Facile Preparation of Oxygen-Vacancy-Engineered MoO(x) Nanostructures for Photoreversible Switching Systems

Photochromic materials have attracted increasing attention. Here, we report a novel photo-reversible color switching system based on oxygen-vacancy-engineered MoO(x) nanostructures with water/N-methyl-2-pyrrolidone (NMP) as solvents. In this work, the system rapidly changed from colorless to blue under UV irradiation (360–400 nm) and slowly recovered its colorless state under visible light irradiation. The obtained oxygen vacancy-engineered MoO(x) nanostructures exhibited good repeatability, chemical stability, and cycling stability. Upon UV light irradiation, H(+) was intercalated into layered MoO(x) nanostructures and the Mo(6+) concentration in the H(x)MoO(x) decreased, while the Mo(5+) concentration increased and increased oxygen vacancies changed the color to blue. Then, it recovered its original color slowly without UV light irradiation. What is more, the system was highly sensitive to UV light even on cloudy days. Compared with other reported photochromic materials, the system in this study has the advantage of facile preparation and provides new insights for the development of photochromic materials without dyes.