| Materials | Advantage | Disadvantage | ref |
|---|---|---|---|
| Pure SMOs | minimal response/recovery time | minimal sensitivity, high operating temperature, low detection limit | 137~140 |
| Doped SMOs | high sensitivity, lower detection limit, short response/recovery time | slightly lower operating temperature | 78,80 |
| SMOs-SMOs composites | enhanced selectivity, short response/recovery time, improved operating temperature | slightly improved response, slightly improved detection limit | 95 |
| Conjugated polymer-conjugated polymer composites orconjugated polymer/non-conjugated polymer-SMOs composites | low operating temperature, high selectivity, minimal detection limit, minimal response/recovery time | minimal response | 115,141 |
| Graphene-SMOs composites | lower operating temperature, minimal response/recovery time, minimal detection limit | minimal response | 142~144 |
Fig.4 (a) Schematic illustration of synthetic process of PdO@ZnO-SnO2 NTs; (b) SEM image of as-spun Pd@ZIF-8/PVP/Sn composite NFs;(c) TEM image of as-spun Pd@ZIF-8/PVP/Sn composite NFs;(d) SEM image of PdO@ZnO-SnO2 NTs;(e) Dynamic acetone response transition in the concentration range of 0.0001‰~0.005‰ at 400 ℃; (f) selective sensing characteristics of PdO@ZnO-SnO2 NTs toward 0.001‰ of various analytes at 400 ℃ [