Recently, several reports have demonstrated that a moving droplet of seawater or ionic solution over monolayer graphene produces an electric power of about 19 nW, and this has been suggested to be a result of the pseudocapacitive effect between graphene and the liquid droplet. Here, we show that the change in the triboelectrification-induced pseudocapacitance between the water droplet and monolayer graphene on polytetrafluoroethylene (PTFE) results in a large power output of about 1.9 μW, which is about 100 times larger than that presented in previous research. During the graphene transfer process, a very strong negative triboelectric potential is generated on the surface of the PTFE. Positive and negative charge accumulation, respectively, occurs on the bottom and the top surfaces of graphene due to the triboelectric potential, and the negative charges that accumulate on the top surface of graphene are driven forward by the moving droplet, charging and discharging at the front and rear of the droplet.
Keywords: energy harvesting; graphene; polytetrafluoroethylene; triboelectric effect; water droplet.