Ultrahigh thermopower waves in carbon nanotube‐antimony telluride composites enabled by thermal decomposition of formaldehyde. (10th March 2022) - Seo, Byungseok
Summary: Scattered energy sources are essential to advance sustainable systems with the development of small‐sized devices. Thermopower waves (TWs), which use self‐propagating combustion along micro‐nanostructured composites, can directly convert thermochemical to electrical energy, thereby resolving the configuration limits in small dimensions. However, poor sustainability and energy density, induced by short duration of the combustion should be addressed, although TWs exhibit high‐power densities. Herein, we report the use of formaldehyde (FA)‐activated multi‐walled carbon nanotube (MWCNT) and Sb2 Te3 composites to achieve ultrahigh TWs enabled by the remarkable enhancement of the sustained time and the chemical energy conversion. The FA supports sustained and amplified TWs through its chemical reaction pathways, while the MWCNTs and Sb2 Te3 serves as thermal conduits and thermoelectric materials to generate TWs. The weight ratio of MWCNT and Sb2 Te3 was optimized to produce a high‐power density (~1.1 mW/cm 2 ), and the optimal amount of FA to the tuned MWCNT:Sb2 Te3 ratio resulted in a significantly sustained time (~68.55 seconds, 2698% enhancement compared to without FA). The pre‐decomposed carbon oxides and carbonate from the FA chemical reaction considerably delay self‐propagating reaction and promoted the evaporation of the Te species in Sb2 Te3 and its oxidation to Sb2 O3 and Sb2 O5, which could produce additional energy generation (~0.29 mJ/cm 2 ). A theoretical analysis elucidated the individual contributions of the Seebeck and chemical energy, and rational strategies to enhance the TWs. This work can pave the way for the development of advanced TW devices that satisfy the demands for both high energy density as well as long‐term power generation. Abstract : Formaldehyde‐activated carbon nanotube and Sb2 Te3 composites enable ultralong and ultrahigh thermopower waves. Pre‐decomposed retardants of carbon oxides and carbonate from formaldehyde support sustained time, while the optimal ratio of carbon nanotubes‐Sb2 Te3, and the evaporation of Te species in Sb2 Te3 and its oxidation to Sb2 O3 ‐Sb2 O5 lead to high power and energy density compared with conventional thermopower waves.