Sustainable power generation via hydro-electrochemical effects.

Recent efforts towards energy scavenging with eco-friendly methods and abundant water look very promising for powering wearables and distributed electronics. However, the time duration of electricity generation is typically too short, and the current level is not sufficient to meet the required threshold for the proper operation of electronics despite the relatively large voltage. This work newly introduced an electrochemical method in combination with hydro-effects in order to extend the energy scavenging time and boost the current. Our device consists of corroded porous steel electrodes whose corrosion overpotential was lowered when the water concentration was increased and vice versa . Then a potential difference was created between two electrodes, generating electricity via the hydro-electrochemical method up to an open-circuit voltage of 750 mV and a short-circuit current of 90 μA cm -2 . Furthermore, electricity was continuously generated for more than 1500 minutes by slow water diffusion against gravity from the bottom electrode. Lastly, we demonstrated that our hydro-electrochemical power generators successfully operated electronics, showing the feasibility of offering electrical power for sufficiently long time periods in practice.