An Ultrathin Flexible 2D Membrane Based on Single‐Walled Nanotube–MoS₂ Hybrid Film for High‐Performance Solar Steam Generation

Abstract

Solar steam generation is achieved by localized heating system using various floating photothermal materials. However, the steam generation efficiency is hindered by the difficulty in obtaining a photothermal material with ultrathin structure yet sufficient solar spectrum absorption capability. Herein, for the first time, an ultrathin 2D porous photothermal film based on MoS 2 nanosheets and single-walled nanotube (SWNT) films is prepared. The as-prepared SWNT-MoS 2 film exhibits an absorption of more than 82% over the whole solar spectrum range even with an ultrathin thickness of ≈120 nm. Moreover, the SWNT-MoS 2 film floating on the water surface can generate a sharp temperature gradient due to the localized heat confinement effect. Meanwhile, the ultrathin and porous structure effectively facilitates the fast water vapor escaping, consequently an impressively high evaporation efficiency of 91.5% is achieved. Additionally, the superior mechanical strength of the SWNT-MoS 2 film enables the film to be reused for atleast 20 solar illumination cycles and maintains stable water productivity as well as high salt rejection performance. This rational designed hybrid architecture provides a novel strategy for constructing 2D-based nanomaterials for solar energy harvesting, chemical separation, and related technologies.

Harnessing Solar‐Driven Photothermal Effect toward the Water–Energy Nexus

“…However, most wide-bandgap semiconductors exhibit relatively narrow absorption wavelength. Recently, owing to the fast development of nanotechnology, some emerging 2D semiconductors materials, e.g., MoS 2 , [54,55] MXene, [56] and black phosphorus, [57,58] are similarly utilized as photothermal materials because of their large surface area and strong light absorption ability. [46] To extend its absorption wavelength, black TiO x nanoparticle was successfully constructed through magnesium (Mg) reduction of white P25 TiO 2 nanocrystals to reduce its bandgap.…”

Solar‐Inspired Water Purification Based on Emerging 2D Materials: Status and Challenges

“…In this part, we mainly summarize the recent development of 2D materials for enhancing the absorption and PTCE. The specific strategies for strong absorption mainly includes hybrid design, phase transition, defect modulation, combination of plasmonic and all‐dielectric properties, and introduction of intermediate band (IB) states in alloying materials . To convert the light energy to heat efficiently, the high PTCE of 2D materials is needed.…”

“…For photothermal evaporation, a film with high mechanical stability is expected and thus the pure MoS 2 NSs could not satisfy this need. Combining with single‐walled carbon nanotubes (SWCNTs), Yang et al designed and fabricated an ultrathin porous evaporation film with high performance in solar light absorption, mechanical stability, thermal transport, and water permeability (Figure a) . The choice of SWCNTs is because of its high mechanical strength, super thermal transport ability, and hydrophobic nature.…”

“…a) Fabrication process of SWCNT‐MoS 2 system . Reproduced with permission Copyright 2018, WILEY‐VCH b1) Photograph and b2) SEM image of the fabricated MoS 2 ‐cotton cloth membrane . Reproduced with permission .…”

“…The hydrothermal self‐growth method is normally used for preparing MoS 2 . Chou et al fabricated the MoS 2 using a chemical exfoliation method and investigated its photothermal performance .…”