Capacitive Deionization of Saline Water by Using MoS₂–Graphene Hybrid Electrodes with High Volumetric Adsorption Capacity

Abstract

Capacitive deionization (CDI) has received wide attention as an emerging water treatment technology because of its low energy consumption, low cost, and high efficiency. However, the conventional carbon electrode materials for CDI have low densities, which occupy large volumes and are disadvantageous for use in limited space (e.g., in household or on offshore platforms). In order to miniaturize the CDI device, it is quite urgent to develop high volumetric adsorption capacity (VAC) electrode materials. To overcome this issue, we rationally designed and originally developed high VAC MoS2–graphene hybrid electrodes for CDI. It is interesting that MoS2–graphene hybrid electrode has a much higher NaCl VAC of 14.3 mg/cm3 with a gravimetric adsorption capacity of 19.4 mg/g. It has been demonstrated that the adsorption capacity is significantly enhanced because of the rapid ion transport of MoS2 and high electrical conductivity of graphene. In situ Raman spectra and high-angle annular dark-field scanning transmission electron microscopy tests demonstrated a favorable Faradaic reaction, which was crucial to enhancing the NaCl VAC of the MoS2–graphene hybrid electrode. This work opens a new avenue for miniaturizing future CDI devices.

Reversible adsorption and desorption of PFAS on inexpensive graphite adsorbents via alternating electric field

“…Carbonaceous adsorbents 39,40,[44][45][46] (e.g., activated carbon, graphene, carbon nanotubes) are attractive due to their chemical durability and thermal stability, 47 and a large specic surface area that can accelerate the adsorption kinetics. 48 However, most carbonaceous adsorbents exhibit a relatively low adsorption capacity (i.e., the amount of contaminant taken up by the unit mass of adsorbent) 49 for PFAS with a short uoroalkyl chain length. [50][51][52][53][54] Further, these absorbents oen suffer from a decrease in the adsorption capacity over time because the residual PFAS remains even aer the regeneration process.…”

α-Fe2O3/graphene oxide powder and thin film nanocomposites as peculiar photocatalysts for dye removal from wastewater

“…In fact, graphene is considered an important material in wastewater treatment technologies because of its outstanding features 3 , 21 , 22 . Up to now, graphene and its derivatives are used as a matrix of metal/metal oxide materials to enhance the catalytic performance of materials, including Ni 19 –NiO 23 for dye-synthesized solar cell, CuO 24 for catalysts, Pd–Ag 25 and AuNPs/MoS 2 26 for the electrochemical sensor, TiO 2 27 and MoS 2 28 for electrode, AgBr 29 and Fe 3 O 4 30 for water purification, or water splitting 19 . Yuan et al suggested a new mechanism for the improvement of photocatalytic activities with graphene.…”

Exploration of Energy Storage Materials for Water Desalination via Next-Generation Capacitive Deionization

“…MoS 2 as CDI electrode cannot give a satisfactory performance, possibly due to the poor conductivity and low accessible active sites. Shortly afterward, various low dimensional nanomaterials such as CNT (Srimuk et al, 2017), graphene (Han J. L. et al, 2019;Peng et al, 2020), or g-C 3 N 4 (Tian et al, 2020) were employed to further improve the performance of MoS 2 .…”