Form-stable phase change composites with multistage pores based on black phosphorus nanosheets/PVA aerogel for efficient solar photothermal conversion

The development of the form-stable Phase Change Materials (FPCMs) with excellent solar-thermal conversion performance is crucial for sustainable solar energy utilization. However, the leakage of organic phase change materials limits its practical application. Herein, we reported a novel multistage porous aerogel fabricated from black phosphorus (BP) nanosheets, polyvinyl alcohol (PVA) and carbonized kapok (CK) fibers by a solution blending method. The aerogel was directly dipped in molten hexadecanol as the phase change material. The results showed that the HD/PVA-BP30 had a phase change temperature of 55 °C, latent heat of phase change of 164.3 kJ/kg. After 100 melting/freezing cycle, the phase change composite leaks only 0.38 %. The mechanical properties of PVA-BP30 exhibited a compressive strength of 1.04 MPa at 80 % strain, and the mechanical strength of the aerogel increased with increasing BP content. The addition of BP also enhanced the photothermal conversion (73.6 %) under 1 sun illumination. The prepared HD/PVA-BP30 have the characteristics of the suitable phase change temperature, excellent melting/freezing cycle reliability, strong mechanical properties, and anti-leakage properties. Therefore, the reported FPCMs are anticipated to have great potential for solar water heater utilization in bath water.