Carbon fiber-reinforced carbon foam-based composite phase change materials for efficient photothermal and electrothermal conversion

Inorganic solid-liquid phase change materials (PCMs) offer significant potential for thermal energy storage but are limited by poor shape stability, leakage, and restricted energy conversion modes. We introduce a novel carbon fiber-reinforced, partially graphitized porous carbon framework (PGC-CF) synthesized via a scalable, cost-effective foaming-assisted catalytic graphitization method – a pioneering approach for PCM composites. This 3D interconnected scaffold encapsulates decanoic acid (CA), forming the PCM (CA@PGC-CF-3) composite with 85.7 % PCM loading and a latent heat capacity of 139.5 J/g. The composite exhibits exceptional shape stability and retains 91.7 % of its latent heat after 300 thermal cycles, driven by the synergistic reinforcement of carbon fibers and a partially graphitized matrix. It achieves photothermal conversion efficiencies of 78.9–95.1 % under 75–200 mW cm −2 solar irradiation and electrothermal efficiencies exceeding 80 % at 3 V, enabled by high thermal (0.3216 W/m⋅K) and electrical (∼26 S/cm) conductivities. Unlike costly graphene- or nanotube-based PCMs, this eco-friendly composite leverages abundant sucrose and carbon fibers, offering a scalable platform for solar energy harvesting, smart building thermal management, and electric vehicle energy storage. • 3D porous carbon scaffold was prepared by foaming-assisted catalytic graphitization. • PGC-CF-3 enables 85 % CA loading, achieving a latent heat capacity of 139.5 J/g. • CA@PGC-CF-3 achieves 95.1 % solar-to-thermal conversion efficiency at 200 mW cm -2 . • The composite exhibits >80 % electrothermal conversion efficiency at just 3 V. • CA@PGC-CF-3 maintains structural integrity and thermal stability after 300 cycles.