Microwave Electrification as a Process-Intensification Strategy for Calcination-Free, Scalable, and Sustainable Synthesis of Anatase-TiO ₂ /α-Fe ₂ O ₃ Photocatalysts

While anatase-TiO2/α-Fe2O3 (ATAF) composites are promising visible-light photocatalysts, their conventional synthesis is hindered by prolonged processing and high-temperature calcination, which limits scalability and increases energy consumption. This work demonstrates a rapid, single-step microwave-hydrothermal strategy to fabricate phase-pure ATAF composites within 10 min, entirely without calcination. This method facilitates the heterogeneous nucleation of anatase-TiO2 onto α-Fe2O3 particles, creating an intimate interface. By optimizing the α-Fe2O3 content with uniform TiO2 decoration on it, an ATAF composite exhibiting superior charge separation, as evidenced by significant photoluminescence quenching, is prepared. This optimal interface engineering results in a remarkable 99.9% photocatalytic degradation of methylene blue under visible light, significantly outperforming the individual constituents. This energy-efficient approach potentially reduces synthesis energy consumption by one to 2 orders of magnitude compared to conventional calcination routes, while the use of aqueous solvents and a closed system aligns with the principles of clean production. The combined advantages of rapid processing, energy efficiency, and scalability position this method as a viable pathway for the industrial-scale production of high-performance photocatalytic composites. The microwave-assisted hydrothermal synthesis demonstrates process electrification by transitioning from conventional furnace-based thermal treatment to direct microwave heating, resulting in reduced energy consumption and associated CO2 emissions.