Iron-catalyzed laser-induced graphene on cellulose paper for solar-driven interfacial evaporation

Solar-driven interfacial evaporation has emerged as a promising strategy to produce freshwater via seawater desalination. While cellulose-based photothermal materials have garnered significant attention in solar steam generation, conventional surface modification techniques (e.g., coating and carbonization) often suffer from cumbersome preparation and limited design flexibility. This study pioneers a non-destructive laser-processing strategy to simultaneously induce spatially controlled graphene domains and iron oxide nanostructures on chemically modified cellulose matrices. Through synergistic integration of broadband light absorption (∼93.28% solar-weighted absorptance) with hierarchical water channels, the two-dimensional evaporator achieves exceptional evaporation performance (1.62 kg m^-2 h^-1, 99.0% efficiency) under 1 sun irradiation. Remarkably, the evaporation performance increases to 1.82 kg m^-2 h^-1 when configured into a three-dimensional architecture via simple single folding. Detailed characterizations reveal that laser-induced carbothermal reduction generates iron oxide-graphene composites as light absorbers, while preserving cellulose's inherent hydrophilicity for rapid capillary pumping. Notably, the engineered architecture demonstrates enhanced mechanical robustness (234% improvement in tensile strength) and programmable foldability, expanding applicability across diverse desalination scenarios. This laser-direct-writing paradigm establishes a sustainable pathway for developing next-generation cellulose-based solar evaporators.