Dyeing-Inspired Sustainable and Low-Cost Modified Cellulose-Based TENG for Energy Harvesting and Sensing

A combination of a triboelectric nanogenerator (TENG) and natural wood presents a sustainable approach toward a smart home due to the wood's biodegradability, low cost, and abundant resource. Major challenges for achieving a cellulose-based TENG are the brittleness, low crystallinity, and low surface charge density. We demonstrated a facile method to process and modify natural wood to satisfy application requirements. The treated wood has both good flexibility and tensile mechanical properties. After pressing, its crystallinity also saw a big increase, with the figure almost tripled. A further surface modification was inspired by dyeing technology. The cellulose on the surface of wood was cationically modified by 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC) via the solution-immersion method. After modification, the surface potential increased two times compared to that of the unmodified one. Density functional theory was used to calculate the absorption energy between cellulose molecules and CHPTAC to further verify the feasibility of the chemical modification. Larger differences between the two tribo-layers in terms of the energy level produce a high electrostatic charge flow. The modified pressed wood-based TENG can generate a peak current of 9.74 μA, a voltage of 335 V, and a transferred charge density of 71.45 μC/m2 through contact electrification. A concept of a self-powered and sensing smart floor integrated with this modified cellulose-based TENG was further developed to provide real-time motion monitoring for a smart home. This work not only removes the wood brittleness but also puts forward a novel method to improve the wood surface charge density from an interdisciplinary perspective, which is crucial to facilitate the application of natural wood in the nanogenerator area.