Superhydrophilic–Superhydrophobic\nMultifunctional\nJanus Foam Fabrication Using a Spatially Shaped Femtosecond Laser\nfor Fog Collection and Detection

Abstract

Fog collection is an effective method\nfor addressing water shortages\nin arid areas. By constructing a Janus structure with asymmetric wettability\non its two sides, flexible and efficient fog capture can be achieved.\nHowever, in situ detection and fog collection on a Janus surface are\nstill challenging tasks. Herein, a novel method for producing a superhydrophilic–superhydrophobic\nJanus fog collector is proposed; the method utilizes a combined process\nin which a spatially shaped femtosecond laser treatment (superhydrophilic)\nis applied to one side of a copper foam and a chemical replacement\nreaction (superhydrophobic) is applied to the other side of the copper\nfoam. Two configurations of the Janus structure were designed to study\ndifferent water transport behaviors. Furthermore, the Au micro–nanoparticle\nprepared adhered to the Janus structure, indicating the effectiveness\nof surface-enhanced Raman spectroscopy detection. The Janus foam shows\nexcellent sensitivity and stability on testing the fog mixed with\nrhodamine 6G. This surface allows for the simultaneous collection\nand detection of fog, which can provide insights into the preparation\nof Janus multifunction structures and how such structures can play\na key role in the subsequent purification and usage of water resources.