Low-Cost Near-Infrared Photothermal Crystalline Coordination Polymers

Crystalline coordination polymers (CCPs) have emerged as promising platforms for photothermal conversion due to their structural tunability. However, the development of high-performance CCPs is often limited by the high cost of photoactive ligands. In this study, we report a low-cost, scalable approach to synthesize three CCPs─Cu-CCP, Co-CCP, and Zn-CCP─via a solvothermal method using the inexpensive industrial precursor tetrafluoroterephthalonitrile, which is converted in situ into a tetraoxolene ligand. Cu-CCP displays broad absorption extending into the second near-infrared (NIR-II, 800-1500 nm) region and shows a rapid photothermal response under 808 and 1064 nm laser irradiation, with conversion efficiencies of 49.3 and 67.4%, respectively. Co-CCP also exhibits strong NIR absorption across 800-1500 nm with excellent NIR-II photothermal performance. Owing to the full-spectrum absorption characteristics, Cu-CCP was further applied in solar-driven water evaporation experiments, achieving a high evaporation rate of 1.173 kg·m^-2·h^-1 and an efficiency of 79.5% under 1 sun irradiation. This work highlights a cost-effective route for the construction of high-performance NIR photothermal materials from industrially accessible precursors.