Advances in full-day and year-round freshwater harvesting: Materials and technologies

Water scarcity affects a significant portion of the global population, with two-thirds experiencing at least 1 month of water scarcity annually. To address this issue, research efforts have focused on developing renewable solar-driven desalination and atmospheric water harvesting (AWH) technologies. However, existing energy-free freshwater harvesting methods are limited by weather conditions and time constraints, hindering their widespread applications. In this critical review, we explore the potential application and research efforts aimed at achieving a full-day (24 h) water supply to enhance their commercial viability. We begin by discussing the material design for solar-driven 3D evaporators, highlighting their potential for water supply during both daytime and nighttime. Subsequently, we delve into promising materials and devices for developing full-day AWH technologies, including fog harvesting, dewing-condensation water harvesting, and adsorption-based water harvesting. Moreover, we examine hybrid water harvesting techniques that combine AWH with solar-driven desalination, highlighting promising material designs to fulfill dual functionality. Finally, we outline the remaining challenges and offer our insights to stimulate further breakthroughs in achieving a year-round full-day water supply. By advancing these technologies and overcoming existing limitations, we can make significant progress in alleviating water scarcity worldwide.