The solar-driven redox seawater desalination based on the stable and environmentally friendly WO3/BiVO4 photoanode

Abstract

Nowadays, stable photoelectrochemical seawater desalination is a challenge. In this work, an environmentally friendly WO3/BiVO4 photoanode is reported to achieve stable solar-driven redox desalination. The WO3/BiVO4 photoanode was prepared by the hydrothermal method and drop-casting and the cathode is the activated carbon coated on graphite paper. Within the desalination system, the I−/I3− redox species are recycled between anode/cathode chambers. In the short-circuit state, with illumination as the driving force, the salt removal rate of 65.03 μg/(cm2·min) is obtained without the electric consumption. During the desalination process, the energy output process can be implemented with a salt removal rate of 29.8 μg/(cm2·min) with constant current discharge. Importantly, the solar desalination system based on WO3/BiVO4 photoanode is quite stable. Within the five cycles, the variation of the salt removal rate is within 3.32 μg/(cm2·min). As the practical application, the seawater is desalted to the freshwater standard using the current system, in which the conductivity decreases to 0.96 mS/cm from 53 mS/cm. This work provides a feasible approach to developing stable and efficient solar-driven seawater desalination for long-term usage.