Spatially Confined Electrosynthesis of Halogen‐Poor and Carbonyl‐Rich Graphene for Boosting Water Desalination and Water Splitting

Abstract Electrochemical in situ modification of graphene remains a challenge because of the pretty low concentration of radicals generated during the electroexfoliation process. The spatially confined electrosynthesis of halogen‐poor and carbonyl‐rich graphene (XCG, X═F, Cl, Br) is reported. It is found that the effective radical addition reaction between graphite/graphene and electro‐generated radicals (halogen radical and carboxylic radical) is promoted by using X ⁻ and HCOO ⁻ as both intercalation ions and co‐reactants, which assists the efficient formation of high crystalline XCG. The assembled XCG membrane exhibited high interception for NaCl, KCl, MgCl ₂ , and K ₂ SO ₄ due to the narrow interlayer space. Theoretical calculations revealed favorable water migration on surface of F atoms, thus grasping the high water permeation. Furthermore, the halogen and carboxyl functional groups afforded XCG highly efficient water splitting. The current work highlights the in situ modification of graphene during the electroexfoliation process and the subsequent applications in membrane science, molecular engineering, and other energy‐related applications.