Fabrication and surface modification of flat lignocellulosic carbon materials

Flat lignocellulosic carbon materials (FLCMs) with a honeycomb structure were successfully fabricated by carbonizing the softwood Picea jezoensis (Ezomatsu, Japanese conifer) and the hardwood Cercidiphyllum japonicum (Katsura). Scanning electron microscopy images of the FLCMs showed distinct differences in the tracheid diameter distributions between the FLCMs made from the softwood and hardwood. Hightemperature heating decreased the electrical resistivity of the FLCMs. Vacuum ultraviolet irradiation in an oxygen atmosphere (VUV/O₃) helped in increasing the surface hydrophilicity and specific surface area of the materials while maintaining their low electrical resistivity. The surface-treated FLCMs were successfully used to fabricate self-supporting electrodes for electric double-layer capacitors (EDLCs).