Redox-Mediator-Free Solar Desalination via Photoelectrochemical Water Oxidation

Addressing the critical global challenge of freshwater scarcity requires sustainable desalination technologies. The solar-driven photoelectrochemical (PEC) desalination offers promise, while performance is typically limited by current decay due to the increased Donnan potential and elevated resistance in the diluted channel. Here, we overcome this limitation through the oxygen evolution reaction (OER) achieved in an anode electrolytic chamber (AEC) and a photoelectrode employing BiVO4 to generate charge-separated electrons and holes. The holes use adsorbed water molecules, thus bypassing the consumption of sacrificial redox couples and achieving stable, continuous operation. To accelerate the reaction, we integrated a FeNiOx catalyst layer onto the BiVO4. This engineered system demonstrates exceptional operational stability, maintaining a constant current density for over 720 min while achieving a salt removal rate of 39.34 μg cm–2 min–1. This work opens a sustainable pathway of photoelectrochemical desalination without the consumption of electrolytes.