Co/N co‐doped flower‐like carbon‐based phase change materials toward solar energy harvesting

Abstract The photothermal conversion capacity of pristine organic phase change materials (PCMs) is inherently insufficient in solar energy utilization. To upgrade their photothermal conversion capacity, we developed bimetallic zeolitic imidazolate framework (ZIF) derived Co/N co‐doped flower‐like carbon (Co/N‐FLC)‐based composite PCMs toward solar energy harvesting. 3D interconnected carbon framework with low interfacial thermal resistance, abundant carbon defects and high content of nitrogen doping, excellent localized surface plasmon resonance (LSPR) effect of Co nanoparticles, and light absorber Co 3 ZnC in Co/N‐FLC synergistically upgrade the photothermal capacity of (polyethylene glycol) PEG@Co/N‐FLC composite PCMs with an ultrahigh photothermal conversion efficiency of 94.8% under 0.16 W/cm 2 . Uniformly anchored Co and Co 3 ZnC nanoparticles in carbon framework guarantee excellent photon capture ability. Bridging carbon nanotubes (CNTs) in 2D carbon nanosheets further accelerate the rapid transport of phonons by constructing cross‐connected heat transfer paths. Additionally, PEG@Co/N‐FLC exhibits a thermal energy storage density of 100.69 J/g and excellent thermal stability and durable reliability. Therefore, PEG@Co/N‐FLC composite PCMs are promising candidates to accelerate the efficient utilization of solar energy.