Preparation of Chitin Nanofibers and Natural Rubber Composites and Their Triboelectric Nanogenerator Applications.

Triboelectric nanogenerators (TENGs) have gained significant attention as promising energy-harvesting devices that convert mechanical energy into electrical energy through charge separation induced by friction and electrostatic induction. In this study, we explore the utilization of biowaste shrimp shell-extracted chitin nanofiber (ChNF) as a viable eco-friendly material for TENG applications. Composite materials were prepared by incorporating ChNF into natural rubber (NRL) at loading levels of 0.1 and 0.2 wt% (NRL/ChNF) to form the TENG triboelectric layer. ChNFs with a uniform width of approximately 10-20 nm were successfully extracted from the shrimp shells through a simple mechanical procedure. The NRL/ChNF composites exhibited enhanced mechanical properties, as evidenced by a higher Young's modulus (3.4 GPa) compared to pure NRL. Additionally, the NRL/ChNF composites demonstrated an increased dielectric constant of 3.3 at 0.1 MHz. Moreover, the surface potential difference of NRL increased from 0.182 V to 1.987 V in the NRL/ChNF composite. When employed as the triboelectric layer in TENG, the NRL/ChNF composites exhibited significant improvement in their output voltage, with it reaching 106.04 ± 2.3 V. This enhancement can be attributed to the increased dielectric constant of NRL/ChNF, leading to enhanced charge exchange and charge density. This study presents a straightforward and environmentally friendly technique for preparing sustainable natural materials suitable for energy-harvesting devices.

Carbon nanotube/polydimethylsiloxane composite micropillar arrays using non-lithographic silicon nanowires as a template for performance enhancement of triboelectric nanogenerators.

Carbon nanotube/polydimethylsiloxane composite micropillar (CNT/PDMS MP) arrays were successfully fabricated using non-lithographic silicon nanowire (SiNW) arrays as a template for performance enhancement of triboelectric nanogenerators (TENG). The CNT/PDMS MP arrays were obtained by pouring CNT/PDMS composites on the SiNW arrays and peeled off. Surface topology of CNT/PDMS composites directly depends on morphology of SiNW arrays, which can be varied by the etching time of the typical metal-assisted chemical etching process. The micropatterned CNT/PDMS composites was mostly depicted to the SiNW array template pattern when the morphologies of the SiNW were optimized with a length of approximately 10 mm. Next, the CNT/PDMS MP arrays were utilized as a triboelectric layer of TENGs, generating the maximum output voltage of 22.84 ± 0.85 V, enabling an approximately 18-fold improvement in an electrical output compared to the flat PDMS-based TENG. The performance enhancement of TENGs based on CNT/PDMS MP arrays are attributed to synergic effects of (1) an enhancement of electrostatic induction by CNT composites, increasing dielectric constant, and (2) an enhancement of electrification by surface texturing using non-lithographic pattern and CNT composites.