Capacitive deionization (CDI) features a low-cost and energy-efficient desalination approach based on electrosorption of saline ions. To enhance the salt electrosorption capacity of CDI electrodes, we coat ion-selective pseudocapacitive layers (MnO and Ag) onto porous carbon electrodes (activated carbon cloth) with only minimal use of a conductive additive and a polymer binder (<1 wt % in total). Optimized pseudocapacitive electrodes result in excellent single-electrode specific capacitance (>300 F/g) and great cell stability (70% retention after 500 cycles). A CDI cell out of these pseudocapacitive electrodes yields as high charge efficiency as 83% and a remarkable salt adsorption capacity up to 17.8 mg/g. Our finding of outstanding CDI performance of the pseudocapacitive electrodes with no use of costly ion-exchange membranes highlights the significant role of a pseudocapacitive layer in the electrosorption process.

In search of a practical alternative catalyst to costly and rare noble metals for hydrogen evolution reaction (HER), here we propose a lamellar electrode architecture out of engineered 2D MoS 2 platelets that are stable in harsh electrochemical conditions, densified in the catalytically active sites, and enhanced in the interlamellar charge transfer. Energetic ion bombardment such as Ar ion beam milling (IBM) as a large-scale surface engineering technique can successfully create numerous edge states onto the MoS 2 lamella with an observable penetration depth of ∼10 nm for the first time, leading to an excellent onset overpotential of 33.3 mV at 0.1 mA/cm 2 . Interlamellar charge transfer enhancement by raising the metallic portion of 1T-phase MoS 2 and also by inserting conductive rGO platelets in the lamella turns out to improve the HER catalytic activity remarkably. The promising results obtained in an aqueous electrolyte with rarely reported 1 M LiOH imply a potential use in seawater splitting toward energy carrier storage. Equipped in a Li−water battery cell, our engineered MoS 2 lamella electrode reveals, for the first time, a remarkable discharge performance supplying >2.2 V stably for more than 2.5 days, lending it potential adaptability to energy storage systems such as battery and fuel cells.

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