Research On The Surface And Interface Modified Cellulose Nanofibers Printed Triboelectric Nanogenerator

In recent years,cellulose has attracted extensive attention in the preparation of triboelectric nanogenerators（TENG）due to its good biodegradability and reproducibility.Cellulose based TENG was produced by combining natural polymer cellulose with TENG.The emergence of this green energy harvesting element not only opens the way for new green materials in the energy industry,but also brings more development potential to TENG.However,the weak surface polarity and insufficient surface functional groups greatly limit the development of high performance TENG.In this paper,nanocellulose（CNFs）was used as the friction layer material of the friction nanogenerator.The surface interface was modified by chemical treatment,and three groups-COOH,-NH₂and-F were introduced.In addition to analyzing the physical and chemical properties of three different kinds of functional cellulose,functionalized CNFs were also applied to TENG to study the effect of functionalized cellulose on improving the ability of gaining and losing electrons or polarity of CNFs.Meanwhile,surface interface modified CNFs can also improve the electrical output performance of TENG.It was found that tempo-oxidation and high pressure homogenization method could introduce-COOH,and with the increase of the amount of Na Cl O added,the degree of carboxylation of CNFs increased,and it tended to be more stable in water dispersion system.The positive friction layer aerogel prepared by direct writing printing（DIW）has a layered structure and uniform and continuous pores on the surface and inside,which has good mechanical properties.The performance of TENG assembled with PDMS was significantly improved.Especially when the amount of Na Cl O was 8mmol/g,the output voltage was 264V,and TENG had good cyclic stability.-NH₂ can be introduced using epoxypropyl trialkyl amine chloride（EPTMAC）.The degree of cationization of nanocellulose was controlled by changing the mass ratio of EPTMAC to cellulose.When the mass ratio of EPTMAC to cellulose was 2.0,the degree of cationization was the highest.The positive friction layer prepared by DIW has a thick lamellar structure,and the pores on the surface are significantly reduced and uneven.The thermal stability of cationized cellulose decreased.The performance of TENG assembled with PDMS was significantly improved.Especially when the mass ratio of EPTMAC to cellulose is 2.0,the output voltage is 273V,and TENG has good cyclic stability.-F can be introduced using nano Si O₂and PFOTS.The amount of F modified on the surface of Si O₂ microspheres under vacuum was adjusted by controlling the mass ratio of the dry fiber and Si O₂ microspheres.Si O₂microspheres were uniformly attached to the surface of FCNF-Si O₂ aerogel prepared by DIW.XPS results showed that the peak values of FCNF-Si O₂ aerogel at 290.4e V and292.5e V showed CF₂and CF₃,indicating that PFOTS was successfully grafted on the surface of Si O₂ particles.In addition,the maximum water contact Angle of FCNF-Si O₂aerogel is 150°,reaching the superhydrophobic state.When the mass ratio of TENG,dry fiber and Si O₂ microspheres assembled with PET board is 3.0,the output voltage reaches the maximum of 400V.Moreover,TENG has good circulation stability and hydrophobicity.