A straightforward α-MoO₃ microwave synthesis for the potential development of applications with a solution-processed layered semiconductor

Molybdenum trioxide (MoO 3 ) has been extensively studied for use in semiconductor devices due to its structural, morphological, and optical properties. In this context, several liquid-phase methods have been reported for synthesizing MoO 3 , with microwave (MW) synthesis offering a fast, simple, and sustainable approach. So far, the described methods have involved processing with strong acids, multiple synthesis steps, the use of low-efficiency solvents, or simply using microwave energy without significant contribution during synthesis. Today, challenges in producing MoO 3 also include developing environmentally friendly processes that reduce reaction time and energy consumption. In this work, MoO 3 was synthesized in a MW reactor from the dispersion of metallic molybdenum powder in a blend of ethanol and hydrogen peroxide, irradiated for 5 minutes at 150°C. This was followed by thermal annealing at 600°C, with a heating rate of 10°C/min. The characterization techniques of X-ray diffraction, FTIR, SEM, UV-Vis spectroscopy, and XPS confirmed the synthesis of orthorhombic α-phase MoO 3 layered flakes (mean thickness ~197 nm, mean diameter ~877 nm), molybdenum-oxygen vibrational modes in the 500–1,000 cm −1 range, an optical band gap of 3.08 eV was determined from Tauc analysis, and the exclusive presence of Mo 6+ oxidation state and bonded oxygen in the XPS spectrum. These results demonstrate a rapid, low-energy liquid-phase approach to functional α-MoO 3 layered flakes, offering a more sustainable synthesis pathway suitable for the potential development of printed and flexible applications through this 2D material.