Self-assembly hierarchical binary gel based on MXene and montmorillonite nanosheets for efficient and stable solar steam generation.

Solar steam generation is an environment-friendly, low-cost, efficient and sustainable approach to produce fresh water, which has been widely researched recently as a promising technology. However, practical application of solar steam generation is always restricted by the photothermal conversion efficiency and long-term stability. Herein, the self-assembly hierarchical binary gel (HBG) containing a MXene (Ti 3 C 2) gel as the upper structure and montmorillonite (MMT) gel as based materials was designed to achieve the efficient solar desalination toward water purification applications. The result indicated that Ti 3 C 2 gel exhibited high light absorption efficiency (over 94%) in a wide solar spectrum range, meanwhile, MMT gel showed remarkable thermal isolation with a low conductivity of 0.04366 (W/m·K) as well as quick water supply ability. In addition, the HBG achieved the evaporation rate of 1.37 kg m−2 h−1 with the high photothermal conversion efficiency of 93.7%. This hierarchical design also performed an excellent stability in cycle tests and salt-rejecting experiments as well as achieved remarkable water purification performance by rejecting organics and metal ions. In a word, the HBG is proved to be an efficient and advanced design with excellent stability for solar steam generation. • A novel hierarchical binary gel was designed for efficient solar desalination. • Porous MXene gel as upper structure with high light absorption efficiency. • MMT gel as based materials with low conductivity and quick water supply. • High photothermal conversion efficiency was achieved with 93.7%. [ABSTRACT FROM AUTHOR]