Preparation，energy harvesting and self-powered sensing application of PDA/rGO hydrogel

The traditional power supply methods have limited the rapid development of wearable electronic devices, and directly collecting energy from the surrounding environment is considered as the most promising way of energy supply. In this paper, polydopamine/reduced graphene oxide (PDA/rGO) hydrogel was successfully prepared by reducing graphene oxide (GO) with dopamine (DA) and water bath heating. In the rheological analysis, it is observed that the energy storage modulus (G') of the sample is significantly larger than its energy consumption modulus (G''), indicating a gel state structure. By analyzing its swelling behavior, adhesion, and self-healing properties, it is found that the prepared hydrogels exhibit good swelling behavior in both water and NaCl solution, with a swelling ratio of up to 900% in water. The presence of PDA enables the hydrogels to possess good self-adhesion and self-healing abilities. Further studies on its self-powered and sensing properties reveals that the PDA/rGO hydrogel swollen in NaCl solution can generate significant electrical output under external pressure, and the output current and voltage increases with the increase of NaCl solution concentration and external pressure. In an environment of a 0.05 mol/L NaCl solution subjected to a pressure of 10g, the mean output current and voltage measurements were recorded at 0.40 μA and 0.54 mV, respectively. Moreover, its resistance also showed a sensitive response to changes in external pressure. These results indicate that the PDA/rGO hydrogel has potential application in the fields of energy harvesting and self-powered sensing.