Oxygen vacancy engineered tin dioxide/tungsten disulfide heterostructure construction for effective NO sensing

Abstract

High-performance NO gas sensors operating at low temperature are urgently desirable for both civilian and industrial purposes. However, it remains a great challenge to prepare tin dioxide (SnO₂)-based hybrids in a simple and effective way and realize low operating temperature and high sensitivity/selectivity simultaneously. Here, we demonstrate the successful construction of a SnO₂/tungsten disulfide (WS₂) heterostructure using a simple hydrothermal method. By taking advantage of SnO₂ nanocrystals dispersing uniformly on WS₂ nanosheets and the increased oxygen vacancies as well as the existence of Sn²⁺, the SnO₂/WS₂ hybrid heterostructure shows a significant improvement in response and a much better selectivity to NO compared with the SnO₂ microspheres. More importantly, the response (R_g/R_a) of the SnO₂/WS₂ hybrid to 5 ppm NO is 6.24 at 75 °C, which is 6.10- and 4.21-fold higher than that of the SnO₂ microspheres and WS₂ nanosheets, respectively. Thus, the hybrid heterostructure displays good performance with better selectivity, shorter response/recovery time and good repeatability, indicating its potential application in monitoring NO gas exhaled by humans.