Multifunctional Nanoporous Flash Graphene Coating for Solar Evaporator with Salt Resistance, Microplastic Rejection, and All‐Day Purification

Multifunctional solar‐driven evaporators are emerging as key technologies for addressing global water scarcity through efficient seawater desalination and wastewater treatment. In this study, we report a novel flash graphene (FG) material synthesized through the flash joule heating (FJH) process and its application in a nanoporous multifunctional coating for high‐performance solar evaporators. The FG‐coated evaporator exhibits strong solar absorption (93.8%) and excellent gas permeability (93% of the bare melamine foam), enabling enhanced photothermal conversion and efficient vapor release. Under 1 sun irradiation, the system achieves a high evaporation rate of 3.08 kg·m ⁻² ·h ⁻¹ , with a solar‐to‐vapor efficiency of 95.3%. The hydrophobic nature of the FG layer effectively prevents salt crystallization, ensuring long‐term operational stability. Additionally, the conductive FG network facilitates electrothermal heating, achieving 2.79 kg·m ⁻² ·h ⁻¹ under a voltage of 7V. When combined with solar illumination (1 sun + 7 V), the evaporation rate increases to 4.58 kg·m ⁻² ·h ⁻¹ , demonstrating a strong synergistic effect and enabling all‐day seawater desalination. Furthermore, we demonstrate the ability to purify wastewater by removing dyes and microplastics, highlighting its potential in various environmental applications. This approach provides an efficient, recyclable solution for advancing solar desalination technologies.