Thermal energy is essential for improving energy efficiency and sustainability, particularly in solar energy harvesting and the utilization of waste resources. By incorporating novel energy materials for storage, such as phase change materials (PCMs), and enhancing heat transfer with nanofluids, we can effectively capture and store this energy for future use. My PhD research centers on synthesizing nanoparticles from double metal oxides, including CoFe₂O₄, NiFe₂O₄, SrTiO₃, and BaTiO₃, using microwave-assisted solvothermal reactions. This approach offers significant benefits, such as accelerated synthesis, simplified scalability, and enhanced reaction effectiveness. Additionally, by formulating innovative nanofluids with these nanoparticles, we aim to improve heat transfer efficiency and tackle critical challenges in thermal energy management.