A Highly Stable <i>Ortho</i>‐Ketoenamine Covalent Organic Framework with Balanced Hydrophilic and Hydrophobic Sites for Atmospheric Water Harvesting

Abstract Atmospheric moisture is a sustainable clean water source that can solve the shortage of fresh water in arid areas. Herein a 2D covalent organic framework (COF‐ok) was reported as a promising porous sorbent for solar‐driven atmospheric water harvesting. COF‐ok with ortho ‐ketoenamine linkage was extremely stable in harsh environment, including in boiling water, strong acids and bases. Because of the balanced hydrophilic and hydrophobic sites in channels, COF‐ok showed a high water uptake of 0.33 g g −1 at a low relative humidity of 34 % featuring a characteristic S‐shaped water sorption isotherm with low regeneration temperature (∼45 °C) and excellent cyclic stability. A laboratory‐scale water harvesting system could collect water of 161 g kg −1 under sunlight.