A PDMS@Fe₃O₄ nanocomposite material-based solar interfacial evaporator prepared using a picosecond laser

Solar interfacial evaporation, as an efficient, cost-effective, and green way of desalination, provides a solution to the problem of freshwater resource shortage. However, the materials commonly used for evaporators have high surface reflectivity and poor water production performance. The practical requirements cannot be satisfied. Here, nanocomposites with different mass fraction ratios of polydimethylsiloxane (PDMS) and ferrous ferric oxide (Fe₃O₄) were prepared, and their surfaces were textured using picosecond laser processing technology. Experimental results show that for the laser treated PDMS@Fe₃O₄ (LT-PDMS@Fe₃O₄) surface, its reflectivity within a wide spectral range can be less than 1%. When the mass fraction ratio of PDMS to Fe₃O₄ is 1.5 : 1, the evaporation efficiency of the sample is the highest. Moreover, when steam escape holes are processed on the surface of this nanocomposite material, its evaporation rate under simulated light illumination (2 kW m^-2) can reach 9.55 kg m^-2 h^-1. An evaporation rate of 1.94 kg m^-2 h^-1 can be achieved by this interfacial evaporator under real light illumination (0.97 kW m^-2). Five detected metal ions in the collected freshwater are all below the standard limits set by the WHO. The achievements of this study are expected to provide strong technical support for efficient and sustainable steam generation.