Evaporating potential in a conical PTFE membrane with asymmetric electrodes†

Power generation from natural evaporation receives great attention as water evaporation is a ubiquitous process. However, the energy devices may not have the normal geometry that results in different flow and energy conversion behaviors. Here, a conical polytetrafluoroethylene (PTFE) hydrovoltaic generator with asymmetric electrodes is proposed to study the effect of membrane structure and electrode matching on power generation. An asymmetric membrane structure optimizes the capillary flow that generates a more effective velocity in the top areas of the generator, which induces a higher voltage sign. Meanwhile, the directed asymmetric electrodes synergize interfacial and streaming potentials. As a result, the forward conical structure with C–Cu electrodes obtains the optimal energy conversion performance. Subjecting such a device to environmental conditions, it can induce a ∼0.4 V open circuit voltage and remain stable for around 20 hours without noticeable fluctuations. The facile structure and electrode matching optimizes the power generation, providing valuable insights into sustainable energy harvesting.