Recent developments of hydrogel based solar water purification technology

Water scarcity is a severe problem all over the world; however, most current large-scale water purification technologies are energy-intensive and require high capital and maintenance costs. Recently, hydrogel-based solar water purification technologies have attracted increasing attention due to their advantages, including easy preparation, less energy intensive, and highly efficient solar absorption and utilization. This review summarizes recent advances in the development of novel hydrogel materials from two perspectives: improving solar-thermal conversion efficiency, and facilitating water transport. The main strategies to achieve higher conversion efficiency include choosing good solar absorbers, constructing a surface to reduce light reflection and reducing heat loss. Adjusting wettability, tuning the physio-chemical properties of internal channels, and increasing the intermediate water content to lower the water vaporization enthalpy are the three main approaches for rapid water transport. This review also provides new insights into future directions and remaining challenges in this field.