In-situ desalination-coupled electrolysis with concurrent one-step-synthesis of value-added chemicals

초록

An efficient multi-functional electrolyzer with a Ni-and Fe-layered double hydroxide (NiFe-LDH) anode and a binary NiMo cathode is designed for overall water splitting coupled with the desalination of saline water and production of value-added chemicals. The NiFe-LDH and NiMo pairs separated by a bipolar membrane (BPM) show overpotentials as low as those of noble metal catalysts for oxygen and hydrogen evolution reactions in 1 M KOH and 1 M H2SO4 solutions, respectively. Arraying anion and cation-exchange membranes (AEMs and CEMs, respectively) with BPMs (NiFe-LDH/BPM/[AEM/CEM]n/BPM/NiMo; n = 1 or 5) further enables the desalination of brackish water and seawater at specific energy consumption of 1.8 kWh m(-3), with concurrent production of HCl and NaOH. The Faradaic efficiencies of the device for O2 and H2 production are >95 % at J = 100 mA cm-2 over 20 h, while the initial pH values of the anolyte and catholyte remain unchanged. Detailed surface char-acterization of the electrocatalysts is performed, and various electrolyzer configurations are compared in nterms of desalination efficiency.

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