Laser-induced 3D wood-based skeleton covered with nanostructures for excellent photothermal conversion and electric conductivity

Nanosecond (ns) and femtosecond (fs) lasers have been widely used to induce various micro/nanostructures on the surfaces of different materials to construct functional micro/nanodevices. Compared with metals and semiconductors, wood is a low-cost, eco-friendly material and can be used to fabricate efficient thermal conversion devices using laser processing. In this paper, the carbonized wood (CW) was induced on the surface of wood by ns laser in one step, resulting in high absorbance of 92.5% at the wavelength of 200 to 2000 nm. The scanning electron microscope (SEM) images showed that CW has three-dimensional (3D) skeleton structures. After fs laser reprocessing, nanostripes and nanoparticles were induced on the surface of 3D skeleton structures, forming CW covered with nanostructured (NCW). The temperature of CW increased from 30.9 degrees C to 70.6 degrees C within 30 min under the light irradiation of 1 sun. In contrast, the absorbance of NCW further increased to 95.5%, and the temperature rise rate was increased by 2-3 times. In addition, the non-conductive wood becomes a conductor after laser treatment, and the resistance values of CW and NCW are 160 - 261 & omega;. It was found that CW and NCW have D and G bands in Raman spectra, and the energy dispersive spectra (EDS) analysis shows that the nanostripes and nanoparticles on NCW surface are mainly composed of carbon (C) element. The photothermal conversion property of CW with 3D skeleton structures is further enhanced due to the nanostructures induced by fs laser. CW and NCW have wide applications in solar evaporation, sensor manufacturing, photoelectric devices and so on.