Tailoring morphological and chemical contributions of nanoscale charge transfer for enhanced triboelectric nanogenerators.

Triboelectric devices, operating through contact electrification (CE) and electrostatic induction, have shown great promise in energy harvesting applications. However, optimizing charge transfer at the interface remains crucial for enhancing device performance. This study introduces a novel approach to harnessing CE by employing morphological and chemical modifications of polymers. Our strategy involves adjusting the elastomer base to curing agent ratio to fine-tune the chemical properties of polydimethylsiloxane (PDMS) and introducing morphological modifications through a peeling and flipping (P/F) process of PDMS off the Si-substrate. Unlike conventional methods, the P/F-method minimally alters the intrinsic properties of PDMS, creating nanoscale surface corrugations adiabatically. We explore the mechanical, tribological, and electrical properties of the surface at the nano-scale and demonstrate that our approach allows for precise control of energy dissipation and electric potential at the surface, thereby optimizing charge transfer. Furthermore, we show that using a plasma-treated Si-substrate can further increase device performance up to 80% without affecting other properties. This study presents a comprehensive strategy for fine-tuning CE to enhance the performance of triboelectric nanogenerators.

Influence of MXene Composition on Triboelectricity of MXene-Alginate Nanocomposites.

MXenes are highly versatile and conductive 2D materials that can significantly enhance the triboelectric properties of polymer nanocomposites. Despite the growing interest in the tunable chemistry of MXenes for energy applications, the effect of their chemical composition on triboelectric power generation has yet to be thoroughly studied. Here, we investigate the impact of the chemical composition of MXenes, specifically the Ti3CNTx carbonitride vs the most studied carbide, Ti3C2Tx, on their interactions with sodium alginate biopolymer and, ultimately, the performance of a triboelectric nanogenerator (TENG) device. Our results show that adding 2 wt % of Ti3CNTx to alginate produces a synergistic effect that generates a higher triboelectric output than the Ti3C2Tx system. Spectroscopic analyses suggest that a higher oxygen and fluorine content on the surface of Ti3CNTx enhances hydrogen bonding with the alginate matrix, thereby increasing the surface charge density of the alginate oxygen atoms. This was further supported by Kelvin probe force microscopy, which revealed a more negative surface potential on Ti3CNTx-alginate, facilitating high charge transfer between the TENG electrodes. The optimized Ti3CNTx-alginate nanogenerator delivered an output of 670 V, 15 µA, and 0.28 W/m2. Additionally, we demonstrate that plasma oxidation of the MXene surface further enhances triboelectric performance. Due to the diverse surface terminations of MXene, we show that Ti3CNTx-alginate can function as either tribopositive or tribonegative material, depending on the counter-contacting material. Our findings provide a deeper understanding of how MXene composition affects their interaction with biopolymers and resulting tunable triboelectrification behavior. This opens up new avenues for developing flexible and efficient MXene-based TENG devices.