Deep eutectic solvent-modified sulfonated silk nanofibers for hydrogel moisture electric generators in energy...

Moisture such as water vapor in the natural environment contains abundant energy. Moisture-enabled electricity generators (MEGs) provide a new method for efficiently utilizing the energy contained in moisture. However, conventional hydrogels exhibit poor moisture-electricity generation performance due to the lack of efficient protonation or ion diffusion. In this work, silk was prepared into sulfonated silk nanofibers (SSNFs) through chemical-physical pretreatment using a deep eutectic solvent (DES) system. A silk nanofiber-based hydrogel MEG was designed by integrating SSNFs and LiCl into a polyacrylamide (PAM) hydrogel matrix using a deionised water (DI water) and glycerol (GLY) binary solvent system. Owing to the introduction of SSNFs, the moisture absorption rate of the hydrogel was increased to 66.3%, and the fracture strength was improved by 74%. The assembled SS-HMEG device could generate electricity spontaneously over a wide relative humidity (RH) range from 45% to 85%. The results showed that the SS-HMEG device achieved an open-circuit voltage (Voc) of 1.19 V and a short-circuit current (Isc) of 59.2 μA at 85% RH. Notably, it could still maintain a voltage output above 0.95 V at a low temperature of -20 °C. The SS-HMEG could be easily scaled up: series integration of 40 units yielded a system output voltage of 38.22 V, which could drive a commercial humidity sensor to operate continuously. This work opens a new avenue for SNF applications in new energy, offering a feasible strategy for green and sustainable energy technologies.