All-in-one self-cleaning lignin-derived spherical solar evaporator for continuous desalination and synergic water...

Solar-driven photocatalytic degradation of pollutants and promotion of interfacial evaporation have emerged as a promising approach to address environmental pollution and freshwater scarcity. However, the construction of integrated photothermal/photocatalytic materials and the underlying synergistic mechanisms are still poorly understood. Herein, a spherical evaporator (LCNB) was developed by rationally designing lignin-derived carbon-doped g-C₃N₄ (LCN) as a photothermal/photocatalytic material incorporated into sodium alginate and polyvinyl alcohol as a hydrophilic regulator, followed by cross-linking with CaCl₂. LCNB can self-assemble into a dynamic plane system for thermal localization and the gravitational changes of LCNB lead to rotation to dissolve precipitated salt and realize continuous desalination. Theoretical calculations revealed that carbon-doping reduces the band gap and thus improve the photothermal/photocatalytic efficiency. LCNB achieved a maximum evaporation rate of 1.64 kg m^-2 h^-1 under one solar irradiance while demonstrating no-salt accumulation for 12 h of continuous operation in 20wt % NaCl solution and an excellent photodegradation efficiency of 85.64 % for tetracycline hydrochloride. Overall, this study establishes a promising framework for multifunctional solar evaporators by incorporating the LCN as the photothermal/photocatalytic material, effectively tackling desalination and pollutant degradation challenges while highlighting the potential of renewable resources in advanced material development.