3D inverted cone hydrogels derived by MXene-TiOX nanocomposite for sequential regulation of enhanced solar-driven steam generation

Abstract

Solar-driven steam generation technology is an environmentally friendly, cost-effective means of sewage treatment and seawater desalination. A significant challenge in the development of this technology is improving the evaporation performance of evaporation devices. Herein, we report an innovative three-dimensional (3D) solar evaporator constructed with MXene-TiOX nanocomposite as the photothermal layer and polyvinyl alcohol hydrogel as the water-transport medium. An inverted cone-concave structure of 30° on the photothermal layer can absorb more sunlight through diffuse light reflection. The 3D solar evaporator demonstrates a notable evaporation rate of 2.09 kg m⁻² h⁻¹, surpassing the efficacy of alternative evaporative systems. In the seawater desalination experiment, the condensed water had salinity levels that were considerably lower than the established threshold for drinking water. The ion rejection ratios for the four primary ions demonstrate a high level of efficacy, with values approaching 99.91%. In addition, the 3D solar evaporator exhibits robust performance in the context of wastewater treatment. This study provides significant contributions to the understanding of the efficiency of solar evaporators based on structural design principles, offering approaches to mitigate the challenges posed by limited freshwater availability.