Transforming Ti3C2Tx MXene’s intrinsic hydrophilicity into superhydrophobicity for efficient photothermal membrane desalination

Abstract

Owing to its 100% theoretical salt rejection capability, membrane distillation (MD) has emerged as a promising seawater desalination approach to address freshwater scarcity. Ideal MD requires high vapor permeate flux established by cross-membrane temperature gradient (∆T) and excellent membrane durability. However, it’s difficult to maintain constant ∆T owing to inherent heat loss at feedwater side resulting from continuous water-to-vapor transition and prevent wetting transition-induced membrane fouling and scaling. Here, we develop a Ti3C2Tx MXene-engineered membrane that imparts efficient localized photothermal effect and strong water-repellency, achieving significant boost in freshwater production rate and stability. In addition to photothermal effect that circumvents heat loss, high electrically conductive Ti3C2Tx MXene also allows for self-assembly of uniform hierarchical polymeric nanospheres on its surface via electrostatic spraying, transforming intrinsic hydrophilicity into superhydrophobicity. This interfacial engineering renders energy-efficient and hypersaline-stable photothermal membrane distillation with a high water production rate under one sun irradiation.

Surface Modification, Topographic Design and Applications of Superhydrophobic Systems

“…Also, superhydrophobic surface with Cassie wetting state can be used as a substrate to prepare free-standing membrane or film due to its water repellent property. For example, Chen et al [142,143] described an electrochemical printing on superhydrophobic micropillar-structured substrates and successfully synthesized the free-standing metal-organic framework (MOF) and microcavity-patterned polymer film, respectively. They demonstrated that the obtained material film can be easily peeled from the substrate and transferred without adhesion.…”

“…The superhydrophobic materials can also participate in interface engineering involving phase and thermal transition reactions. Zhang et al [142] reported a strategy to transform hydrophilic MXene to superhydrophobic MXene for application in photothermal membrane desalination (MD). In their study, superhydrophobic interface engineering could address several drawbacks of traditional MD systems (Figure 7A), such as 1) conventional MD materials that are usually adopted comprise of commercial polyvinylidene fluoride membrane (C-PVDF).…”

“…The superhydrophobic materials can also participate in interface engineering involving phase and thermal transition reactions. Zhang et al [142] . reported a strategy to transform hydrophilic MXene to superhydrophobic MXene for application in photothermal membrane desalination (MD).…”

Two-Dimensional Selenium Nanosheet-Based Sponges with Superior Hydrophobicity and Excellent Photothermal Performance

“…Moreover, in 2020, Li et al [ 20 ] passivated 2D black phosphorus (BP) NSs with hydrophobic SiO 2 by hydrolytic co-condensation of 3-aminopropyl-triethoxysilane and tetraethoxysilane, which exhibited high efficiency and stability in solar evaporation without sacrificing the intrinsic properties of BP NSs. In the past decade, many researchers have focused on the superhydrophobic materials with high thermal efficiency and broad-spectrum light absorption to maximum the light-to-heat conversion [ 21 , 22 , 23 , 24 ]. As a typical kind of 3D materials, melamine sponge (MS) was widely used as a universal substrate in the fields of oil/water separation and solar desalination due to its large adsorption capacity, high stability, and low cost [ 25 , 26 ].…”

Cellulose-Based Photothermal Microspheres: A Sustainable Solution to Harvesting Freshwater Outdoor

“… − , Photothermal materials play a dominant role in solar absorption for evaporation. In the past, a higher absorption coefficient within the entire solar spectrum was the primary objective for designing new photothermal materials, such as plasmonic metal nanoparticles (e.g., AuNPs, AlNPs), ,− carbon materials (e.g., graphene, multi-walled carbon nanotubes), ,,− semiconducting materials, , conjugated polymers (e.g., polypyrrole, polyaniline), , and the transition metal carbide/nitride (MXene) − etc. The absorption coefficient and range of previously developed photothermal materials have already been very close to the absorptivity ceiling (≥99%, 200–2500 nm).…”