Synthesis and properties of biomass derived carbon/PEG composite as photothermal conversion effective phase change material for functional concrete

Mixing phase change material (PCM) into concrete is a practical strategy for functionalizing concrete as an energy-storage unit. This study aims to invent an efficient photo-thermal conversion type PCM for the manufacturing energy storage functional concrete, which meet the needs of hydration heat storage and thermal storage in service. To solve the liquid leakage problem of PCM, a novel bamboo-based hydrothermal carbon sphere (HCS) with unique mesoporous structure was prepared to pack polyethylene glycol (PEG) to make shape stable PCM. The photo-thermal material nano-Ag was successfully introduced into the composite PCM through a high-voltage electrostatic field. To understand the stability and performance of the PCM for concrete use, the structural composition and thermal storage efficiency of Ag@HCS-CNTs/PEG in simulated concrete pore solution (a highly alkaline solution containing potassium, sodium, and calcium cations) were systematically studied via multiple characterization methods. After being soaked in concrete pore solution for 7 days, the PCM shows outstanding thermal storage density (147 J/g), photo-thermal conversion efficiency (110.6%), and resistance to Na+, Mg2+, Cl− and SO42−. In addition, the biomass subtracted PCM preparation has low energy consumption and low carbon emission features. These open a window of realistic PCM application in the structural concrete, insulation porous walls and energy storage buildings.