Facile synthesis and study of the photochromic properties of deep eutectic solvent-templated cuboctahedral-WO3/MoO3 nanocomposites

Abstract This paper reports the synthesis of tungsten oxide-molybdenum oxide composite using a simple, cost-effective and environmentally friendly method using deep eutectic solvent, DES (ethaline) at low temperatures. The XRD revealed that the composites were made up of agglomerated particles in the amorphous state at crystal sizes ranging from ∼56.0 nm to ∼68.0 nm, depending on the hydrothermal temperatures, while it was found that the crystal sizes reduced with increasing temperature. The SEM and TEM showed that the as-prepared composite consists of aggregated, cuboctahedra-like crystal particles with nanopores at 60 °C, which form the building block. Furthermore, the UV–Vis measurement indicated an intense response to UV radiation in the range of 200–460 nm, with a maximum absorption at ∼460 nm and a threshold value at ∼540 nm and a wide band gap energy of 3.87–3.95 eV. In addition, the as-prepared composite exhibited color change from cream-yellow to blue within 5 s irradiation exposure and reversibility in 90 min, with remarkable cyclability.