A solar desalination charger for water treatment and value-added chemical production

Abstract

This study presents a photoelectrocatalytic desalination charger for the remediation of aquatic pollutants and the production of value-added chemicals. Under 1 sun irradiation, a Co-WBVO (BiVO4 doped with W and deposited with CoOOH) photoelectrode and aqueous NaxC electrode (Na on carbon felt, NaxC) pair efficiently desalinates brackish water (0.171 M NaCl) through ion-exchange membranes at an ion transport efficiency of ∼100%. The desalted chloride is partially oxidized by photogenerated holes into reactive chlorine species (RCSs) at a faradaic efficiency (FE) of >90%. The in situ generated RCSs are actively involved in the sequential oxidation of As(III) and NH4+. Meanwhile, the desalted Na+ is rapidly inserted into NaxC without any accumulation. Upon coupling with the charged NaxC, the electrocatalytic production of H2O2via O2 reduction with carbon nanotubes, H2via H2O reduction with NiMoS, and HCOOH via CO2 reduction with porous Bi are achieved at FEs of >80%. The as-designed PEC hybrid of the proof-of-concept can be applied to various purposes, including desalination, seawater electrolysis, production of value-added chemicals, and energy storage.