Engineering Materials to Enhance Light-to-Heat Conversion for Efficient Solar Water Purification

Water scarcity has become one of the most prevalent problems afflicting people throughout the world and is expected to grow worse in the future due limited resources and increasing demand. This problem calls out for an urgent need to develop inexpensive, stand-alone desalination and water purification technologies that can adopt water resource distribution, water quality conditions, economic status, and developing levels of communities. Solar energy is abundantly available and has become one of the most promising emerging strategies in sustainable water treatment technologies. In this review paper, we highlight the recent progress of solar-driven desalination and water purification technologies for clean water production. We begin by introducing the fundamental concepts of solar radiation, solar thermal conversion, and heat localization. Then, we review the key components of solar steam generation including solar-thermal conversion materials, water pathways, and heat insulators and the strategies to promote efficient solar-to-vapor conversion in terms of chemical regulation, structural engineering, and heat management to maximize solar absorption and to minimize heat loss. Next, we discuss an efficient design of a solar steam generation device using an integrated approach that accounts for the performance of photothermal materials, heat losses, and water supply with respect to the hot evaporation region. Last, existing challenges and future opportunities in both fundamental studies and practical implementations of solar steam generation for water purification are discussed.