Direct Writing and Printing of Surface and Interface Modified Cellulose for Friction Nanogenerators

Abstract In recent years, cellulose has garnered substantial attention in the realm of triboelectric nanogenerator (TENG) fabrication, owing to its commendable biodegradability and reproducibility. Nevertheless, the limited surface polarity and insufficient surface functional groups have imposed significant constraints on its evolution towards high-performance TENGs. In this study, nanocellulose (CNFs) was harnessed as the friction layer material for the friction nanogenerator, while the surface interface underwent chemical treatment to introduce two distinct functional groups, namely -NH2 and -F. Beyond scrutinizing the physical and chemical attributes of these functionally modified cellulose variants, the functionalized CNFs were also employed in TENGs to explore their impact on the electron gain/loss capacity or polarity enhancement of CNFs. Simultaneously, the enhanced surface interfaces of CNFs facilitated the amelioration of the electrical output performance in TENGs. Our findings unveil that the utmost degree of cationic charge was achieved at a mass ratio of 2.0 between epoxy propyl trialkylamine chloride (EPTMAC) and cellulose. Furthermore, the incorporation of -F, facilitated by nano SiO2 and PFOTS, not only rendered the water contact angle of FCNF-SiO2 aerogel superhydrophobic at 150°, but also yielded the highest output voltage at a mass ratio of 3.0 between dried fiber and nano SiO2. These outcomes unequivocally underscore the incomparable advantages and practical value of CNFs in the domain of environmentally friendly mechanical energy harvesting systems, specifically TENGs.