The influence of functional groups on the triboelectric properties of chitosan derivatives and the electron transfer mechanism of insulators

Biomass-based triboelectric nanogenerators (TENGs) have become a research hotspot in biomedicine and wearable devices. This work reports five distinct chitosan (CS) derivatives modified with specific functional groups as triboelectric positive materials. The influence of surface roughness, dielectric properties, and hydrogen bond structures on the performance of TENGs is assessed. Chitosan quaternary ammonium salt (CQAS) exhibits outstanding triboelectric performance, with an open-circuit voltage of 157 V, a short-circuit current of 2.7 μA, and a transferred charge density of 3.0 nC/cm². The CQAS exhibits significantly enhanced surface roughness, surface potential and mechanical properties. Notably, its dielectric constant has surged 37 times compared to CS, and the maximum strain has increased by 43.9 %. Density functional theory was employed to calculate the tribo-material's band gap and orbital energy levels, proposing a new electron transfer mechanism for insulators. Furthermore, molecular dynamics simulations confirmed a negative correlation between the material's number of hydrogen bonds and the TENG's transferred charge density while showing a positive correlation with mechanical properties. This study elucidates the correlation between molecular structures with diverse functional groups and their macroscopic properties, providing theoretical guidance to improve energy conversion efficiency and broaden the application of biomass materials in TENGs.