Graphene Oxide-Tuned MoS₂ with an Expanded Interlayer for Efficient Hybrid Capacitive Deionization

Abstract

Capacitive deionization (CDI) has shown great promise in desalinating salt water; however, conventional CDI electrode materials suffer from low specific salt capacity and charge efficiency owing to the co-ion expulsion effect. Herein, using expanded MoS 2 nanosheets supported by reduced graphene oxide (MoS 2 /rGO) as the intercalation electrode, we develop a hybrid CDI system that shows a battery-like behavior and can reversibly store cations through the intercalation mechanism. The incorporation of rGO in the composite not only affords a conductive support and ensures fast electron transfer but also, more importantly, widens the MoS 2 interlayer spacing from 0.62 to 0.73 nm. The expanded MoS 2 interlayer facilitates the diffusion of cations and decreases the internal strain during the intercalation/de-intercalation process. Also, it endows MoS 2 /rGO with more accessible sites and space for cations in the electrolyte. Benefiting from the desirable structure features, the hybrid CDI system delivers a remarkable specific salt capacity of 34.20 mg g −1 and a charge efficiency as high as 97% in 300 mg L −1 sodium chloride aqueous solution. The MoS 2 /rGO involved in the CDI system for the adsorption of other metal ions is also verified, indicating its potential applications for the removal of various metal ions in brackish water and seawater.

Designing Hybrid Mesoporous Pr/Tannate-Inbuilt ZIF8-Decorated MoS2as Novel Nanoreservoirs toward Smart pH-Triggered Anti-corrosion/Robust Thermomechanical Epoxy Nanocoatings

“…The TGA graph of the MS sample is consistent with the patterns reported in the literature. 22,37 As stated, the sintering-based degradation of MS sheets in a pure N 2 atmosphere can be recognized from 485 up to 800 °C with a mass loss of ca. 17%.…”

Recent progress in materials and architectures for capacitive deionization: A comprehensive review

“…Graphene and CNTs formed self-assembled network while CNTs and ZnO minimized agglomeration of pristine graphene sheets. The agglomeration of graphene sheets was also minimized by producing hierarchically hybrid nanostructure of carbon nanoparticles with graphene (Mohanapriya & Jha, 2019) and GO tuned MoS 2 (Gao et al, 2020). This strategy presented unique morphology and high specific surface area of the composite, thereby providing better electrosorption performance.…”

“…In another study, HCDI using expanded MoS 2 nanosheets supported on reduced graphene oxide (MoS 2 /rGO) as the intercalation electrode was developed (Gao et al, 2020, p. 2). The incorporation of rGO increased the conductivity and interlayer spacing of MoS 2 from 0.62 to 0.73 nm providing more accessible sites and space to diffuse cations in the electrolyte (Figure 9a).…”

“…(a) SEM images of MoS 2 /rGO; (b) salt removal data; (c) comparison of electrosorption capacities by MoS 2 and MoS 2 /rGO. Reprinted from Gao et al (2020), p. 2), copyright (2020), with permission from American Chemical Society…”

A Brief Review on High‐Performance Capacitive Deionization Enabled by Intercalation Electrodes

“…As a result, the HCDI system has demonstrated a high desalting capacity of 31.2 mg g −1 at 1.2 V in a 580 mg L −1 NaCl solution, which has realized significant improvement compared to that of the traditional CDI system (17.1 mg g −1 ). [ 53 ] Since then, various SII electrodes were proposed, many of which were initially explored in the context of energy storage, such as FeFe(CN) 6 (PB), [ 54 ] Na 4 Ti 9 O 20 (NTO), [ 55 ] NaTi 2 (PO 4 ) 3 (NTP), [ 56 ] Na 3 V 2 (PO 4 ) 3 (NVP), [ 57 ] Na 0.71 CoO 2 (NCO), [ 58 ] Na 0.7 MnO 2 (NMO), [ 59 ] polyaniline (PANI)‐tube‐decorated with Prussian blue (PB) nanocrystals (PB/PANI composite), [ 60 ] MnHCF, [ 61 ] MoS 2 /rGO [ 62 ] and Ti 3 C 2 T x ‐Mxene [ 63 ] etc.…”