Harvesting energy from water evaporation: a green power device printed from waste bamboo

Abstract

A water evaporation-driven power generator (WEPG) generates sustainable energy through the interaction between substances and water. However, achieving flexibility, low cost, high efficiency, and recyclability remains a major challenge. Natural biomass materials possess the advantages of being environmentally friendly, structurally adaptable, and cost-controllable. They show great potential for sustainable development in WEPG applications. However, research on natural biomass materials remains limited to their original forms and structures. Herein, a biomass-based carbon micro-material (BC) is prepared from waste residues. Through a three-step collaborative strategy of high-temperature carbonization, acidification treatment, and doping with conductive carbon black, the surface functional groups of BC are modified, resulting in the material (BC-H⁺) with excellent hydrophilicity and a high surface charge density. Furthermore, the BC-H⁺ based flexible WEPG is fabricated using screen printing, enabling high flexibility, miniaturization, and integration. This device can achieve a record-breaking power density of 54 µW cm⁻², outperforming most inorganic and organic evaporation materials. This green, pollution-free, printable WEPG technology provides a new path for the application of flexible electronics.