Upgrading CO2-captured porous carbon into flexible phase change films for efficient photohermal energy conversion

Integrating carbon capture with solar energy storage offers a promising pathway toward carbon neutrality, yet the synergistic utilization of carbonaceous materials from capture processes remains underexplored. Herein, we fabricate a flexible phase change film (PCF) using porous carbon derived from the reciprocal carbon–carbonate co-calcination (RCCC) of bamboo biochar and limestone. During RCCC, 93.2% of CO 2 released from limestone is converted to CO. The optimized PCF composed of BC, thermoplastic polyurethane, and microencapsulated eicosane achieves a phase change enthalpy of 123.87 J g −1 , excellent leakage-proof and mechanical stability. The photothermal conversion efficiency can reach 85.5%. This work demonstrates the first integration of RCCC-based carbon capture with flexible photothermal energy storage, offering a viable route for upgrading captured carbon into functional solar-thermal materials.