Superelastic wood-based nanogenerators magnifying the piezoelectric effect for sustainable energy conversion

In the quest for sustainable energy materials, wood is discovered to be a potential piezoelectric material. However, the rigidity, poor stability, and low piezoelectric properties of wood impede its development. Here, we obtained a superelastic roasted wood nanogenerator (RW-NG) by unraveling ray tissues through a sustainable roasting strategy. The increased compressibility of roasted wood intensifies the deformation of cellulose microfibrils, significantly enhancing the piezoelectric effect in wood. Roasted wood (15 × 15 × 15 mm³, longitudinal × radial × tangential) can generate a voltage and current outputs of 1.4 V and 14.5 nA, respectively, which are more than 70 times that of natural wood. The wood sample can recover 90% of its shape after 5000 compressions at 65% strain, exhibiting excellent elasticity and stability. Importantly, roasted wood does not add any toxic substances and can be safely applied on the human skin as a self-powered sensor for detecting body movements. Moreover, it can also be assembled into self-powered wooden floors for energy harvesting. These indicate that roasted wood has great potential for sustainable sensing and energy conversion.