Achieving a highly efficient chitosan-based triboelectric nanogenerator via adding organic proteins: Influence of morphology and molecular structure

The utilization of biodegradable materials for the triboelectric nanogenerator (TENG) has provoked intensive interest since the growth of electronic devices tended to operate in proximity of the human body. This work proposed highly efficient biopolymer, based on a chitosan (CS) TENG, by incorporating protein-based compounds as fillers. The effect of different types of protein; albumin, egg-shell membrane (ESM) and silk fiber (SF), with the loaded content on the output performance of TENG was explored. It was found that the output signal can be maintained and even enhanced by embedding interlaced-fiber and making a gauze-like structure inside the CS matrix. Morphologies not only have different types of amino acid side chains, but also affect triboelectric output performance. High content of glycine, alanine and serine consequently increases the output signal by providing additional charges from molecular polarizations. Mixing glycine amino acid in the presence of alanine and serine reduces the centrosymmetric structure of the host amino acid and creates polar domains. Adding SF in CS, therefore, achieves the best output voltage (VOC) and current (ISC) as compared to other additives. The CS/SF TENG, with 10 wt% SF added, can reach - 77 V and - 13 mu A of VOC and ISC, respectively. Its maximum output power of - 202 mu W, with power density of 22.4 mu W/cm2, is 6 times higher than that from pristine CS TENG, which can easily light up 59 light emitting diodes (LEDs) connected in series. Finally, the biodegradability was confirmed at various weeks related to the output measurement of VOC and ISC. After 9 weeks of the soil burial test, the CS/SF still generated similar to 20 V VOC and similar to 2.5 mu A ISC with 30% weight loss.