Defect engineering on SnO2 nanomaterials for enhanced gas sensing performances

Although defect engineering opens up new opportunities in the field of gas sensors, the introduction of defects to enhance the gas sensing properties of metal oxide semiconductors (MOSs) has long been neglected. In this review, defect engineering strategies have been systematically introduced, with a focus on employing them for improved gas sensing performances. To keep the subject focused, we take SnO2 nanomaterials as an example. Various synthesis methods for defective SnO2, including ion/electron/ray/laser-beam irradiation, plasma treatment, heating protocol, chemical reduction, tailoring specially exposed crystal facets and atoms doping, are emphasized. Different roles of defects on the gas sensing process of SnO2 are discussed. Finally, critical issues and future directions of defect engineering are presented. This paper provides a platform for better understanding the relationships between synthesis, defect types and gas sensing performances of MOSs. It is also expected to unpack an important research direction for controlled synthesis of defective nanomaterials with other applications, including advanced energy conversion and storage.