Photothermal Conversion and Thermal Management of Magnetic Plasmonic Fe₃O₄@Au Nanofluids

As a sustainable and widely available source of clean energy, solar energy has great potential for solving the aforementioned issues. Nanofluids (NFs)-based direct absorption solar collectors can convert solar energy into thermal energy, which has been widely applied in energy-thermal conversion and wastewater purification. However, the low photothermal modulation efficiency of NFs limits the industrialization of solar collectors. Herein, the Fe3O4@Au composite structure is constructed using coprecipitation method. The effect of different parameters, such as Au loading, concentration of NFs, external magnetic field, and flow rate on the optical and photothermal properties of the Fe3O4@Au NFs and Fe3O4 NFs are systematically studied. The results reveal that the solar energy-weighted absorption fraction of Fe3O4@Au reaches 97.54% with a low concentration of 0.0667 vol%. Besides, the heat distribution can be controlled using an external magnetic field owing to the magnetic properties of Fe3O4 in water evaporation devices. The evaporation rate of Fe3O4 evaporator and Fe3O4@Au evaporator is 1.8 and 2.3 kg m(-2) h(-1), respectively, confirming their excellent and stable solar energy harvesting ability. The prepared Fe3O4@Au NFs are a promising approach in efficient photothermal conversion and thermal management in solar energy harvesting.