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 (Ti3C2) 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 Ti3C2 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.