Interfacial Charge-Modulated Multifunctional MoS₂/Ti₃C₂T_x Penetrating Electrode for High-Efficiency Freshwater Production

Abstract

Freshwater production is critical in terms of solving the global water shortage. Aiming at improving freshwater production capability and ensuring its quality, an interfacial charge-modulated MoS 2 /Ti 3 C 2 T x -modified carbon fiber (CF/ MoS 2 /Ti 3 C 2 T x ) penetrating electrode is designed. To maximize the desalination and degradation efficiencies of CF/MoS 2 /Ti 3 C 2 T x , a photocatalytic component is introduced into the membrane capacitive deionization (PMCDI) device. High desalination capability is derived from the lamellar architecture structure of MoS 2 /Ti 3 C 2 T x . Meanwhile, excellent degradation performance is due to the formation of two photoelctrocatalytic activity centers, directionally generating singlet oxygen ( 1 O 2 ) and hydroxyl radical ( • OH). The intercalated Cl − (desalination) as the electron transfer bridge optimizes the charge distribution of MoS 2 /Ti 3 C 2 T x , reinforcing the photoelectrocatalytic activity (degradation). The formation of the electron-deficient (desalination) and electron-rich (regeneration) regions at the terminated O atom of Ti 3 C 2 T x accelerate the generations of • OH and 1 O 2 , respectively. In perspective, a mutual promotion process of desalination and degradation is achieved for high-efficiency production of high-quality freshwater. KEYWORDS: penetrating electrode, Ti 3 C 2 T x MXene, MoS 2 , membrane capacitive deionization, freshwater production

MXene‐Based Capacitive Deionization–Strong Competitor Among Faradaic Electrode Systems: Current Status and Future Perspectives

“…On the other hand, desalination metrics of the MXene/TMDs, particularly VS 2 /V 2 CT x [200] and CF/MoS 2 /Ti 3 C 2 T x [202] are much superior to the TMDs containing other Faradaic electrodes (Table 1, S2). An excellent SAC of the VS 2 /V 2 CT x electrode (166.8 mg g −1 ) is even the largest SACs achieved by MXene‐based desalination system (Table 1) and amongst a few high performance Faradaic electrodes (Table S2).…”

“…An excellent SAC of the VS 2 /V 2 CT x electrode (166.8 mg g −1 ) is even the largest SACs achieved by MXene‐based desalination system (Table 1) and amongst a few high performance Faradaic electrodes (Table S2). Moreover, simultaneous removal of the salt as well as organic dye with CF/MoS 2 /Ti 3 C 2 T x opens a new opportunity to achieve high quality fresh water [202] …”

“…Despite significant developments in the MXene-based desalination, its practical utility is still far from the real world where RObased desalination is one of the major choices. There are some recent progress in which the desalination performance of MXene-based CDI systems is extended to the real water samples [170,183,202] and large sized device test. [210] Therefore, we can propose the following points-of-care towards practical implications:…”

“…[201] Therefore, development of an electrode system which can simultaneously desalinate salt and photo-catalytically degrade contaminants from polluted salty water is a challenging task due to the mutual interference of both processes. Recently, Qie et al [202] designed a water penetrating CF/MoS 2 /Ti 3 C 2 T x electrode (interlayer spacing: 16 Å) to assemble single and multistage PMCDI devices (reactor wall of quartz window as a photocatalytic component). Under the simultaneous operation of desalination and degradation in the single-stage PMCDI, the SAC/ASAR of CEM-based PMCDI is found to be as high as 128.23 mg g À 1 / 12.82 mg g À 1 min À 1 .…”

Vertically Aligned Bismuthene Nanosheets on MXene for High-Performance Capacitive Deionization

“…Recent studies have shown that Cu metal can serve as a precursor to prepare bismuthene by a simple and efficient galvanic replacement reaction . Meanwhile, rationally designing heterostructures has been considered as one of the promising candidates to alleviate the restacking problem of two-dimensional materials. ,,, As far as we know, the direct application of residual Cu-decorated MXene to in situ construct bismuthene/MXene heterostructures has not been reported and hence deserves further exploration in the capacitive deionization field.…”