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

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 Na_xC electrode (Na on carbon felt, Na_xC) 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 Na_xC without any accumulation. Upon coupling with the charged Na_xC, 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.