Engineering oxygen vacancy defects on a CeO2-SnO2 micro-nano heterostructure for rapid triethylamine detection and fish freshness monitoring

Oxygen vacancy defects on the surface of metal oxides can not only increase carrier density and facilitate electron transfer, but also increase more active sites, thereby significantly boosting the overall performance of sensors. In this study, a 3D bundle-like porous CeO₂-SnO₂ heterostructure with abundant oxygen vacancy defects composed of radially cross-bundled mesoporous nanorods is successfully prepared. The synergistic effects of composition regulation, Ce⁴⁺/Ce³⁺ valence engineering, and increased oxygen vacancy defects in the micro-nano structure enhance electron transfer at the interface, creating more active sites for triethylamine (TEA) capture. Consequently, the micro-nano structure shows an outstanding response value of 151.12 towards 100 ppm TEA at 157 °C, about six times higher than SnO₂, with excellent selectivity, fast response/recovery times (9 s/123 s), superior anti-interference ability, and long-term stability. Also, the sensor can achieve a response value of 11.24 for TEA detection in gases from five-day-stored crucian carp at room temperature, showing potential for freshness monitoring. This work presents an effective strategy to develop TEA sensors for practical applications by using oxygen valence engineering and tailoring multi-scale pore structures in MOF-derived heterostructures.