Photothermal conversion materials have attracted wide attention due to their efficient utilization of light energy. In this study, a (GO)/Bi2S3-PVDF/TPU composite nanofiber membrane was systematically developed, comprising GO/Bi2S3nanoparticles (NPs) as a photothermal conversion component and PVDF/TPU composite nanofibers as the substrate. The GO/Bi2S3NPs were synthesized in a one-step way and the PVDF/TPU nanofibers were obtained from a uniformly mixed co-solution by electrospinning. GO nanoparticles with excellent solar harvesting endow the GO/Bi2S3-PVDF/TPU membrane with favorable photothermal conversion. In addition, the introduction of Bi2S3NPs further enhances the broadband absorption and photothermal conversion properties of the GO/Bi2S3-PVDF/TPU composite membrane due to its perfect broadband absorption performance and coordination with GO. Finally, the results show that the GO/Bi2S3-PVDF/TPU composite membrane has the highest light absorption rate (about 95%) in the wavelength range of 400–2500 nm. In the 300 s irradiation process, the temperature changes in the GO/Bi2S3-PVDF/TPU composite membrane were the most significant and rapid, and the equilibrium temperature of the same irradiation time was 81 °C. Due to the presence of TPU, the mechanical strength of the composite film was enhanced, which is beneficial for its operational performance. Besides this, the morphology, composition, and thermal property of the membranes were evaluated by corresponding test methods.Keywords:graphene oxide/bismuth sulfide;solar distillation;nanofiber membrane;photothermal conversion
A flexible temperature and humidity sensor has been developed based on a composite of polyvinylidene fluoride (PVDF) and thermoplastic polyurethane (TPU). The sensor performance was optimized by introducing graphene quantum dots (NGQDs) and ionic liquids (TFSI) into the polymer composite. This type of humidity sensors has high sensitivity, fast response, and excellent stability, making it suitable for use in wearable health monitoring. The addition of TPU into PVDF facilitates the formation of a porous structure which has both a large specific surface area and high hydrophilicity. After optimizing the PVDF/TPU mass ratio to 5:3, such a humidity sensor displays 1.46 times higher sensitivity than that of pure PVDF film, with a linear response range of 10–90% relative humidity. The response time and recovery time are 7.67 s and 6.37 s, respectively. Owing to the improved hydrophobicity, the sensors also exhibit a good stability in a high humidity environment for > 10 days without significant degradation. Moreover, such a composite also has the capability to distinguish normal breathing from rapid breathing, demonstrating its potential in wearable health monitoring.
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