Fig. 3: Continuous voltage output and detailed working principle of LEH.
a Schematic illustration of the voltage measurement; one electrode is moving from the wet end to the dry end and back, while the other electrode remains stationary. b Voc change of LEH during measurement, implying a voltage difference could only be generated between the wet and the dry end. c Continuous Voc recording of LEH for 240 h. Insets: Voc change of LEH during the initial moisture absorption process (left), and Voc, temperature, and relative humidity (RH) recording within 145–155 h (right). d The voltage output of energy harvester devices with different substrates (Device number: 10). Both paper and PVA film without the central leaf vein exhibit a voltage reduction after 10 days due to water movement, highlighting the importance of using the leaf as the substrate. e Digital photographs of water movement across the substrates. f Zeta potential (ζ) of CB as a function of iron concentration. g Operando CV measurements of LEH during the moisture absorption process. Scan rate: 0.05 V/s. h Discharge of LEH by capacitors with different capacitances. Electricity harvested by LEH could also be stored inside the capacitors. i Charging LEH through a thermoelectric panel (TE). Energy received by the TE could be maintained inside LEH, implying an application potential of LEH as a low-grade heat harvesting and storage device.
