Self-Sustained Visible-Light-Driven Electrochemical Redox Desalination

Abstract

The freshwater scarcity and reducing energy demand are two challenging global issues. Herein, we propose a new route for desalination, self-sustained visible-light-driven electrochemical redox desalination. We propose a novel device architecture involving internal integration of quasi-solid-state dye-sensitized solar cell and continuous redox flow desalination with a bi-functional platinized-graphite-paper electrode. Both solar cell and redox flow desalination units are integrated by the bi-functional electrode with one side facing solar cell operating as a positive electrode and the other side facing the redox flow desalination unit operating as a negative electrode. The solar cell contains a gel-based tri-iodide/iodide redox couple and sandwiched between N719 dye modified photoanode and cathode. In contrast, the redox flow desalination consists of re-circulating ferro/ferricyanide redox couple sandwiched between the anode and cathode with two salt streams located between these electrodes. The performances of bi-functional electrodes in both redox couples were thoroughly investigated by electrochemical characterization. The brackish feed can be continuously desalted to freshwater level by utilizing the visible light illumination. As a device, this architecture combines energy conversion and water desalination. This concept bypasses the need for electrical energy consumption for desalination, which provides a novel structural design using photo-desalination to facilitate the development of self-sustained solar desalination technologies.