Low-tortuosity water microchannels boosting energy utilization for high water flux solar distillation.

Solar distillation through photo-thermal evaporators has approached solar light energy (E1) limit under no solar concentration, but still suffers from modest vapor and clean water production. Herein, a nature-inspired low-tortuosity 3D evaporator is demonstrated to significantly improve water production. The solar evaporator, prepared from polypyrrole-modified maize straw (PMS), had upright vascular structures enabling high water lifting and horizontal micro-gaps facilitating broad water distribution to the out-surface. Consequently, this novel PMS evaporator dramatically enhanced the utilization of the heat energy stored in the environment (E2) for promoting evaporation. The maximum vapor generation rate of a single PMS respectively increases 2.5 times and 6 times compared with the conventional 3D evaporators and the planar evaporators of identical occupied area. Consequently, a scaled-up PMS array achieved a state-of-the-art vapor generation rate of 3.0 L m-2 h-1 (LMH) under simulated condition and a record-high clean water production of 2.2 LMH for actual seawater desalination under natural conditions (one-sun intensity). This breakthrough reveals great potentials for cost-effective freshwater production as well as the rational design of high-performance photothermal evaporators for solar distillation.