Thermoelectric materials have attracted considerable interest in the field of fire warning because of the accuracy and repeatability of their thermoelectric effect. Nevertheless, the incompatibility between high thermoelectric efficiency and flexibility restricts their application in flexible electronic materials. Herein, the dilemma was overcome by constructing a flexible thermoelectric nanocoating with layered heterostructure through the co-assembly of thermoelectric graphene (TEG) nanosheets and carboxymethyl cellulose (CCS). Layered heterostructure not only exhibited exceptional flexibility, but also enabled repeatable sensitive thermosensation of the nanocoating. The nanocoating could accurately monitor the temperature rise stage (50–350 ℃) of a fire, and trigger the fire-warning within 1.5 s when encountering flame. Even it was reburned, the nanocoating still triggered the fire-warning within 2.6 s. Besides, the compact layered structure endowed the nanocoating with efficient flame retardancy. The coated polyester film reached a limiting oxygen index of 33.7 % and self-extinguished in vertical burning test. This flexible thermoelectric nanocoating may pave the way toward high fire safety for flexible electronic materials.
Sijing Liu,Yuewang Yang,He Huang,Jiongzhi Zheng,Gongze Liu,Tsz Ho To,Baoling Huang
Ionic thermoelectrics show great potential in thermal sensing owing to their ultrahigh thermopower, low cost, and ease in production. However, the lack of effective n-type ionic thermoelectric materials seriously hinders their applications. Here, we report giant and bidirectionally tunable thermopowers within an ultrawide range from −15 to +17 mV K −1 in solid ionic liquid–based ionogels. Particularly, a record high negative thermopower of −15 mV K −1 is achieved in the ternary ionogel, rendering it among the best n-type ionic thermoelectric materials under the same condition. A thermopower regulation strategy through ion doping to selectively induce ion aggregates to enhance ion-ion interactions is proposed. These selective ion interactions are found to be decisive in modulating the sign and magnitude of the thermopower in the ionogels. A prototype wearable device integrated with 12 p-n pairs is demonstrated with a total thermopower of 0.358 V K −1 , showing promise for ultrasensitive thermal detection.
Hao Li,Jiawei Wang,Ziwei You,Yuxi Yu,Pai Li,Liwei Xiong,Yunbin He
VO 2 thin films are widely studied materials for uncooled infrared detection because of their high temperature coefficient of resistance. In this research, Nb-doped VO 2 films were synthesized with the expectation that Nb doping would reduce the metal-insulator-transition temperature via electron doping and strain effects caused by the relatively large ionic radius of Nb, thus improving the resistance temperature coefficient of the doped films. The doped films displayed superior thermal sensing abilities compared with pure VO 2 films. As the amount of Nb doping increased, the thermal hysteresis and resistivity of the doped films decreased, while the transition temperature range widened. When the Nb-doping content reached 10%, the temperature coefficient of resistance reached -3.2%/K, while the metal-insulator transition temperature dropped to 52.2 °C. The high performance of the doped films proved that the strategy of Nb doping in VO 2 was promising for thermal-sensing applications.
Han Zhang,Sixv Zhu,Beibei Guo,Dongyun Wan,Hongjie Luo,Yanfeng Gao
This work first reports the controllable preparation of rGO/VO 2 (B) intercalation films via a simple sol-gel method at relative low temperature (420 °C). The excellent conductance and thermal conductivity of rGO could significantly enhance the performance and sensitivity of VO 2 (B) films to be used for uncooled infrared detectors . Aluminum (Al) reduction is introduced to reduce the oxygen-containing functional groups of graphene oxide (GO) and V 2 O 5 of GO/V 2 O 5 intercalation films in a two-zone furnace. According to our results, the reduced-GO (rGO), as a fast channel for electron transport , was inserted into the VO 2 (B) film, and thus the electron transfer between rGO/VO 2 (B) intercalation films occurs much faster than in pure VO 2 (B) films. The film preparation processes were optimized through adjusting the doping concentration of rGO, and rGO/VO 2 (B) intercalation films with applicable temperature coefficient of resistance (TCR) (−2.78%/K) and square-resistance (21.22 kΩ) were achieved. Our work provided a promising and feasible technique to convict the cost and complexity of high vacuum method used to fabricate the VO 2 thermal sensing thin films .
危险品化学品经营许可证（带存储）