Moisture-driven electric power generation using graphene-based hydrogels for sustained power output and self-powered sensing

Abstract

Moist electric generators (MEGs) produce electric power from hydration gradients and have been identified as a promising sustainable technology for advanced energy systems. This article reports the fabrication of a graphene-templated poly(acrylic acid) (PAA) hydrogel MEG with a gradient distribution of PAA swelling resulting from variations in polymer confinement. The MEG delivers an open-circuit voltage of ~0.78 V for over 120 hours under ambient environmental conditions with a power density of 62 mW m⁻². The MEG effectively operates at temperatures as low as - 25 °C. A current output of 780 µA has been achieved through a parallel configuration of MEG elements, and an output of 18 V has been achieved using a series configuration. The electric output of the MEGs can be scaled and is shown to power various commercial electronics, including LEDs, an 8-digit calculator, and a humidity sensor with an LCD screen. Additionally, the MEG is shown to perform as a self-powered tactile sensor.