The nexus of solar absorption and morphology designs based on 2D photothermal materials: From rational design to advanced application of water purification

Water scarcity and energy crisis have forced people to urgently develop advanced water purification techniques with a sustainable energy source. Solar thermal conversion technology with a green, low-cost, and low carbon footprint attracts attention in the application of water treatment. Photothermal materials, which convert sunlight into heat, are key to solar energy utilization. This paper reviewed the progress of the application and design strategy of two dimensional (2D) photothermal materials, such as graphene, MXene, and transition metal dichalcogenides, in water treatment and related fields. The evaluation criterions for light absorption and photothermal conversion efficiency of materials were further described. Then, building different light-capture structures (microscopic pore structure, hierarchical structure, and bionic structure) by morphology engineering that solve the limitation of tightly stacked 2D photothermal materials with light reflection was the main concern. Finally, the challenges and prospects toward 2D photothermal materials in the application were discussed. This review aims to improve the understanding of the mechanism of thermal performance improvement and the structure-activity relationship of materials by summarizing the effect of 2D photothermal materials morphology regulation on enhanced light absorption.