Boosting Electrical Conductivity of Sugarcane Cellulose and Lignin Biocarbons through Annealing under Isopropanol Vapor

Annealing of sugarcane bagasse cellulose or lignin biocarbons under isopropanol vapor has induced an improvement in electrical conductivity of these materials. Remarkably, the sheet resistance dropped nearly three times for lignin biocarbon treated with isopropanol vapors. The use of isopropanol vapor annealing has increased sp² carbon and decreased oxygenated functionality contents of these biocarbons. These chemical changes were confirmed by X-ray photoelectron and Raman spectroscopy analyses. Transmission electron microscopy images revealed the formation of graphitic domains on samples pyrolyzed in the presence of isopropanol, while electron energy loss spectroscopy mapping at a nanoscale showed an increase in graphitic characteristics of the particles. These chemical and structural changes of biocarbons have improved their electrical conductivity and decreased sheet resistance values of conductive tracks prepared with such materials. As a proof of concept, we fabricated flexible electronic circuits and paper-based electrochemical devices using conductive lignin-based inks prepared with our method.