Interfacial engineering of sucrose-derived dual-functionalized carbon for targeted ion capture in hybrid capacitive...

Desalination of abundant seawater into usable freshwater is an effective strategy to alleviate the crisis of freshwater resources. However, relying solely on Na⁺/Cl^- trapping electrode materials proves inefficient, and residual high concentrations of Cl^-/Na⁺ corrode the electrodes, compromising desalination performance and thus not constituting true desalination. To overcome these challenges, sucrose-derived porous activated carbon (SBC) is developed via rapid dehydration, pre‑carbonization, and high-temperature annealing for Na⁺ and Cl^- capture electrodes in hybrid capacitive deionization (HCDI) for seawater desalination. The Na⁺ capturing electrode was fabricated through in situ polymerization of MnO₂ on SBC (SBC@MnO₂), and the Cl^- capturing electrode was prepared by coating SBC with sodium-pre-intercalated MnO₂ combined with in situ polymerization of polypyrrole (SBC@Na_xMnO₂@PPy₁). Both electric double-layer capacitance and Faradaic pseudocapacitance primarily govern the ion adsorption and storage. Functionalized SBC exhibited enhanced specific capacitance, a notable desalination capacity (57.22 mg g^-1), and a remarkably high desalination rate (1.06 mg g^-1 s^-1). X-ray photoelectron spectroscopy analysis revealed that the primary adsorption mechanisms involved ion insertion associated with the redox reactions of the electrode materials and surface adsorption. Furthermore, this approach exhibited effective purification capabilities for seawater, river water, and rainwater, thereby expanding the potential application scope of the HCDI.