When Coordination Polymers Meet Wood: From Molecular Design toward Sustainable Solar Desalination

Solar-driven interfacial evaporation harnessing solar energy on a water surface provides a sustainable and economic means to efficiently capture freshwater from nontraditional water sources. Endowed with a hierarchical porous structure and mechanical stability, wood-based evaporators represent a renewable alternative to petroleum-based materials. Nonetheless, incidental inferiorities of a low evaporation rate and weak interfacial strength are challenging to overcome. Herein, we propose the usage of chemically stable coordination polymers (Ni-dithiooxamidato, Ni-DTA) as hydrophilic photothermal nanomaterials for the molecular design of robust wood-based evaporators with improved performance. In situ synthesis of Ni-DTA onto the channel wall of balsawood provides sufficient photothermal domains that localize the converted energy for facilitated interfacial evaporation. A rational control of methanol/dimethylformamide ratios enables the coexistence of 1D-nanofibers and 0D-nanoparticles, endowing Balsa-NiDTA with a high evaporation rate of 2.75 kg m-2 h-1 and an energy efficiency of 82% under one-sun illumination. Experimental and simulation results reveal that Ni-DTA polymers with strong hydration ability decrease the equivalent evaporation enthalpy induced by decreased H-bonding density of water molecules near the evaporation interface. The Balsa-NiDTA evaporator showed a high chemical stability, mainly due to the robust Ni-S/Ni-N bonds and the superior cellulose affinity of Ni-DTA. Furthermore, the Balsa-NiDTA evaporator shows an excellent antibacterial activity and low oil-fouling propensity. This work presents a facile and mild strategy to design chemically stable wood-based evaporators, contributing to highly efficient and sustainable solar desalination under harsh conditions.