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

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 characterization of the electrocatalysts is performed, and various electrolyzer configurations are compared in terms of desalination efficiency.

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Published in: Desalination
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.desal.2023.116431