃ (CAS) based composite films and flexible TEG devices (f-TEGs) with 2D MXene nanosheets using a low-thermal budget additive manufacturing approach for room temperature applications. 2D MXene nanosheets introduced energy-barrier scattering and nanoscale features to effectively increase the room-temperature ZT to 0.22, 10% higher than bulk CAS, by decoupling electrical conductivity, Seebeck coefficient, and thermal conductivity. CAS and 2D MXenes were found to be environmentally safe through a bacterial viability study. The process is used to create a 5-leg f-TEG device producing a power of 5.3 µW at a temperature difference of 25 K, this work demonstrates that combining scalable and sustainable materials and methods is an effective strategy for high-performance room-temperature f-TEGs. Furthermore, a study evaluated the effects of Chitosan-CAS and Chitosan-CAS-MXene inks on the gram-negative bacterium Shewanella Oneidensis MR-1, demonstrating that both CAS and MXene inks are environmentally safe.