Wood-based material can generate electricity after sunset

Wood-based material generates electricity after sunset

Researchers have created an unusual wood-based material that absorbs sunlight, stores energy as heat and can keep generating electricity after dark. The work demonstrates that ordinary wood can be transformed into a compact, environmentally friendly platform for solar-thermal energy.

Balsa wood structure and light absorption

The scientists chose balsa wood as the base material, as it is lightweight and has a natural network of microchannels. They first removed lignin from the wood to make it more porous. The channel walls were then coated with ultrathin layers of black phosphorene, which efficiently absorbs light across a broad spectrum. To prevent this sensitive material from degrading in air, it was enclosed in a protective coating made from tannic acid and iron ions.

Heat storage for solar-thermal electricity generation

Next, silver nanoparticles were incorporated into the structure to improve light absorption, and the surface was made highly water-repellent. The channels were subsequently filled with stearic acid, a phase-change material that melts when heated and retains heat, before releasing it again as it cools. The resulting heat-storage material is stable and maintains its properties through repeated heating and cooling cycles.

According to the researchers, the system converts up to 91.27% of solar energy into useful heat, stores around 175 kJ/kg and can produce up to 0.65 V when connected to a thermoelectric generator. No noticeable reduction in efficiency was recorded after 100 heating and cooling cycles.

The scientists say this wood-based platform combines several valuable characteristics: fire resistance, moisture resistance, antibacterial protection and resistance to contamination, making it promising for outdoor use. In future, similar materials could be used not only in solar energy systems, but also in electronics, construction materials and autonomous energy systems.