Modulating spatial charge distribution of lignin for eco-friendly and recyclable triboelectric nanogenerator

Tailoring the spatial charge distribution of triboelectric materials highly determines the distributed energy harvesting efficiency of triboelectric nanogenerators (TENGs). Herein, transition metal (iron) ions coordinated alkali lignin was successfully demonstrated as the high-performance tribopositive nanofiller in biodegradable carboxymethyl cellulose (CMC) to construct biodegradable TENGs. Arising from the expanded electron cloud on lignin skeleton and reinforced tribopolarity induced by the conjunction interaction between foreign iron ions and aromatic ring on lignin, the optimized TENG delivers an Voc of 110 V, Isc of 8.97 µA, Qsc of 15.3 nC and maximum output power density of 147.19 mW/m2 under contact frequency of 1 Hz owing to the improved electron transfer between the counter electrodes. Furthermore, such green biofilm presented excellent water soluble and recyclable features in accompanied with stable output signals when suffering from cutting-reforming process at least 5 times due to the presence of abundant dynamic reversible non-covalent bonds. The discovery of extraordinary tribopositive behavior of the lignin as nanofiller may pave the way of eco-friendly TENGs with boosting triboelectric output performances for self-powered sensing or mechanical energy harvesting.