Preparation and characterization of novel CuS / SiO 2 @n‐octadecane phase‐change nanocapsules enhanced photothermal conversion for solar energy utilization

The design of CuS/SiO2@n-octadecane nanocapsules with high sensitivity to light and heat is being conducive to photothermal conversion and efficient utilization of solar energy. In this work, CuS was deposited on the surface of the SiO2 shell by the chemical bath deposition method. Through the characterization of microstructure and chemical composition, the granular CuS crystal was uniformly coated on the SiO2 shell. The synthesized nanocapsules are spherical and have a perfect core-shell structure. The quantity, distribution, and size of CuS deposited on the shell can be adjusted by regulating the synthesis parameters. The prepared CuS/SiO2@n-octadecane nanocapsules have a melting temperature of 26.85°C and melting enthalpy of 65.0 J/g at the optimum preparation condition (10 mmol/L cetyltrimethylammonium bromide, 70°C, 0.02 mol/L Cu2+) and have excellent durability. The light absorption performance of CuS/SiO2 nanocapsules in the Vis-NIR was significantly enhanced, photothermal conversion efficiency reached 52.7%. In addition, the CuS/SiO2 nanocapsules also showed good photocatalytic performance, and the degradation degree of methyl orange reached 71% within 3 hours. These results show that the designed photo-driven nanocapsules have excellent performance and great potential in solar energy utilization and intelligent fabric. Highlights We have creatively synthesized PCM nanocapsules with CuS/SiO2 shells. The melting enthalpy and melting temperature are 65.0 J/g and 26.85°C, respectively. The activity of the SiO2 shell was increased by amino coupling agent modification. CuS has increased 4-5 times of photothermal conversion efficiency in Vis-NIR.