Solar evaporation of liquid marbles with Fe₃O₄/CNT hybrid nanostructures

Through the rational design of nanomaterial composites, broadband light harvesting and good thermal insulation can be achieved simultaneously to improve the efficiency of water evaporation.

Solar evaporation experiments were carried out on liquid marbles (LMs) coated with Fe₃O₄ nanoparticles, carbon nanotubes (CNTs) and hybrid nanomaterials (Fe₃O₄/CNTs) with different mass ratios of 2:1, 1:1 and 1:2.

The results showed that the mixture of Fe₃O₄/CNTs enhances the light harvesting ability and solar interfacial evaporation performance. Fe₃O₄/CNT-LM at the mass ratio of 2:1 case provides the highest evaporation rate of 11.03 μg/s, which is about 1.22 and 1.34 times higher than that of Fe₃O₄ and CNT, respectively. This high performance is mainly due to the synergistic effect between Fe₃O₄ nanoparticles and CNTs, as the hybrid nanostructure significantly improves the both photothermal conversion and heat localization capability. Numerical simulation further supports that the composite can concentrate the electromagnetic field and heat at the phase-change interface. This leads to a rapid evaporation of the boundary region. This study provides a novel approach to a three-dimensional interface by assembling nanomaterials on the drop surface to enhance evaporation, which may have far-reaching implications for seawater desalination.