Ligand-free and size-controlled synthesis of oxygen vacancy-rich WO3−x quantum dots for efficient room-temperature formaldehyde gas sensing

Abstract

A facile solvothermal decomposition route was developed for the size-adjustable synthesis of nearly monodispersed, monoclinic-phase WO_3−x QDs with sizes ranging from 1.3–4.5 nm. These QDs, with a high concentration of oxygen vacancies, have strong quantum confinement effects and can strongly absorb near-infrared (NIR) light. A solid–liquid–solid growth mechanism was proposed to explain the formation of the QDs. Experiments demonstrated that the rich oxygen vacancies and ultrathin grain size imparted these WO_3−x QDs with excellent room-temperature formaldehyde sensing properties.