Proton-Conducting Polyelectrolyte Membranes Containing Graphene Dots for Moisture Electric Generators

Polyelectrolyte membranes used in moisture-electric generators (MEGs) typically face the challenge of producing high voltage but low current. In this study, a PSSA/PVA/GDs membrane (PPGM) was developed by incorporating graphene dots (GDs) into the poly(styrene sulfonic acid) (PSSA) and poly(vinyl alcohol) (PVA) composite system. The abundant oxygen-containing groups in GDs enhance hydrogen bonding and increase the cross-linking density, thereby improving the tensile strength of the PPGM to 25.77 MPa. Additionally, GDs endow the polyelectrolyte membrane with excellent hydrophilicity and a notable self-healing capability. The uniform dispersion of GDs, coupled with their excellent electrical properties, facilitates the formation of rapid proton transport channels, which, in turn, enhances the ionic conductivity to 1.41 S/m. Under a relative humidity (RH) of 83%, the membrane (1 cm2) can deliver an open-circuit voltage (VOC) of 0.31 V and a high short-circuit current (ISC) of 23 μA, and the high electric current (approximately 23 μA) can be sustained for up to 120 min. The current output performance of this membrane exceeds that of the pristine PSSA/PVA membrane, and this work is anticipated to advance the application of a traditional polyelectrolyte membrane in the field of MEGs.