Bioinspired Unidirectional 3D Scaffold for Synergistic Enhanced Solar Evaporation and Efficient VOCs Degradation.

3D design has effectively enhanced photothermal materials water evaporation performance via utilizing side surfaces. However, for photothermal/photocatalytic composite evaporators which can effectively degrade volatile organic compounds (VOCs) to prevent their contamination in condensate, introducing 3D design should promote VOCs escaping from the evaporator sides surface, reducing efficiency of VOCs photocatalytic degradation. Herein, a bioinspired unidirectional silk fibroin (SF)-Ag2S/Ag3PO4 3D evaporator is reported to achieve synergy between enhancing water evaporation and maintaining VOCs photocatalytic degradation efficiency. The unidirectional channels are modified with Ag2S/Ag3PO4 composite as both photothermal and photocatalytic agents. By promoting directional water transfer, the bioinspired unidirectional scaffold achieves an evaporation rate of 2.86 kg m-2 h-1 under 1 sun with the assistance of side-surface evaporation. Furthermore, the unidirectional channels effectively restrict the horizontal migration and the escape of VOCs from side surface, directing their transport toward the top surface, where the VOCs can be photocatalytically degraded by Ag2S/Ag3PO4 composite. Accordingly, bioinspired SF-Ag2S/Ag3PO4 scaffold maintains 91.9% VOCs removal performance under 1 sun in 10 mg L-1 phenol-contaminated water. Moreover, compared with the evaporator without directional VOCs transportation, bioinspired scaffold shows 96% and 41% increase in VOCs removal and water evaporation, respectively, under 2 suns in 100 mg L-1 phenol solution.