Direct laser writing carbonization of polyimide films enabled multilayer structures for the use in interfacial solar-driven water evaporation

Abstract

Due to their highly efficient and broad-band optical absorption characteristics, different types of carbon materials, e.g., carbon black, carbon fibers, carbon foam, carbon nanotubes, graphene, etc., have been explored for the use as light absorbing materials in the emerging technology of interfacial solar-driven water evaporation. Nevertheless, the current approach for fabricating/integrating/assembling a highly efficient water evaporation system typically involves a tedious multi-step process, in which the light-absorbing materials are separately prepared by a sophisticated wet-chemistry approach and then integrated with the underlying insulation layer. Herein, we manifest a simple approach that relies on a direct laser writing carbonization (DLWc) method in conjunction with HNO₃ oxidation treatment for fabricating multi-layer structured interfacial solar-driven water evaporation systems. With this approach, two different types of water evaporation systems are designed, fabricated, characterized and evaluated, which include the perforated hydrophobic carbon/polyimide/hydrophilic carbon tri-layer TLF system and an inverted V-shaped hydrophilic carbon/polyimide bi-layer BLV system. Depending upon the design schemes, the DLWc enabled interfacial solar-driven water evaporation systems achieve high water evaporation rate in the range of 1.11–1.73 kg m⁻² h⁻¹ with excellent long-term stability and mechanical robustness. The efficient, scalable and low-cost fabrication process and the excellent water evaporation performance of the DLWc enabled water evaporation systems make them highly promising in the niche application of compact, stand-alone and portable water purification use.