Biomimetic hydrogel with directional heat regulation for efficient solar desalination

Solar-driven interfacial evaporation desalination has emerged as a promising strategy for alleviating the water scarcity crisis. However, the design of evaporators with excellent heat management and minimal heat loss to achieve high-efficiency clean water production remains a crucial challenge. Herein, inspired by the transpiration of mushrooms in nature, we demonstrated a bionic-structured hydrogel evaporator, fabricated with biomass lotus root starch (LR), polyvinyl alcohol (PVA), and ink-modified carbon quantum dots and TiO₂ (i-CQDs-TiO₂). The evaporated water can be instantly replenished during evaporation through the internal water circulation of the “stipe”, and the special structural design reduces the transfer of heat to the water. Therefore, the evaporator demonstrates excellent performance, with a pure water evaporation rate of up to 3.78 kg·m⁻²·h⁻¹ and an efficiency of 98% (1 kW·m⁻²). More importantly, the evaporator has excellent salt resistance with an average evaporation rate of 3.49 kg·m⁻²·h⁻¹ in 1–25 wt% brine. In addition, without salt scaling on the evaporation surface in 10 wt% brine for continuous 5 h of illumination. Furthermore, due to the coordinated photocatalysis of i-CQDs and TiO₂, the catalytic degradation rates of TB and CR were up to 91.8% and 88.9%, respectively. With an efficient and stable desalination capacity, this solar evaporator with a bionic design offers a new pathway for sustainable solar desalination.