Sulfonate-Rich COF-Based CNT Composites for Efficient Solar-Driven Membrane Evaporators and Lithium–Sulfur Battery-Modified Separators

Covalent organic frameworks (COFs) hold great promise in the realm of energy conversion and utilization, but their applications are hampered by their narrow-band spectral response, difficult framework design, and low conductivity at the moment. Here, we designed COF-based carbon nanotubes (CNTs) composites containing sulfonic groups (TB-COF@CNTs), which have good performance in seawater desalination and lithium–sulfur (Li–S) batteries. In seawater desalination, this TB-COF@CNTs membrane evaporator possesses a 97% solar absorption efficiency (at 300–2500 nm), low evaporation enthalpy (2020 kJ kg –1 ), and high rate of evaporation (1.72 kg m –2 h –1 ) and high efficiency (96.5%) (at one sun irradiation). Significantly, the SO 3 – groups can effectively separate anions (for instance, Cl – ) from cations (for instance, Na + ) in the evaporator, preventing the production of solid-salt crystals during the evaporation process. In Li–S batteries, the TB-COF@CNTs-modified separator can also slow down the shuttle of polysulfide and facilitate the migration of lithium ions, demonstrating exceptional electrochemical performance, as its initial specific capacity was 833 mA h g –1 at 0.5 C and subsequently demonstrated 633 mA h g –1 after 200 cycles. Our study presents a feasible approach to rationally design functional COFs-based CNT composites, thereby enhancing their potential applications in integrated energy systems.