A novel bio-based composite phase change material with excellent photo-thermal conversion capability for solar energy harvesting and energy storage

Organic solid-liquid phase change materials (PCMs) have been widely studied in the field of photo-thermal conversion and thermal energy storage . However, problems such as easy leakage and low efficiency of photo-thermal conversion limit their applications. To solve these problems, this study developed a shape-stable composite phase change material (CPCM) using sponge tissue of discarded corn stem (STCS), polyethylene glycol (PEG), pyrrole (Py), and multi-walled carbon nanotube (MWCNT). PPy and MWCNT enable the CPCM to have excellent photo-thermal conversion capability and thermal conductivity . With 0.2 % MWCNT content, the CPCM achieved a thermal conductivity of 0.4609 W/m·K and a photo-thermal conversion efficiency exceeding 95.3 %. It also demonstrated high enthalpy and relative enthalpy efficiency (152.2 J/g, 96.01 %). Moreover, the CPCM exhibited remarkable shape and thermal stability, with no pyrolysis below 340 °C and nearly unchanged enthalpy after 100 cycles. Meanwhile, this CPCM also showed excellent ability in promoting seawater desalination . This work provides a new idea for recycling of agricultural waste and storage of solar energy as well as desalination of seawater.