Gas Foaming Guided Fabrication of 3D Porous Plasmonic Nanoplatform with Broadband Absorption, Tunable Shape, Excellent Stability, and High Photothermal Efficiency for Solar Water Purification

Abstract Solar steam generation is an efficient way for water purification. However, it is still challenging to establish a steam generation system possessing high evaporation efficiency under natural sunlight condition with good durability. Herein a novel, free‐floating nanoplatform is constructed by a gas foaming strategy, embedding plasmonic Cu 7 S 4 ‐MoS 2 ‐Au nanoparticles (CMA NPs) in porous polydimethylsiloxane (PDMS) matrix. The gas diffusion process creates 3D porous PDMS matrix with low thermal conductivity and open channels, which allows for efficient energy confinement and fast water supply in an integral matrix, beneficial to mechanical strength of the system. By taking advantage of broadband absorption and high photothermal efficiency of CMA NPs and structural design of the matrix, the nanoplatform achieves a high evaporation rate (3.824 kg m −2 h −1 ) and photothermal conversion efficiency (96.6%) under one‐sun illumination (1 kW m −2 ). Moreover, such performance maintains stable even under harsh conditions in the presence of strong acid, strong base, strong oxidants, and high salinity, suggesting a broad prospect in seawater desalination, sewage treatment, sterilization and so on.