水蒸发驱动柔性自支撑复合发电碳膜

Evaporation induced electricity generation in freestanding and flexible carbon-based hybrid film

利用自然界中无处不在的蒸发作用,收集利用环境中总量巨大的低品位热能是一种新型可持续能源技术.本文制备了一种可直接通过蒸发驱动流动的方式将环境热能转化为电能的柔性自支撑复合碳膜.该复合碳膜由碳颗粒和玻璃纤维组成,具有类似钢筋混凝土结构,因而有良好的柔性和抗拉伸性能.一片尺寸为1 cm×4.5cm×0.13 mm的复合碳膜最高可获得~1 V的开路电压和~0.86μA的短路电流.通过放大面积,最高可得到单个器件~1 V的开路电压和~28μA的输出电流.复合碳膜的这些性质显示了其作为一种新型的可收集环境能源材料,在绿色可持续能源利用方面的应用前景.

Energy harvesting from ambient environment attracts widespread interest for its great potential in green and sustainable development. Very recently, evaporation, a ubiquitous process existing in nature was demonstrated as a reliable process, which can convert low-grade thermal energy in environment into electricity. Evaporation-driven water flow within a piece of carbon black sheet or printed porous carbon film could generate sustainable direct-current electricity with open-circuit voltage（Voc） up to 1 V, and with lifetime over hundreds of hours. However, both the flame-deposited carbon black sheets and all-printed porous carbon films need to be deposited or printed on rigid substrates（e.g., silica glass and Al2O3 plate） in the previous work, which has deceased the effective evaporation area and occupied excessive space, thus limiting the application of this new energy harvesting strategy as a practical power source. In this work, we present the fabrication of a flexible and freestanding carbon nanoparticles/glass fiber hybrid film（CNGF） for electricity generation via evaporation-driven water flow within it. The CNGF hybrid film has a structure of reinforced concrete, thus exhibits good flexibility and mechanical properties. The carbon film with the size of 1 cm×4.5 cm×0.13 mm and glassfiber/carbon nanoparticle mass ratio of 0.6, has a max tensile stress of 4.9 MPa. The electrical resistance of the carbon film keeps nearly unchanged after 10000 bends at a max bending angle of 90°, indicating its excellent flexibility. Without the limit of rigid substrates, the double-side evaporation enables higher water flow rate through the film. The freestanding carbon film thus has higher electrical power output than the carbon films reported before. A device with the size of 1 cm×4.5 cm×0.13 mm generates an open-circuit voltage of -1 V and current of - 0.86 μA under ambient condition. The hybrid carbon film can also be easily scaled-up. We demonstrated a carbon film with the maximum width of 40 cm, which has an output current of -28 μA. Furthermore, the excellent flexibility allows the film to be rolled up to save space, even with a high power output. To demonstrate the application of carbon film, we successfully degraded methylene blue（MB） by using our device as power source. Given the simple fabrication, robust mechanical property, high electricity output, such a freestanding and flexible carbon-based hybrid film shows great potential in environmental energies harvesting for green and sustainable development.