Textile-Based Asymmetric Hierarchical Systems for Constant Hydrovoltaic Electricity Generation

Converting natural resources into electricity is an essential part of the transition to sustainable energy generation. Evaporation-driven moist-electric generators (EMEGs) are an emergent technology and show great potential for harvesting clean energy. In this paper, we report a flexible textile EMEG based on the decoration of an asymmetric micro-nano hierarchical capillary system on the cotton fabric. When water droplets encounter this textile EMEG, the water flows spontaneously under capillary action without requiring an external power supply, resulting in a constant generation of voltages up to 0.65 V and currents up to 8 μA on a small piece of sample with size of 2 cm × 5.5 cm × 0.2 mm (0.16 mL of water can induce a constant electric output for more than 3600 s). More importantly, even when fully wetted or totally immersed in water, the EMEG can maintain its electrical output owing to its inherent electrochemical asymmetry. Furthermore, the output can be enhanced by integrating multiple units, generating sufficient power to drive LED devices, while the energy can also be stored in supercapacitors. This study is of high value for designing of versatile electric generator to harvest clean energy constantly.