- Engineered wood stores solar heat and releases it to generate electricity.
- Nanoscale Modifications Turn Raft into a Heat-Powered Energy Material
- Phosphorene coating allows for broad-spectrum sunlight absorption and efficient heat conversion
Ordinary balsa wood can now absorb sunlight, store heat and generate electricity even in the dark after a team of Chinese scientists redesigned its cellular architecture.
A team from Kunming University of Science and Technology and Guangdong University of Technology says the internal structure of the wood was transformed to a nanoscale to achieve this result.
They chose balsa not for its strength but for its natural alignment of microchannels, which guide heat and hold other materials in place.
Article continues below.
How the wood-based system really works
The scientists first removed lignin, the component that gives wood its color and rigidity, increasing the material’s porosity to above 93%.
They then covered the walls of the channel with ultrathin sheets of black phosphorene, a material that absorbs sunlight across ultraviolet, visible and infrared wavelengths and converts it directly into heat.
Each phosphorene nanosheet received a protective layer made of tannic acid and iron ions, creating a molecular shield that prevents oxidation.
Even after 150 days of sun exposure, the coated material remained stable.
Silver nanoparticles were added to enhance light absorption through plasmonic effects, while long hydrocarbon chains were grafted onto the surface to make it water-repellent.
The finished structure had a contact angle of 153 degrees, meaning water simply runs off.
The channels were filled with stearic acid, a bio-based phase change material that stores heat when it melts and releases it upon solidifying.
The material stored approximately 175 kJ of heat per kilogram and converted 91.27% of incoming sunlight into usable heat.
It conducted heat approximately 3.9 times more efficiently along the grain of the wood. When combined with a thermoelectric generator, it produces up to 0.65 V under standard sunlight.
When sunlight hits the material, it melts the stearic acid and the heat is gradually released at dusk to maintain a temperature difference throughout the generator.
This allows the system to continue producing electricity even after the light source runs out.
After 100 heating and cooling cycles, the material’s performance barely changed. It also resisted burning by self-extinguishing within two minutes.
Scientists point out that its design is flame retardant, superhydrophobic and antimicrobial, which prevents dust and microbes from degrading outdoor performance.
Similar designs could help manage heat in electronics, improve energy efficiency in building materials, or support small off-grid power systems.
The research is published in Advanced Energy Materials, but the gap between a laboratory-tested prototype and a commercially viable product remains substantial.
The team avoided high-temperature carbonization to preserve the wood’s chemical characteristics, which shows promise for scalability.
However, producing this material at scale while maintaining its complex layered structure will not be easy.
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