An efficient multi-functional electrolyzer with an electrodeposited Ni- and Fe-layered double hydroxide (NiFe-LDH) anode and an electrodeposited NiMo cathode is designed for overall water splitting coupled with the desalination of saline water and production of acid and base solution. NiFe-LDH is characterized by abundant active sites for OH adsorption and an optimal binding energy for M-OH. Meanwhile, loading bimetallic NiMo on an active electrode for the HER has been known to improve the electrocatalytic activity and durability owing to its high surface area. 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. Thereafter, the electrode pair with an array of anion- and cation-exchange membranes (AEMs and CEMs) in alternatively stacking manner showed the desalination of brackish water and seawater at specific energy consumption of 1.8 kW h 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. The proposed multi-functional electrolyzer is highly promising for converting electrical energy into hydrogen energy, simultaneously desalinating saline water, and producing value-added chemicals. Subsequently, we compared electrodialytic performance over unit cell thickness, types of ion exchange membranes, and number of stacks in the device.This work is financially supported by Korea Water Cluster (KWC) as Korea Water Cluster ProjectLab. This work was supported by the Technology Innovation Program (or Industrial Strategic Technology Development Program-Alchemist Project) (NTIS-1415187362, 20025773, Development of building-Integrated Carbon Control Technologies) funded By the Ministry of Trade, Industry & Energy(MOTIE, Korea).
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