Transforming Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> MXene's intrinsic hydrophilicity into superhydrophobicity for efficient photothermal membrane desalination.

Zhang, Baoping; Wong, Pak Wai; Guo, Jiaxin; Zhou, Yongsen; Wang, Yang; Sun, Jiawei; Jiang, Mengnan; Wang, Zuankai et al. · Nat Commun · 2022

basic_science · Level V

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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.