Bamboo-based hydrovoltaic electricity generation via evaporation potentials

Evaporation potential, generated by the evaporation of water, can be harnessed for energy generation. In bamboo, vascular bundles provide clear pathways for rapid moisture transportation. Meanwhile, the abundance of hydroxyl and carboxyl groups on the wall of vessels and sieve tube enable cation-selective conduction during this process, thereby establishing a potential difference. Leveraging this mechanism, a bamboo-based hydrovoltaic generator (BHG) was designed and fabricated. The stem of moso bamboo was selected as the medium for evaporation, and a copper grid with carbon paste as the electrodes. In deionized (DI) water, the BHG provided a stable open-circuit voltage ( V OC ) of 86 mV, a short circuit current density ( J SC ) of 1.438 μA∙cm −2, and a maximum areal power ( P MA ) of 0.083 μW∙cm −2 . The performance of BHGs was significantly improved in salt solutions. With 3.5 wt% potassium chloride (KCl) solution, a single BHG yielded a stable V OC of 381 mV, J SC of 1.85 μA∙cm −2 , and P MA of 12.66 μW∙cm −2 . Furthermore, the output power could be enhanced by connecting multiple BHGs in series. A series connection of five BHGs provided a stable open circuit voltage between 1.6 and 1.7 V, which was sufficient to power a red light-emitting diode (LED) for over 24 h. • A bamboo-based hydrovoltaic generator (BHG) was developed. • A BHG yields 381 mV VOC, 1.85 μA·cm² JSC and 12.66 μW·cm² PMA in 3.5 wt% KCl. • BHGs in series delivered 1.6–1.7 V voltage and powered a red LED for 24 h.