Dimension dependency of tungsten oxide for efficient gas sensing

Abstract

Air pollution is a serious concern worldwide as it affects living beings and the environment due to the release of hazardous gases and particulate matter. The major cause of pollution is toxic gases which are released by industries, automobiles, waste and stubble burning, etc. In order to detect and monitor toxic gases like CO, NO_x, H₂S, SO₂, NH₃etc., metal oxide-based gas sensors are developed owing to their exotic properties such as high sensitivity, rapid response, and recyclability as well as long stability. Among these metal oxides, tungsten oxide (WO₃) is a transition metal oxide having enormous potential in gas-sensing applications. It is perceived that the morphology of tungsten oxide plays a significant role in the effective detection of these hazardous gases. The low dimension (0D, 1D, 2D) and hierarchical structures of WO₃ exhibit enhanced sensitivity and are utilized for efficient sensing of various gases. In this review, we have comprehensively discussed the effect of the morphology of tungsten oxide nanostructures and their application in detection of gases such as H₂, NH₃, H₂S, CO, O₃, VOCs etc. Further, the sensing mechanism along with the impact of surface functionalization and doping has been discussed. The challenges in the field and future prospects have also been discussed.